Materials Today Communications (23524928)44
During the last decade, researchers have developed synthetic substances that mimic the properties of enzymes due to the limitations of natural enzymes. This has led to the creation of nanozymes, nanomaterials with enzyme-like catalytic properties. Herein, iron oxide nanozymes (Fe3O4) with peroxidase-like activity (POD) were synthesized via a single-step solvothermal process. Subsequently, these nanozymes were surface-functionalized with nanocellulose, a biocompatible and biodegradable biopolymer, to examine its influence on POD-like activity. A significant 42.7 % increase in specific POD-like activity was observed for Fe3O4 nanozymes functionalized with nanocellulose (Fe3O4@NC), accompanied by a six-fold enhancement in maximum velocity (vmax) for the 3,3′,5,5′-tetramethylbenzidine (TMB) substrate. The Fe3O4@NC nanozymes were capable of utilizing intracellular hydrogen peroxide (H2O2) and generating highly reactive oxygen species through the Fenton reaction and enhanced POD-like activity, leading to the elimination of MCF-7 breast cancer cells via chemodynamic therapy. Furthermore, the incorporation of doxorubicin, an anticancer drug, into Fe3O4@NC nanozymes demonstrated a synergistic effect on chemo/chemodynamic cancer therapy. Concluded, the Fe3O4@NC nanozyme/nanocarrier exhibits considerable potential as an effective therapeutic agent for cancer cells, particularly when employed in conjunction with chemo/chemodynamic therapy. © 2025 Elsevier Ltd
Rezaie, H.,
Abbasi kajani, A.,
Jafarian, F.,
Asgari, S.,
Taheri kafrani, A.,
Bordbar, A. Journal of Biotechnology (01681656)387pp. 23-31
Enzyme immobilization in membrane bioreactors has been considered as a practical approach to enhance the stability, reusability, and efficiency of enzymes. In this particular study, a new type of hybrid membrane reactor was created through the phase inversion method, utilizing hybrid of graphene oxide nanosheets (GON) and polyether sulfone (PES) in order to covalently immobilize the Candida rugosa lipase (CRL). The surface of hybrid membrane was initially modified by (3-Aminopropyl) triethoxysilane (APTES), before the use of glutaraldehyde (GLU), as a linker, through the imine bonds. The resulted enzymatic hybrid membrane reactors (EHMRs) were then thoroughly analyzed by using field-emission scanning electron microscopy (FE-SEM), contact angle goniometry, surface free energy analysis, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, attenuated total reflection (ATR), and energy-dispersive X-ray (EDX) spectroscopy. The study also looked into the impact of factors such as initial CRL concentration, storage conditions, and immobilization time on the EHMR's performance and activity, which were subsequently optimized. The results demonstrated that the CRLs covalently immobilized on the EHMRs displayed enhanced pH and thermal stability compared to those physically immobilized or free. These covalently immobilized CRLs could maintain over 60% of their activity even after 6 reaction cycles spanning 50 days. EHMRs are valuable biocatalysts in developing various industrial, environmental, and analytical processes. © 2024 Elsevier B.V.
Food Chemistry (03088146)457
The escalating oxidative stress has heightened the daily human demand for diverse antioxidants. Therefore, development of the novel approaches to assess the total antioxidant capacity (TAC) of various nutrients is essential. In this study, drawing inspiration from the active site of native peroxidase enzymes, a novel peroxidase (POD)-like nanozyme was developed based on the cobalt ferrite (CoFe2O4) nanoparticles functionalized with different catalytic amino acids. Based on the TMB/H2O2 colorimetric system, the most substantial enhancement in POD-like activity was obtained by the glutamic acid coating among different charged amino acids studied, with more than 74% increase in specific activity compared to the bare CoFe2O4. A signal-off colorimetric sensing platform based on the obtained nanobiocatalyst was developed for the accurate quantification of the antioxidant capacity of phenolic compounds and vitamin C. The sensitive and selective quantification of ascorbic acid, tannic acid, gallic acid, cyanidin-3-glucoside, and quercetin was obtained by this colorimetric method. © 2024 Elsevier Ltd
Soozanipour, A.,
Ejeian, F.,
Razmjou, A.,
Asadnia, M.,
Nasr-esfahani, M.H.,
Taheri kafrani, A. ACS Applied Nano Materials (25740970)7(15)pp. 17262-17277
The condensed extracellular matrix (ECM) surrounding cancer cells results in the formation of a biophysical barrier versus chemotherapeutic drug penetration into deeper regions of many solid malignancies. To cope with this drawback, the present study inquired the therapeutic potential of a hyaluronidase (Hyal)-modified hyperbranched poly(amide amine) (PAMAM) loaded with an anticancer drug, methotrexate (MTX), to improve breast cancer chemoresistance. The focus is on reducing the hyaluronic acid accumulation as a major component of the tumor ECM. The decoration of the prepared pH-responsive nanoplatform with a relatively low density layer of polyethylene glycol (PEG) improved its stability and performance. These processes were characterized by different instruments and an enzymatic activity assessment. Despite the short half-life of pristine hyaluronidase, the Hyal-immobilized nanoplatform displayed enhanced enzyme stability, especially against protease degradation, and prolonged half-life after incubation in human plasma. The MTX loaded into carboxylate nanocarrier (PAMAM-MTX/SA/Hyal/PEG) exhibited an outstanding ability for controlled release of MTX. The results of the hemolysis assay confirmed the good blood compatibility of the as-prepared nanoplatform. The cytotoxicity assessment of various nanoformulations using an MTS-based assay on MCF-7 and MCF-10A cell lines revealed that PAMAM-MTX/SA/Hyal/PEG was more efficient against tumor cells than free MTX over 72 h. In addition, the effect of PAMAM-MTX/SA/Hyal/PEG against MCF-7 cells showed noteworthy induction of apoptosis and facilitated uptake by MCF-7 cells and penetration in MCF-7 3D tumor spheroids compared to free MTX. Thus, the synthesized nanoplatform indicated in vitro controlled release of MTX with the advantage of an adjuvant Hyal-based nanosystem. This outlook suggests a novel multifunctional nanoplatform to improve anticancer drug delivery systems by effective modulation of the tumor microenvironment. © 2024 American Chemical Society.
Journal of Biotechnology (01681656)394pp. 1-10
Biocatalytic membranes have great potential in various industrial sectors, with the immobilization of enzymes being a crucial stage. Immobilizing enzymes through covalent bonds is a complex and time-consuming process for large-scale applications. Polydopamine (PDA) offers a more sustainable and eco-friendly alternative for enzyme immobilization. Therefore, surface modification with polydopamine as mussel-inspired antifouling coatings has increased resistance to fouling. In this study, α-amylase enzyme was covalently bound to a bioactive PDA-coated polyethersulfone (PES) membrane surface using cyanuric chloride as a linker. The optimal activity of α-amylase enzyme immobilized on PES/PDA membrane was obtained at temperature and pH of 55°C and 6.5, respectively. The immobilized enzyme can be reused up to five reaction cycles with 55 % retention of initial activity. Besides, it maintained 60 % of its activity after being stored for five weeks at 4°C. Additionally, the immobilized enzyme demonstrated increased Michaelis constant and maximum velocity values during starch hydrolysis. The results of the biofouling experiment of various membranes in a dead-end cell demonstrated that the PES membrane's water flux increased from 6722.7 Lmh to 7560.2 Lmh after PDA modification. Although α-amylase immobilization reduced the flux to 7458.5 Lmh due to enhanced hydrophilicity, compared to unmodified membrane. The findings of this study demonstrated that the membrane produced through co-deposition exhibited superior hydrophilicity, enhanced coating stability, and strong antifouling properties, positioning it as a promising candidate for industrial applications. © 2024 Elsevier B.V.
Journal of Drug Delivery Science and Technology (17732247)100
Up to now, the existence of a safe and proper nanocarrier to improve the delivery efficiency of plasmid DNA into cells is a challenge. The large surface area and adjustable architectures of metal-organic framework (MOF), have gained a lot of interest and great potential for gene delivery. Herein, the Zirconium-Fumarate MOF (MOF-801) as novel MOF-polymer hybrid nanocarrier with high ability to gene delivery, was synthesized and modified with saponin- and fluorine-functionalized polyethyleneimine through an electrostatic interaction. The size and zeta potential of polyplex (DNA/nanocarrier) was 102 nm and +40 mV, respectively. Not only these powerful nanocarrier transfect the green fluorescent protein (plasmid-non encoded CRISPR/Cas systems) expression plasmid into the cell with an efficiency of about 60 %, but also, they showed good transfection efficiency at low plasmid doses and in existence of 30 % fetal bovine serum. Also, the nanocarrier was applied to study the plasmid delivery into cancer cell lines including MDA, PC12, HCT119, NIHT3, and MCF7 cells. The novel vector displayed low toxicity compared to other vectors which could be utilized for in vivo studies. Therefore, the saponin- and fluorine-modified polyethyleneimine/functionalized MOF-801 nanocomplex with remarkable properties was recommended for efficient gene transference. © 2024 Elsevier B.V.
An efficient enhancement in fruit juice quality achieves by simultaneously hydrolyzing polysaccharides in one pot reaction. Herein, an efficient approach is reported to fabricate a novel nanobiocatalyt for clarification of fruit juices based on covalent co-immobilization of pectinase and xylanase onto functionalized iron oxide nanoparticles. The highest activity recovery of the co-immobilized enzymes was achieved at 0.5 mg/mL of total protein, 8:1 w/w pectinase to xylanase ratio, and 6 h incubation time. Thermal and pH stabilities studies showed improved performance of co-immobilized enzymes compared to free counterparts. The co-immobilized pectinase and xylanase respectively retained more than 74% and 48% of residual activity after six consecutive cycles. Moreover, 53% turbidity reduction in pineapple juice was achieved after 120 min treatment with developed nanobiocatalyst. Besides, more than 64% of the initial activity of enzymes was retained after nine reuses, suggesting that this bi-enzyme nanobiocatalyst has potential application in industrial juice processing. © 2023 The Authors
Journal of Drug Delivery Science and Technology (17732247)81
Owing to elegant biomacromolecule features, proteins have been investigated to prepare a multifunctional and targeted nanoscale drug delivery systems. In this work, a novel cationic protein based nanocarrier, AS1411 aptamer-conjugated poly-L-lysine/β-lactogolubolin nanoparticles (BNP/PLL/Apt), was fabricated. The as-prepared nanocarrier offers an innovative formulation that combines the outstanding properties of protein nanocarriers and aptamer as a targeting agent for chemotherapy. To demonstrate the therapeutic potential of BNP/PLL/Apt, the nanocarriers were loaded with doxorubicin (DOX). The DOX-loaded BNP/PLL/Apt (BNP@DOX/PLL/Apt) exhibited high drug encapsulation efficiency, as high as 92%, and the controlled drug release profile in a mildly acidic physiological condition that could enhance therapeutic efficiency in cancerous cells. The in vitro assays of BNP@DOX/PLL/Apt illustrated that the synthesized drug delivery system was hemocompatible based on hemagglutination, coagulation and complement activation assay results. Besides, BNP@DOX/PLL/Apt was more potent against MCF-7 tumor cells than the free DOX. Thanks to the particular recognition between AS1411 aptamer and its receptor over-expressed on cancer cells, the BNP/PLL/Apt NPs show the enhanced cellular uptake in MCF-7 cells compared with the BNPs without aptameric modification. Moreover, the computational studies exhibited the reasonable binding affinity of β-lactogolubolin to DOX and activity of AS1411 aptamer against cancer cells which confirmed the experimental results. Overall, the resultants of this research possessed numerous advantages of BNP@DOX/PLL/Apt over free chemotherapy drugs and confirmed its great potential to address the clinical challenges observed in targeted anticancer drug delivery system. © 2023 Elsevier B.V.
Journal of Molecular Structure (00222860)1272
Elaidic acid (EA) is an unsaturated trans-fatty acid and one of the most important fatty acids obtained from solidifying vegetable oils. The increase in the consumption of EA is associated with rise and decline of LDL-cholesterol and HDL-cholesterol levels, respectively. It activates pro-inflammatory markers in the body and increases heart stroke and cardiovascular diseases. In this study, to understand the impact of EA in humans, we investigated the molecular interaction between EA and human serum albumin (HSA) and its binding affinity using spectroscopic, molecular dynamics (MD), and molecular docking techniques. According to fluorescence quenching experiments, EA could quench the inherent fluorescence of HSA via a static quenching mechanism. The thermodynamic characteristics of EA binding on HSA demonstrated hydrogen bonds and Van der Waals forces within the interaction, which matched molecular docking results. Further, the negative amount of ΔG° indicated the spontaneous binding of HSA to EA. Based on Förster's resonance energy transfer, the spatial distance between EA and HSA was 3.493 nm. The far-UV circular dichroism spectrum showed the decrease in the contents of the β-sheet and α-helix in the HSA structure. According to the RMSF data, the HSA structure's flexibility was diminished. The molecular dynamic simulation and spectroscopic studies also indicated that the binding interactions altered the milieu of the Trp chromophore and HSA structures. All experimental data could be matched with molecular dynamics simulation. © 2022 Elsevier B.V.
Experimental Eye Research (00144835)234
Bandage contact lenses have an increased affinity to accumulate tear film proteins and bacteria during wear. Among the wide variety of tear film proteins, lysozyme has attracted the most attention for several reasons, including the fact that it is found at a high concentration in the tear film, has exceptional antibacterial and antibiofilm properties, and its significant deposits onto contact lenses. This study aims to evaluate the effect of lysozyme on bacterial biofilm formation on bandage contact lenses. For this purpose, several methods, including microtiter plate test and Colony Forming Unit (CFU) assay have been used to determine antibacterial and antibiofilm characteristics of lysozyme against the two most frequent contact lens-induced bacterial ocular infections, Staphylococcus aureus, and Pseudomonas aeruginosa. The results of these assays demonstrate lysozyme potential to inhibit 57.9% and 80.7% of the growth of S. aureus and P. aeruginosa, respectively. In addition, biofilm formations of P. aeruginosa and S. aureus reduced by 38.3% and 62.7%, respectively due to the antibiofilm effect of lysozyme. SEM and AFM imaging were utilized to visualize lysozyme antibacterial activity and topography changes of the contact lens surface, respectively, in the presence/absence of lysozyme. The results indicated that lysozyme can efficiently attack both gram-positive and gram-negative bacteria and consequently lysozyme-functionalized bandage contact lenses can reduce the risk of ocular infection after eye surgery. © 2023 Elsevier Ltd
Journal of Molecular Liquids (01677322)387
Amongst various materials employed for modifying magnetic nanoparticles (MNPs), β-cyclodextrins (β-CDs) possess outstanding features for surface engineering of MNPs to improve the enzyme attachment. Herein, β-CD was modified onto MNPs and fabricated as a unique nanocarrier for the immobilization of xylanase. A variety of analytical techniques were applied to characterize the structural, morphological and chemical features of the as-prepared nanobiocatalyst. Notably, the xylanase immobilized onto the synthesized nanocomplex exhibited efficient reactivity and remarkable stability against harsh environmental condition. Besides, the as-prepared nanobiocatalyst could maintain 50 % of its original catalytic activity even after 12 successive reuses. The storage stability results showed that the free and immobilized xylanases lost approximately 65 % and 35 % of their original activity, respectively, after 90 days. The evaluation of kinetic metrics confirmed the remarkable improvement of immobilized xylanase performance. The effect immobilized xylanase on the reduction of apple and pineapple juices turbidity indicated that the turbidity decrease rate of apple juice occurred quickly (about 32 % in 90 min, for free and immobilized xylanases) rather than pineapple juice (about 20 % in 90 min, for both kinds of enzymes). The nanobiocatalyst also exhibited good recycling as approved by retention of 60 % and 70 % of relative activity after eight reuses in clarification of apple and pineapple juices. Additionally, the ability of immobilized xylanase to the extraction of antioxidant components demonstrated that the nanobiocatalyst can extract antioxidant outstandingly much higher than free enzyme. The resultants of this research indicates the great potential of the immobilized xylanase for employing in a wide range of bio-applications. © 2023 Elsevier B.V.
Journal of Molecular Liquids (18733166)349
In this work hyper-branched poly (amide amine) (PAMAM) nanoparticles were conjugated with hyaluronidase (Hyal) to produce a robust nano-biocatalyst for hyaluronic acid (HA) degradation. The success enzyme attachment process was confirmed by Fourier transform infrared (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), and UV–Vis. The influence of pH, temperature, and inhibitor on the enzymatic activity of hyaluronidase was also investigated. The optimum pH, temperature and storage time of Hyal-PAMAM nanocomplex were higher than free enzyme. Also, ascorbic acid showed more inhibitory effect on free enzyme, the IC50 values were determined to be around 55 ± 0.7 and 70 ± 0.3 mM for free Hyal and Hyal-PAMAM nanocomplex, respectively. Based on the greater υmax and lower Km, the Hyal-PAMAM showed a better catalytic efficiency for HA degradation. Moreover, the in silico screening of PAMAM/Hyal interactions further confirmed the experimental results. The novel strategy for combining Hyal and PAMAM dendrimer can hold great promise for applications in biomedical, sensing, and industrial catalysis. © 2021 Elsevier B.V.
Process Biochemistry (13595113)122pp. 95-104
Alpha-linolenic acid (ALA) is one of the necessary fatty acids for the human body. It is a precursor for synthesizing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The consumption of ALA as an anti-inflammatory factor plays a significant role in preventing cardiovascular diseases. The current study was investigated to evaluate the binding affinity and molecular interactions between human serum albumin (HSA) with ALA through spectroscopic and computational studies. In the existence of ALA, the absorbance of HSA is reduced, confirming the development of the HSA-ALA complex. The fluorescence spectroscopic data implied that the quenching mechanism for HSA-ALA interaction was static mode. The negative values of ΔH° and ΔS° indicated that hydrogen bonding and van der Waals are the predominant intermolecular forces in the complex between HSA and ALA. The binding of ALA induces changes in the structure of HSA, which were revealed by far-UV circular dichroism (CD). The reduction of root mean square deviation (RMSD) after binding to ALA proved the stability of the structure of HSA in the presence of ALA. The results of the esterase activity of HSA presented that ALA competitively binds with HSA. This study demonstrated the importance of ALA in medicine and emphasized its main pharmacological significance. © 2022 Elsevier Ltd
JAOCS, Journal of the American Oil Chemists' Society (0003021X)98(4)pp. 391-401
Chlorophyllase converts chlorophyll and pheophytin into their colorless derivatives (chlorophyllide/pheophorbide and phytol). This activity can be used in chlorophyll removal from vegetable oils. Chlorophyllase genes from Oscillatoria acuminata (OscChlase) and Citrus aurantium (CitChlase) were isolated, cloned, and expressed in E. coli. Bioinformatics analysis showed that both chlorophyllases shared a conserved GHSXG lipase motif responsible for their catalytic activity. SDS-PAGE and immunoblot assays revealed that both enzymes had a molecular weight of 35 kDa. The purified chlorophyllases were stable at a broad range of temperatures and showed the highest activity at 40 °C. OscChlase and CitChlase exhibited the highest activity at pH 6.0 and 7.0, respectively. Enzyme kinetics analysis revealed that OscChlase was able to hydrolyze bacteriochlorophyll-a more efficiently than the recombinant CitChlase (Vmax/Km of 0.38 for OscChlase vs. 0.01 min−1 mg protein for CitChlase). Instead, CitChlase hydrolyzed chlorophyll-b more efficiently than OscChlase. Both enzymes were able to reduce the chlorophyll content of olive (from 623.1 to as low as 87.2 mg per kg oil) and canola oil (from 537.2 to as low as 101.1 mg per kg oil). The ratio of oil to the aqueous reaction media affected chlorophyll hydrolysis (P < 0.05). The lower the oil ratio was (10%), the higher the chlorophyll removal was (75–86%). The efficiency of CitChlase in chlorophyll removal was higher than that of OscChlase at oil ratios of 10 and 20, but lower at 30% ratio (P < 0.05). This is the first report on the application of recombinant OscChlase and CitChlase in chlorophyll removal (up to 86%) from vegetable oils. © 2021 AOCS
Taheri kafrani, A.,
Shirzadfar, H.,
Abbasi kajani, A.,
Kudhair, B.K.,
Mohammed, L.J.,
Mohammadi, S.,
Lotfi, F. Journal of Biotechnology (01681656)331pp. 26-36
The development of efficient drug nanocarriers has remained an important challenge in advanced drug delivery in human body. Combination of graphene-based nanomaterials and cyanuric chloride (CC), as a linker, may improve the success of drug delivery. Herein, a simple approach was used for the synthesis of superparamagnetic graphene oxide (SPMGO) nanocomposite through a chemical precipitation method. The nanocomposite was readily functionalized with cyanuric chloride as a linker for loading the drug. The FTIR spectroscopy confirmed the efficient synthesis of nanocarriers. So did the transmission electron microscopy, atomic force microscopy, and thermo-gravimetric analysis, X-ray diffraction and X-ray photoelectron spectroscopy. Subsequently, the synthesized nanocarriers were studied in terms of their potential for biomedical applications. Immobilization of methotrexate (MTX), as a drug for treatment of cancer was taken into action on the SPMGO and SPMGO/CC. The in vitro assays indicated that the drug nanocarrier systems, SPMGO/MTX and SPMGO/CC/MTX, are hemo-compatible and increase the efficiency of MTX against Caov-4, HeLa and MCF-7 cell lines. The MTX nanocarriers represented a considerably high drug loading and controlled drug release. The overall results indicated the great potential of SPMGO/CC/MTX nanocarrier for targeted drug delivery, particularly in MTX chemotherapy. © 2021
Soozanipour, A.,
Sohrabi, H.,
Abazar, F.,
Khataee, A.,
Nurbakhsh, S.A.,
Asadnia, M.,
Taheri kafrani, A.,
Majidi, M.R.,
Razmjou, A. Advanced Materials Technologies (2365709X)6(10)
Nanochannels offer significant practical advantages in many fields due to their interesting characteristics, such as flexibility in shape and size, robustness, low-cost and their ability to be modified based on the required applications. The effectiveness of ion separation in nanochannels can be assessed based on the selective transport of the desired ions and the rate of the transportation process. This paper aims to provide an extensive review of ion-based nanochannels, including their working principles and ion-selective behaviors. Nanochannel fabrication strategies and their applications are discussed. Key nanochannel design factors and their roles in governing ion-selective transport are also reviewed. The contribution of size, charge, wettability, and recognition ability of the nanochannels on the selectivity mechanisms are discussed. Specific consideration is made to nanochannel applications in sensing and biosensing assays. Finally, an attempt is made to address the commercial implementation and future outlook of the nanochannels to guide researchers in emerging avenues of research. © 2021 Wiley-VCH GmbH
Emadi, E.,
Bordbar, A.,
Nadri, H.,
Shams, A.,
Taheri kafrani, A.,
Kalantar, S.M. RSC Advances (20462069)11(49)pp. 30990-31001
The development of an effective and noninvasive early method for obtaining fetal cells is crucial to prenatal screening. Despite proving the presence of fetal cells in the reproductive tract, their use is limited due to their inability to properly isolate them from maternal cells. Magnetic-activated cell sorting (MACS) is a simple technique to separate cells. The present study aimed to develop a MACS-based platform for the isolation of the HLA-G expressing trophoblast cells. For this purpose, first, the triazine functionalized MNPs were synthesized and characterized. Then, MNPs were directly and indirectly conjugated by the MEM-G/9 antibodies targeting HLA-G+ cells. The antibody amount on the surface of the nanoparticles was determined with the Bradford assay. The cell capture efficiency was also investigated. Various characterization methods confirmed the successful nanoparticle synthesis and antibody conjugation. The optimal initial antibody amount for the immobilization was about 20 μg and the optimal time was 3 h. The antibody-nanoparticles by the indirect method had better targeting and capture efficiency than the direct method. The MNPs indirectly conjugated with antibodies are an efficient tool for cell isolation and present considerable potential to be applied in biomedical fields. © 2021 The Royal Society of Chemistry.
Taheri kafrani, A.,
Kharazmi, S.,
Nasrollahzadeh, M.,
Soozanipour, A.,
Ejeian, F.,
Etedali, P.,
Mansouri-tehrani h.a., H.,
Razmjou, A.,
Yek, S.M.,
Varma, R.S. Critical Reviews in Food Science and Nutrition (10408398)61(19)pp. 3160-3196
The demand for food and beverage markets has increased as a result of population increase and in view of health awareness. The quality of products from food processing industry has to be improved economically by incorporating greener methodologies that enhances the safety and shelf life via the enzymes application while maintaining the essential nutritional qualities. The utilization of enzymes is rendered more favorable in industrial practices via the modification of their characteristics as attested by studies on enzyme immobilization pertaining to different stages of food and beverage processing; these studies have enhanced the catalytic activity, stability of enzymes and lowered the overall cost. However, the harsh conditions of industrial processes continue to increase the propensity of enzyme destabilization thus shortening their industrial lifespan namely enzyme leaching, recoverability, uncontrollable orientation and the lack of a general procedure. Innovative studies have strived to provide new tools and materials for the development of systems offering new possibilities for industrial applications of enzymes. Herein, an effort has been made to present up-to-date developments on enzyme immobilization and current challenges in the food and beverage industries in terms of enhancing the enzyme stability. © 2020 Taylor & Francis Group, LLC.
Journal of Chemical Technology and Biotechnology (02682575)95(8)pp. 2243-2250
BACKGROUND: Widespread application of enzymes for research and industrial purposes is dependent on enhancing the catalytic capacity. One promising approach to this end is the immobilization of enzymes on novel nanomaterials. In this study, a novel nanocarrier was developed for the immobilization of enzyme on polycaprolactone (PCL)-functionalized magnetic nanoparticles. RESULT: Structural and physicochemical characterization of the PCL-modified magnetic nanocarrier was achieved via Fourier-transform infrared (FTIR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and vibration sample magnetometry (VSM). In order to determine the optimal conditions for immobilization, different parameters such as pH, temperature, reaction time and enzyme concentration were evaluated. Based on the results, the optimal biocatalytic activity of immobilized α-amylase was obtained at 65 °C and pH 6.5. Under appropriate conditions, the immobilized α-amylase showed improved storage stability in comparison with free one. Additionally, the reusability of the immobilized system demonstrated >50% enzyme activity, at optimal pH and temperature, after five reaction cycles. CONCLUSION: This finding could be useful in the application of immobilized enzymes for analytical purposes, industrial exploitations, biotechnology, biomedical engineering and other bio-applications. © 2020 Society of Chemical Industry. © 2020 Society of Chemical Industry
Zare-zardini, H.,
Alemi, A.,
Taheri kafrani, A.,
Hosseini, S.A.,
Soltaninejad, H.,
Hamidieh, A.A.,
Karamallah, M.H.,
Farrokhifar, M.,
Farrokhifar, M. Drug Design, Development and Therapy (11778881)14pp. 3315-3324
Introduction: Ginsenoside Rh2, purified from the Panax ginseng root, has been demonstrated to possess anticancer properties against various cancerous cells including colorectal, breast, skin, ovarian, prostate, and liver cancerous cells. However, the poor bioavailability, low stability on gastrointestinal systems, and fast plasma elimination limit further clinical applications of Ginsenoside Rh2 for cancer treatments. In this study, a novel formulation of niosomal Ginsenoside Rh2 was prepared using the thin film hydration technique. Methods: The niosomal formulation contained Span 60 and cholesterol, and cationic lipid DOTAP was evaluated by determining particle size distribution, encapsulation efficiency, the polydispersity index (PDI), and surface morphology. The cytotoxic effects of free Ginsenoside Rh2 and Ginsenoside Rh2-loaded niosomes were determined using the MTT method in the PC3 prostate cancer cell line. For the investigation of the in vitro cellular uptake of Ginsenoside Rh2-loaded niosome, two formulations were prepared: the Ginsenoside Rh2-loaded niosomal formula containing 5% DOTAP and the Ginsenoside Rh2-loaded niosomal formula without DOTAP. Results: The mean size, DPI, zeta potential, and encapsulation efficiency of the Ginsenoside Rh2-loaded nanoniosomal formulation containing DOTAP were 93.5±2.1 nm, 0.203±0.01, +4.65±0.65, and 98.32% ±2.4, respectively. The niosomal vesicles were found to be round and have a smooth surface. The release profile of Ginsenoside Rh2 from niosome was biphasic. Furthermore, a two-fold reduction in the Ginsenoside Rh2 concentration was measured when Ginsenoside Rh2 was administered in a nanoniosomal form compared to free Ginsenoside Rh2 solutions in the PC3 prostate cancer cell line. After storage for 90 days, the encapsulation efficiency, vesicle size, PDI, and zeta potential of the optimized formulation did not significantly change compared to the freshly prepared samples. The cellular uptake experiments of the niosomal formulation demonstrated that by adding DOTAP to the niosomal formulation, the cellular uptake was enhanced. Discussion: The enhanced cellular uptake and cytotoxic activity of the Ginsenoside Rh2 nanoniosomal formulation on the PC3 cell make it an attractive candidate for application as a nano-sized delivery vehicle to transfer Ginsenoside Rh2 to cancer cells. © 2020 Zare-Zardini et al.
Separation and Purification Technology (13835866)237
Staphylococcus aureus and Staphylococcus epidermidis are considered as major human pathogens and their resistance to antibiotic treatment and host defense systems can be increased due to the formation of biofilms. The biofilm-associated biofouling of industrial surfaces, particularly membranes, remains a serious concern that challenges investigators to develop practical solutions for the reduction of their impact. The present study developed antibacterial membrane surfaces that can mitigate biofilm formation. α-Amylase and lysozyme, as antibacterial enzymes, were covalently immobilized on polydopamine/cyanuric chloride functionalized polyethersulfone (PES) membranes to form biocompatible antibacterial surfaces. Several methods including SEM, AFM, Bradford, water contact angle goniometry, and surface free energy measurement techniques have been used to demonstrate the attachment of enzymes onto PES membranes by changing the physicochemical properties of the surface. The two enzymatic systems alter the membrane surface chemistry by rendering lower free surface energy and higher hydrophilicity, which leads to the creation of a layer of hydration energy barrier preventing microorganisms from being anchored on the surface. Those microorganisms that managed to overcome the energy barrier and get attached to the surface are attached by the enzymes' bond cleavage functionality. This multilevel defense system protects the membrane against any biofilm formation. The results of microtiter test and flow cytometry assay indicated that α-amylase/lysozyme mixture treated membrane samples came with more than 87% removal of biofilms. The results of the biofouling experiment in a dead-end cell demonstrated that the modified membrane surface had only a slightly impaired water flow compared to an unmodified membrane, which was due to the removal of biofilms by the enzymes’ activity. The results also showed that the modification of membranes with antibacterial enzymes could create a new biotechnological horizon to prevent biofilm formation. © 2019 Elsevier B.V.
Journal of Biomimetics, Biomaterials and Biomedical Engineering (22969837)47pp. 63-74
Electrospun fibers have demonstrated a remarkable potential as a framework structure in the fabrication of cartilage tissue engineering (CTE) scaffolds. Various extracellular matrices have been incorporated into electrospun scaffolds to mimic and simulate the extracellular environment. The objective of this study was to fabricate hybrid constructs using composite electrospun scaffolds based on poly (ε-caprolactone) (PCL) and cartilage-derived matrix (CDM) and fibrin hydrogel to improve the viability and differentiation of human adipose-derived stromal cells (ADSCs) for CTE applications. Initially, PCL and PCL-CDM electrospun mats were fabricated. Fibrin/ ADSCs hydrogel were seeded on PCL-CDM mats and arranged layer-by-layer using sandwich technique. This method has been employed to increase cell seeding and infiltration efficiency through the entire mass of the scaffold. Real-time reverse-transcription polymerase chain reaction (RT-PCR), were performed to examine the expression of collagen types II and X, SOX9 and aggrecan. The production of glycosaminoglycan (GAG) was also tested in vitro by Toluidine blue stain and biochemical assay in the cultured scaffolds. The findings demonstrated that incorporation of CDM in PCL fibers results in improved cell viability. Hematoxylin and eosin staining showed that the sandwich method resulted in homogenous cell seeding within the scaffold. Overall, the RT-PCR, biochemical and histological results, showed that incorporation of the CDM into PCL/fibrin sandwich scaffolds stimulated ADSCs chondrogenesis and produced the products which increased expression of chondrogenic genes. It also, enhanced GAG synthesis compared to PCL/fibrin scaffolds. These findings suggest PCL-CDM/fibrin can be considered as an appropriate hybrid scaffold for CTE applications. © 2020 Trans Tech Publications Ltd, Switzerland.
Molecular Biology Reports (03014851)47(4)pp. 2677-2684
Glutathione-S-transferases (GSTs) play a role in the detoxification of environmental chemicals and mutagens, such as those inhaled during tobacco smoking. There have been conflicting reports concerning GST polymorphisms as risk factors in the development of lung cancer. No studies focused on Arab populations exposed to Waterpipe (WP) tobacco smoke have been undertaken. Here Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and gene sequencing were applied to analyze allelic variations in GSTP1-rs1695 and -rs1138272 amongst 123 lung cancer patients and 129 controls. The data suggest that WP smoking raised the risk of lung cancer more than three-fold (OR 3.6; 95% CI 2.1–6.0; p < 0.0001). However, there was no significant association between individual GSTP1 polymorphisms and the risk of lung cancer. In contrast, analysis of the rs1695 and rs1138272 combination suggested that the risk of lung cancer was raised more than two-fold for carriers of the GSTP1-rs1695 (G) allele (OR 2.5; 95% CI 1.0–6.4; p < 0.05), however, the presence of the GSTP1-rs1138272 (T) allele, in addition to GSTP1-rs1695, did not significantly change the risk ratio (OR 2.8; 95% CI 1.4–5.7; p < 0.004). WP tobacco smokers who carried the GSTP1-rs1695, but not GSTP1-rs1138272, allele were similarly susceptible to lung cancer (OR 2.4; 95% CI 1.1–5.3; p < 0.03). Hence, the results suggest that smoking WP tobacco and carrying GSTP1-rs1695 polymorphisms are risk factors for lung cancer in Arab Iraqi males. © 2020, Springer Nature B.V.
Advanced Materials Interfaces (21967350)7(13)
Developing a facile approach for the manipulation of the direction and order of the enzymatic reactions via sequential immobilization on inexpensive substrates is a continuous demand. Herein, a new methodology is introduced that allows making a desired enzymatic reaction pathway on a paper-based microfluidic-membrane based biosensor (P-µMB). Although the method is universal, here, as a proof-of-concept, the sequential immobilization of α-amylase, glucose oxidase (GOx) and horseradish peroxidase (HRP) is presented for fabricating a P-µMB. To this end, hydrophilic polydopamine/polyethyleneimine patterns are created on the hydrophobic polypropylene membrane using 3D printing and a polydimethylsiloxane (PDMS) mold, and a coating layer of silver nanoparticles (AgNPs) is used to modify the patterns. The enzymes are then individually immobilized on the desired locations with another set of PDMS molds. It is observed that AgNPs P-µMB in the sequential immobilization system has stable activity at various temperature and pH regimes, high selectivity toward starch, wide-range linear sensitivity, and a limit of detection of 0.002% w/w starch. A smartphone camera is used for the quantitative analysis of the analyte with the mean gray intensity as the analytical parameter. This developed system provides a platform for further sequential immobilization of other types of biological elements. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Food Chemistry (03088146)325
Developing an effective strategy to economically exploitation of pectinase, as one of the most widely used enzymes in food industry, is of utmost importance. Herein, pectinase was covalently immobilized onto polyethylene glycol grafted magnetic nanoparticles via trichlorotriazine with high loading efficiency. The generated immobilized pectinase showed enhanced catalytic activity, improved operational stability, and easily reusability. Thermal and pH stabilities studies showed improved performance of immobilized pectinase especially at extreme points. Compared to free enzyme, the noticeably lower Km and higher vmax values of immobilized pectinase demonstrated the enhanced catalytic activity of this enzyme after immobilization. Besides, the immobilized enzyme exhibited excellent reusability and stability by retaining up to 55 and 94% of its initial activity after 10 recycles and 125 days storage at 25 °C, respectively. Moreover, turbidity reduction occurred up to 59% in treated pineapple juice with immobilized pectinase, suggesting applicability of this system in juice and food-processing industries. © 2020 Elsevier Ltd
Carbohydrate Polymers (01448617)232
A greener, cost efficient and simple method is described to prepare copper nanoparticles (NPs) immobilized on the magnetic chitosan (one of the more versatile polysaccharides) using Euphorbia falcata leaf extract as reducing/stabilizing agent. The prepared catalyst (Cu NPs@Fe3O4-chitosan) was authenticated by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetry/derivative thermogravimetry (TG/DTG), Vibrating sample magnetometer (VSM), and elemental mapping. TEM analysis indicates that Cu NPs with average sizes in 5−10 nm range is formed on magnetic chitosan with the spherical morphology. The Cu NPs@Fe3O4-chitosan was employed as a new catalyst for the synthesis of different tetrazoles by the reaction of various secondary or tertiary cyanamides with sodium azide in water under reflux conditions. Easy separation by external magnetic field, mild reaction conditions, low cost and the reusability are some of the beneficial features of this catalyst. © 2019 Elsevier Ltd
Chemosphere (00456535)249
The development of stable and effective iodine removal systems would be highly desirable in addressing environmental issues relevant to water contamination. In the present research, a novel iodine adsorbent was synthesized by self-polymerization of dopamine (PDA) onto inert polypropylene (PP) membrane. This PP/PDA membrane was thoroughly characterized and its susrface propeties was analyzed by various analytical techniques indcluding field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH), contact angle, and surface free energy measurement. The PP/PDA membranes were subsequently used for batchwise removal of iodine at different temperatures (25–70 °C), pH (2–7), and surface areas (1–10 cm2) to understand the underlying adsorption phenomena and to estimate the membrane capacity for iodine uptake. The increase in temperature and pH both led to higher adsorption of iodine. The present approach showed a removal efficiency of over 75% for iodine using 10 cm2 PP/PDA membrane (18.87 m2 g−1) within 2 h at moderate temperatures (∼50 °C) and pH > 4, about 15 fold compared to the PP control membrane. The adsorption kinetics and isotherms were well fitted to the pseudo-second-order kinetic and Langmuir isotherm models (R2 > 0.99). This adsorbent can be recycled and reused at least six times with stable iodine adsorption. These findings were attributed to the homogenous monolayer adsorption of the iodide on the surface due to the presence of catechol and amine groups in the PP/PDA membrane. This study proposes an efficient adsorbent for iodine removal. © 2020 Elsevier Ltd
Molecular Biology Reports (03014851)47(7)pp. 5155-5163
Genetic polymorphisms of genes whose products are responsible for activities, such as xenobiotic metabolism, mutagen detoxification and DNA-repair, have been predicted to be associated with the risk of developing lung cancer (LC). The association of LC with tobacco smoking has been extensively investigated, but no studies have focused on the Arab ethnicity. Previously, we examined the association between genetic polymorphisms among Phase I and Phase II metabolism genes and the risk of LC. Here, we extend the data by examining the correlation of OGG1 Ser326Cys combined with CYP1A1 (Ile462Val and MspI) and GSTP1 (Ile105Val and Ala103Val) polymorphisms with the risk of LC. Polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) and gene sequencing were carried out for genotyping the OGG1 polymorphisms of 123 LC patients and 129 controls. No significant differences in the frequencies of the OGG1 mutant allele between patients and controls were found. The distributions of heterozygous Ser/Cys or Cys/Cys genotypes of OGG1 were not associated with the risk of LC either according to the histological types of LC or based on waterpipe tobacco (WP) smoking status. In contrast, the combined effect of OGG1 variants with CYP1A1 and GSTP1 variants revealed a significant correlation with the OGG1 Ser326Cys—CYP1A1 MspI variants pairing. This association was significant (p = 0.001) in individuals who carried homozygous or heterozygous variant type genotypes of both genes in a reference with carriers of both wild-type genotypes (wt/wt − wt/wt). The odds ratios were 2.99 (95% CI 1.67–5.36), 2.68 (95% CI 1.08–6.62), and 2.80 (95% CI 1.18–6.69) for those who carried (wt/wt − wt/vt + vt/vt), (wt/vt + vt/vt − wt/wt), and (wt/vt + vt/vt − wt/vt + vt/vt), respectively. The study suggests a limited correlation is present between carrying OGG1 Ser326Cys polymorphism and the risk of developing LC in Arab populations. © 2020, Springer Nature B.V.
International Journal of Biological Macromolecules (01418130)163pp. 402-413
The covalent immobilization of xylanase onto the trichlorotriazine-functionalized polyethylene glycol grafted magnetic nanoparticles was exploited to generate a stabilized xylanase with improved catalytic activity and stability. Several tools were deployed to monitor the synthesis and immobilization processes, the loading capacity of nanocarrier, and the structural/chemical characteristics of the nanobiocatalyst. The optimum immobilization yield of xylanase was 260 mg xylanase/g nanocarrier in 20 mM phosphate buffer, pH 6.5 at 25 °C. A forward shift in optimum pH (6.5 to 7.5) and temperature (60 to 70 °C) of xylanase was observed after immobilization and the performance of immobilized enzyme was improved at high temperatures and pHs as affirmed by enhancement of vmax (2.69 to 6.01 U/mL) and decreases of Ea (14.61 to 13.41 kJ/mol). An increase in Km from 25.51 to 40.42 mg/mL was recorded after immobilization. The obtained results indicated augmented thermal stability of the immobilized xylanase. Notably, it showed good reusability as validated by retention of 50% of its initial activity after nine recycles in enrichment of the pineapple juice clarification after 120 min incubation at 50 °C, pH 4.5. The structural analysis revealed some partial changes in the α-helix and β-sheet content of the enzyme after several recycles. © 2020 Elsevier B.V.
Journal Of The Iranian Chemical Society (1735207X)16(1)pp. 21-31
Abstract: Today, immobilization of enzymes has been extensively considered in a wide variety of applications in industries. Xylanase is a hemicellulotic enzyme with effective usages that has attracted the attention of researchers. In this work, xylanase from Thermomyces lanuginosus was covalently immobilized on modified graphene oxide nanosheets (NGO) via cyanuric chloride linker. The magnetic nanoparticles were perched on NGO to facilitate separation of nanocarrier from the reaction media. To decrease the steric hindrance and allow the high-molecular weight xylan as a substrate to approach the active site of the immobilized xylanase, polyethylene glycol bis-amine was used as a spacer. Various techniques such as TEM, SEM, FTIR, VSM and TGA were applied to characterize the structure of synthetic nanocomposite. The amount of immobilized xylanase was quantified by Bradford assay, and the immobilization efficiency was determined about 67%. The results showed that thermal stability, pH stability, reusability and storage stability were improved for immobilized enzyme and the kinetic parameters, Km and vmax values, were increased, suggesting the great potential of the functionalized NGO as a novel nanocarrier in bio-industry applications. Graphical abstract: [Figure not available: see fulltext.]. © 2018, Iranian Chemical Society.
Applied Biochemistry and Biotechnology (02732289)187(2)pp. 649-661
β-Lactoglobulin (BLG), a member of lipocalin family, is one of the major bovine milk allergens. This protein exists as a dimer of two identical subunits and contains two intramolecular disulfide bonds that are responsible for its resistance to trypsin digestion and allergenicity. This study aimed to evaluate the effect of reduction of disulfide bonds of BLG with different rice thioredoxins (Trxs) on its digestibility and allergenicity. Therefore, the active recombinant forms of three rice Trx isoforms (OsTrx1, OsTrx20, and OsTrx23) and one rice NADPH-dependent Trx reductase isoform (OsNTRB) were expressed in Escherichia coli. Based on SDS-PAGE, HPLC analysis, and competitive ELISA, the reduction of disulfide bonds of BLG with OsNTRB/OsTrx23, OsNTRB/OsTrx1, GSH/OsTrx1, or GSH/OsTrx20 increased its trypsin digestibility and reduced its immunoreactivity. The finding of this study opens new insights for application of plant Trxs in the improvement of food protein digestibility. Especially, the use of OsTrx20 and OsTrx1 are more cost-effective than E. coli and animal Trxs due to their reduction by GSH and no need to NADPH and Trx reductase as mediator enzyme. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
Setayeshmehr, M.,
Esfandiari, E.,
Rafienia m., M.,
Hashemibeni, B.,
Taheri kafrani, A.,
Samadikuchaksaraei, A.,
Kaplan, D.L.,
Moroni, L.,
Joghataei, M.T. Tissue Engineering - Part B: Reviews (19373368)25(3)pp. 202-224
Cartilage consists of chondrocytes and a special extracellular matrix (ECM) having unique biochemical, biophysical, and biomechanical properties that play a critical role in the proliferation and differentiation of cells inherent to cartilage functions. Cartilage tissue engineering (CTE) requires recreating these microenvironmental physicochemical conditions to lead to chondrocyte differentiation from stem cells. ECM-derived hybrid scaffolds based on chondroitin sulfate, hyaluronic acid, collagen, and cartilage ECM analogs provide environments conducive to stem cell proliferation. In this review, we describe hybrid scaffolds based on these four cartilage ECM derivatives; we also categorize these scaffolds based on the methods used for their preparation. The use of hybrid scaffolds is increasing in CTE to address the complexity of cartilage tissue. Thus, a comprehensive review on the topic should be a useful guide for future research. Scaffolds fabricated from extracellular matrix (ECM) derivatives are composed of conducive structures for cell attachment, proliferation, and differentiation, but generally do not have proper mechanical properties and load-bearing capacity. In contrast, scaffolds based on synthetic biomaterials demonstrate appropriate mechanical strength, but the absence of desirable biological properties is one of their main disadvantages. To integrate mechanical strength and biological cues, these ECM derivatives can be conjugated with synthetic biomaterials. Hence, hybrid scaffolds comprising both advantages of synthetic polymers and ECM derivatives can be considered a robust vehicle for tissue engineering applications. © Copyright 2019, Mary Ann Liebert, Inc., publishers 2019.
Journal of Biotechnology (01681656)298pp. 88-97
Polymer-coated nanocarriers play an important role in targeted drug delivery. The use of polymers such as polyethylene glycol increases stability, biocompatibility, and blood circulation time of the drug, and may consequently improve the success of drug delivery. In the present work, a simple approach has been reported for synthesizing polyethylene glycol bis amin (PEGA) functionalized graphene oxide/iron oxide nanocomposite as a remarkable unit for loading drugs. The biomedical applications of the synthesized nanocomposite were investigated by immobilizing methotrexate (MTX), as an anticancer drug. The structural and morphological characteristics and the successful synthesis of the nanocomposite were evaluated by different charachterization techniques. The cytotoxicity assay of the nanocarrier showed higher toxicity against HeLa and MCF-7 cell lines, compared to free MTX. The drug release experiments in acidic and physiological conditions suggested the first order kinetics model for the release of MTX from the nanocomposite. Furthermore, the agglutination, complement activation, and coagulation time experiments demonstrated the blood compatibility of the synthesized nanocarrier. © 2019 Elsevier B.V.
Journal of Colloid and Interface Science (00219797)536pp. 261-270
In industrial processes, effective degradation of polygalacturonic acid using immobilized pectinase is preferred over free one due to its stability and efficient functional reuses. Pectinase was covalently conjugated to the surface of cyanuric chloride functionalized chitosan encapsulated magnetite nanoparticles. The results obtained of various analytical tools and biochemical studies demonstrated successful synthesis and immobilization processes, high immobilization efficiency and loading capacity. The circular dichroism (CD) results of free and immobilized pectinase revealed the partial decreases in the α-helices and β-sheets, and marginal increases in the unordered elements contents of pectinase upon the immobilization onto Fe3O4@Ch-CC nanoparticles, along with stability improvement. The immobilized pectinase was retained about 60% of its initial catalytic activity after 13 recycles at optimum conditions (40 °C, pH 4.5). The storage stability of pectinase was increased due to immobilization, after 75 days storage at 4 °C, the free and immobilized enzyme retained 43% and 74% of the initial activity, respectively. The immobilized pectinase showed higher storage stability and better performance at wider ranges of pH and temperature, compared to free pectinase. © 2018 Elsevier Inc.
Doustkhah, E.,
Najafi zare, R.,
Yamauchi, Y.,
Taheri kafrani, A.,
Mohtasham, H.,
Esmat, M.,
Ide, Y.,
Fukata, N.,
Rostamnia, S.,
Sadeghi m., M.H. Journal of Materials Chemistry B (2050750X)7(45)pp. 7228-7234
The design of hydroxyapatite (HA) nanoarchitecture is critical for fabricating artificial bone tissues as it dictates the biochemical and the mechanical properties of the final product. Herein, we incorporated a simple hard-template approach to synthesise single crystal nanoplates of HA. We used the 2D graphitic nitride (g-C3N4) material to prepare an HA sol-gel under hydrothermal conditions. A new HA nanostructure was then formed during the calcination and removal of g-C3N4 at a higher temperature, which finally led to the production of nanoplates (thickness of ∼100 nm) while in lateral dimension the average size was in the micrometre scale. We characterised the synthesised HA nanoplates with XRD, TEM, and HRTEM. The theoretically predicted nanostructure construction based on Wulff's method is in full agreement with the experimental observations. We then prepared different weight ratios of HA and polylactic acid (PLA) composites for artificial 3D bone fabrication. The strong interaction between PLA and HA's (110) facet, which was the second most prevalent, resulted in the composite's mechanical robustness. After mechanical testing, an optimum ratio was selected for biological studies and 3D printing. Biological experiments demonstrated that the synthesised composite had excellent viability in vitro. © 2019 The Royal Society of Chemistry.
International Journal of Biological Macromolecules (01418130)112pp. 876-881
Nowadays health benefits of bioactive food constituents, known as probiotic microorganisms, are a growing awareness. Cow's milk is a nutritious food containing probiotic bacteria. However, milk allergenicity is one of the most common food allergies. The milk protein, beta-lactoglobulin (BLG), is in about 80% of all main cases of milk allergies for children and infants. With the aim of screening proteolytic strains of lactic acid bacteria to evaluate their potential for the reduction of allergenicity of the major bovine milk proteins, we isolated new proteolytic strains of cocci lactic acid bacteria from traditional Iranian daily products. The proteases produced by these strains had strong proteolytic activity against BLG. Proteolysis of BLG, observed after sodium dodecyl sulfate PAGE, was confirmed by the analysis of the peptide profiles by reversed-phase HPLC. The two isolates were submitted to 16S rDNA sequencing and identified as Lactcoccus lactic subsp. cremoris and Lactcocrus lactic subsp. hordniea. The competitive ELISA experiments confirmed that these isolates, with high proteolytic activity, reduce significantly the allergenicity of BLG. Accordingly, these isolates can reduce the immunoreactivity of bovine milk proteins, which can be helpful for the production of low-allergic dairy products. (C) 2018 Elsevier B.V. All rights reserved.
International Journal of Biological Macromolecules (01418130)
Nowadays health benefits of bioactive food constituents, known as probiotic microorganisms, are a growing awareness. Cow's milk is a nutritious food containing probiotic bacteria. However, milk allergenicity is one of the most common food allergies. The milk protein, β-lactoglobulin (BLG), is in about 80% of all main cases of milk allergies for children and infants. With the aim of screening proteolytic strains of lactic acid bacteria to evaluate their potential for the reduction of allergenicity of the major bovine milk proteins, we isolated new proteolytic strains of cocci lactic acid bacteria from traditional Iranian dairy products. The proteases produced by these strains had strong proteolytic activity against BLG. Proteolysis of BLG, observed after sodium dodecyl sulfate-PAGE, was confirmed by the analysis of the peptide profiles by reversed-phase HPLC. The two isolates were submitted to 16S rDNA sequencing and identified as Lactcoccus lactis subsp. cremoris and Lactcoccus lactis subsp. hordniea. The competitive ELISA experiments confirmed that these isolates, with high proteolytic activity, reduce significantly the allergenicity of BLG. Accordingly, these isolates can reduce the immunoreactivity of bovine milk proteins, which can be helpful for the production of low-allergic dairy products. © 2018 Elsevier B.V.
Ejeian, F.,
Etedali, P.,
Mansouri-tehrani h.a., H.,
Soozanipour, A.,
Low, Z.,
Asadnia, M.,
Taheri kafrani, A.,
Razmjou, A. Biosensors and Bioelectronics (18734235)118pp. 66-79
Water pollution and habitat degradation are the cause of increasing water scarcity and decline in aquatic biodiversity. While the freshwater availability has been declining through past decades, water demand has continued to increase particularly in areas with arid and semi-arid climate. Monitoring of pollutants in wastewater effluents are critical to identifying water pollution area for treatment. Conventional detection methods are not effective in tracing multiple harmful components in wastewater due to their variability along different times and sources. Currently, the development of biosensing instruments attracted significant attention because of their high sensitivity, selectivity, reliability, simplicity, low-cost and real-time response. This paper provides a general overview on reported biosensors, which have been applied for the recognition of important organic chemicals, heavy metals, and microorganisms in dark waters. The significance and successes of nanotechnology in the field of biomolecular detection are also reviewed. The commercially available biosensors and their main challenges in wastewater monitoring are finally discussed. © 2018 Elsevier B.V.
Methods in Enzymology (00766879)609pp. 371-403
Enzymes are used as biocatalysts for analytical purposes in diagnostics and preparative purposes in large-scale industrial processes. Despite perfect catalytic properties of enzymes, their industrial applications are limited due to the drawbacks regarding the lack of long-term stability under process conditions. The difficulties associated with recycling have to be resolved before enzyme implementation at industrial scale. Enzyme immobilization, as a novel approach, can improve the half-life, stability, catalytic activity, and reusability of enzymes. Graphene-based nanomaterials, as nanoscaled and thermostable inorganic carriers, are nontoxic materials and selective modulators for enzyme activity. Herein, we have concentrated on strategies for preparing graphene-based nanocomposites for enzyme immobilization. Nanostructures of graphene, hybrid graphene, and their derivatives with adjustable surface chemistry, caused them to be excellent candidates for immobilization of enzymes. For instance, the synthesis and functionalization of Fe 3 O 4 –graphene oxide (GO) hybrids were improved recently, in our research group, using cyanuric chloride and polyethylene glycol bis-amine for the immobilization of xylanase and glucoamylase enzymes, via physical and covalent attachments. Decorating GO nanosheets with Fe 3 O 4 nanoparticles has facilitated the reusability of enzymes and increased the surface area for enzyme loading. The use of these hydrophilic crosslinkers may change the microenvironment of the immobilized enzymes that could result in the enhancement of their catalytic activity. As a result of the fascinating properties of graphene-based nanocarriers, with respect to structures that can be oriented and surfaces that can be modified, in our opinion, they offer some important advantages for biotechnological applications, especially in the areas of enzyme immobilization and medicine. © 2018 Elsevier Inc.
Journal of the Taiwan Institute of Chemical Engineers (18761070)93pp. 70-78
In this study, blood- and cardio-toxicity of Rh2–treated graphene oxide (GO-Rh2), lysine-treated graphene oxide (GO-Lys), arginine-treated GO (GO-Arg), Rh2–treated GO-Lys (GO-Lys-Rh2) and Rh2–treated GO-Arg (GO-Arg-Rh2) were evaluated. Two concentrations of each nanostructures (200 and 1000 µg/ml) was injected to rats. After 2 weeks, the effects of agents were evaluated on heart tissue by histopathological assays. Cytotoxicity of all designed nanostructures was investigated on blood cancer cells (K562) by MTT assay. Toxicity of designed nanostructures was also investigated on Red Blood Cells (RBCs), Prothrombin Time (PT) and Partial Thromboplastin Time (PTT). The results demonstrated increase of anticancer activity for GO-Arg-Rh2 and GO-Lys-Rh2 in comparison with free Rh2 and GO. GO, GO-Rh2, GO-Lys, GO-Arg, GO-Lys-Rh2, and GO-Arg-Rh2 had 50% hemolysis at concentrations 250, 360, 420, 435, 500, and 575 µg/ml, respectively. GO led to RBCs aggregation and morphological change at 5–100 µg/ml, but other functionalized nanostructures did not show these changes. All nanostructures had slight effect on intrinsic and extrinsic coagulation system, especially on PTT. GO-Arg-Rh2 and GO-Lys-Rh2 had lower effect on blood coagulation system in comparison with other examined nanosystems. Besides, GO-Rh2, GO-Arg-Rh2, and GO-Lys-Rh2 had lowest toxicity on heart tissue than other synthesized nanostructures. Functionalization of GO with Arg, Lys, and especially, Rh2 led to decrease the destruction of heart tissue. So, modified GO with Rh2 and basic amino acids may be a potential and promising strategy to enhance the therapeutic index for GO because of the reduction of side effects on normal cells. © 2018 Taiwan Institute of Chemical Engineers
Poorebrahim, M.,
Asghari, M.,
Abazari, M.F.,
Askari, H.,
Sadeghi, S.,
Taheri kafrani, A.,
Nasr-esfahani, M.H.,
Ghoraeian, P.,
Aleagha, M.N.,
Arab, S.S. Progress in Neuro-Psychopharmacology and Biological Psychiatry (18784216)82pp. 49-61
The efficiency of interferon beta (IFNβ)-based drugs is considerably limited due to their undesirable properties, especially high immunogenicity. In this study, for the first time we investigated the impact of a computationally designed peptide mimetic of IFNβ called MSPEP27, in the animal model of MS. A peptide library was constructed using the Rosetta program based on the predominant IFNAR1-binding site of IFNβ. Molecular docking studies were carried out using ClusPro and HADDOCK tools. The GROMACS package was subsequently used for molecular dynamics (MD) simulations. Validation of peptide-receptor interaction was carried out using intrinsic fluorescence measurements. To explore in silico findings further, experimental autoimmune encephalomyelitis (EAE) was induced by subcutaneous immunization of myelin oligodendrocyte glycoprotein (MOG35-55). Mice were then separated into distinct groups and intravenously received 10 or 20 mg kg− 1 of MSPEP27 or IFNβ. The inflammatory mediators were monitored by immunohistochemistry (IL17, CD11b, CD45), quantitative real-time PCR (MMP2, MMP9, TIMP-1) and enzyme-linked immunosorbent assay (IL1β TNFα) methods. Among the library of tolerated peptides, MSPEP27, a peptide with favorable physicochemical properties, was chosen for further experiments. This peptide was shown to significantly interact with IFNAR1 in a dose-dependent manner. Like IFNβ MSPEP27 could efficiently bind to IFNAR1 and form a stable peptide-receptor complex during 30 ns MD simulations. In vivo analyses revealed that MSPEP27 could lessen inflammation by modulating the levels of inflammatory mediators. According to our results, MSPEP27 peptide could efficiently bind to IFNAR1 and suppress neuroinflammation in vivo. We conclude that MSPEP27 has protective effects against MOG-induced EAE via reduction of immune dysfunction and inflammation. © 2017 Elsevier Inc.
International Journal of Biological Macromolecules (01418130)113pp. 354-360
Enzyme immobilized on magnetic nanoparticles (MNPs) can be used as efficient recoverable biocatalysts under strong magnetic responses. In the present work, α-amylase was immobilized onto naringin functionalized MNPs via ionic interactions. For this purpose, the MNPs were functionalized with naringin, as a biocompatible flavonoid. The morphology, structure, and properties of functionalized MNPs and the immobilization of α-amylase on synthesized nanocomposite were characterized through different analytical tools including TGA, VSM, FTIR, SEM-EDX and TEM. Furthermore, the optimum conditions of temperature, pH, reaction time and enzyme concentration for immobilization process were investigated. The results showed that the optimal conditions for immobilization of α-amylase onto synthesized nanocarrier occurred at pH 6.5 and 55 °C. The reusability experiments revealed high activity maintenance of immobilized α-amylase even after 10 reaction cycles. Moreover, the storage stability of immobilized enzyme improved via immobilization in comparison with free one and it maintained 60% of its initial activity after 6 weeks storage at 4 °C. The improvements in enzyme catalytic properties via immobilization made this nanobiocatalyst as a good candidate in bio-industrial applications. Furthermore, the synthesized nanocomposite would have the potential for practical applications in other and binary enzyme immobilization. © 2018 Elsevier B.V.
Kordesedehi, R.,
Taheri kafrani, A.,
Rabbani, M.,
Kazemi, R.,
Mutangadura, D.,
Haertlé, T. Journal of Biotechnology (01681656)276pp. 10-14
Milk is a perfect source of nutrients for neonates. When breast feeding cannot be done, an infant's alimentation is usually initiated to cow's milk, among the primary foods. It has been reported that about 2.5% of juveniles under the age of 3 years manifest allergic reactions to cow's milk proteins. Among the cow's milk proteins, casein fractions are considered as the strongest allergenic proteins. The proteolytic enzymes of lactic acid bacteria (LAB), during fermentation of dairy products, can break down milk proteins especially caseins and subsequently reduce the immune reactivity of allergenic proteins. In this research, raw bovine and camel milk samples were screened for cocci LAB strains and after isolation, their proteolytic activity against bovine milk caseins were evaluated by SDS-PAGE and RP-HPLC. The potential of cocci LAB strains on αS1-casein degradation and their potential to break down the principle allergenic epitopes of this protein was detected using indirect competitive ELISA. Molecular identification of the best proteolytic strain was fulfilled by 16S rDNA fragment sequencing with universal primers. The obtained results demonstrated that Enterococcus faecium isolated from raw camel milk samples was the most efficient isolate in hydrolyzing Na-caseinate and αS1-casein. Hydrolysated αS1-casein by Enterococcus faecium was also less recognized by IgE of bovine milk allergic patients’ sera in comparison with native αS1-casein. It has been proposed that Enterococcus faecium could be an efficient strain in allergenicity reduction of cow's milk proteins. So it could be an excellent candidate to be potentially used in dairy industries. © 2018 Elsevier B.V.
Scientific Reports (20452322)8(1)
In this study, Rh2-treated graphene oxide (GO-Rh2), lysine-treated highly porous graphene (Gr-Lys), arginine-treated Gr (Gr-Arg), Rh2-treated Gr-Lys (Gr-Lys-Rh2) and Rh2-treated Gr-Arg (Gr-Arg-Rh2) were synthesized. MTT assay was used for evaluation of cytotoxicity of samples on ovarian cancer (OVCAR3), breast cancer (MDA-MB), Human melanoma (A375) and human mesenchymal stem cells (MSCs) cell lines. The percentage of apoptotic cells was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay. The hemolysis and blood coagulation activity of nanostructures were performed. Interestingly, Gr-Arg, Gr-Lys, Gr-Arg-Rh2, and Gr-Lys-Rh2 were more active against cancer cell lines in comparison with their cytotoxic activity against normal cell lines (MSCs) with IC50 values higher than 100 μg/ml. The results of TUNEL assay indicates a significant increase in the rates of TUNEL positive cells by increasing the concentrations of nanomaterials. Results were also shown that aggregation and changes of RBCs morphology were occurred in the presence of GO, GO-Rh2, Gr-Arg, Gr-Lys, Gr-Arg-Rh2, and Gr-Lys-Rh2. Note that all the samples had effect on blood coagulation system, especially on PTT. All nanostrucure act as antitumor drug so that binding of drugs to a nostructures is irresolvable and the whole structure enter to the cell as a drug. © 2018 The Author(s).
International Journal of Biological Macromolecules (01418130)108pp. 263-271
The interaction between apo-human serum transferrin (Apo-hTf) and alprazolam was investigated using various spectroscopic techniques. The drug quenched the fluorescence intensity of Apo-hTf and the mechanism behind the quenching was static. The thermodynamic parameters (ΔG, ΔH, and ΔS) that obtained from tryptophan fluorescence study revealed that the interactions between alprazolam and Apo-hTf were spontaneous. Collectively, hydrophobic interactions and hydrogen bonding most likely played major roles in Apo-hTf/alprazolam interactions. Also, the absorption spectra of Apo-hTf increased in the presence of increasing concentration of alprazolam, reflecting Apo-hTf structural alteration after drug's binding. The CD results demonstrated that the Apo-hTf/alprazolam interaction does not affect the protein secondary and tertiary structure significantly until the molar ratios (alprazolam/Apo-hTf) of 10, but the conformational changes become visible at higher molar ratios. The DSC results suggested that alprazolam stabilized the Apo-hTf at alprazolam/Apo-hTf molar ratio of 20. Based on the achieved results, this potentially therapeutic agent can significantly bind to Apo-hTf which also further confirmed by molecular docking study. This study on the interaction of the drug with Apo-hTf should be helpful for understanding the transportation and distribution of drugs in vivo, as well as the action mechanism and dynamics of a drug at the molecular level. © 2017 Elsevier B.V.
Shokri, D.,
Rabbani, M.,
Mohkam, M.,
Fatemi, S.M.,
Ghasemi, Y.,
Taheri kafrani, A. Probiotics And Antimicrobial Proteins (18671306)10(1)pp. 34-42
The emergence of antibiotic-resistant and food-spoilage microorganisms has renewed efforts to identify safe and natural alternative agents of antibiotics such as probiotics. The aim of this study was the isolation of lactobacilli as potential probiotics from local dairy products with broad antibacterial and anti-biofilm activities against antibiotic-resistant strains of Pseudomonas aeruginosa and determination of their inhibition mechanism. Antibiotic susceptibility and classification of acquired resistance profiles of 80 P. aeruginosa strains were determined based on Centers for Disease Control and Prevention (CDC) new definition as multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan-drug-resistant (PDR) followed by antibacterial assessment of lactobacilli against them by different methods. Among the 80 P. aeruginosa strains, 1 (1.3%), 50 (62.5%), and 78 (97.5%) were PDR, XDR, and MDR, respectively, and effective antibiotics against them were fosfomycin and polymyxins. Among 57 isolated lactobacillus strains, two strains which were identified as Lactobacillus fermentum using biochemical and 16S rDNA methods showed broad inhibition/killing and anti-biofilm effects against all P. aeruginosa strains. They formed strong biofilms and had bile salts and low pH tolerance. Although investigation of inhibition mechanism of these strains showed no bacteriocin production, results obtained by high-performance liquid chromatography (HPLC) analysis indicated that their inhibitory effect was the result of production of three main organic acids including lactic acid, acetic acid, and formic acid. Considering the broad activity of these two L. fermentum strains, they can potentially be used in bio-control of drug-resistant strains of P. aeruginosa. © 2017, Springer Science+Business Media New York.
International Journal of Biological Macromolecules (01418130)107(PartA)pp. 418-425
In order to utilize the advantages of immobilization such as improvement of stability, increasing the catalytic activity, ability to recovery and reuse of enzyme from reaction medium, xylanase enzyme was immobilized on superparamagnetic garphene oxide nanosheets (GOMNP). Xylanase, as a hydrolytic enzyme of xylan has widely used in industry. Since the xylan is bulk, for enhance accessibility of active sites of the immobilized xylanase, polyethylene glycol bis amine (PEGA) was used as a spacer for functionalization of GOMNP. The modified GOMNP and immobilized xylanase on PEGA-GOMNP (PEGA-GOMNP/Xy) were characterized through different analysis tools. The results showed that xylanase was attached to the functionalized nanocomposite with a yield of 273 mg enzyme per gram PEGA-GOMNP. Thermal stability, pH stability, reusability and storage stability were determined for immobilized enzyme. The free and immobilized xylanase displayed an optimal enzymatic activity at 60 °C and pH 6.5 and 7.5, respectively. The immobilized enzyme retained about 40% of the initial activity after 8 cycles with xylan substrate at 60 °C. Also immobilized and free enzymes retained 35% and 20% of the initial catalytic activity after 90 days storage at 4 °C, respectively. Consequently, PEGA- modified GOMNP can be introduced as a biodegradable and suitable support for bioengineering. © 2017 Elsevier B.V.
Nazari, R.,
Aghababaie, M.,
Razmjou, A.,
Landrani, A.,
Amini, M.,
Hajjari, M.,
Mirkhani, V.,
Moghadam, M.,
Taheri kafrani, A. Desalination and Water Treatment (19443994)64pp. 81-89
Forward osmosis (FO) has gained attention recently due to its low cost and energy consumption while it happens naturally. However, finding a proper draw agent for this process is a challenging task. Magnetic nanoparticles, especially with modified surfaces, have been reported as a promising draw agent, which can be easily recovered by using a magnetic field. Here, an attempt was made to study the effect of different superparamagnetic iron oxide nanoparticles (SPIONs) surface engineering on the osmotic pressure, hydrophilicity, degree of agglomeration of nanoparticles and also water flux. In this study, the osmotic potential of naked Fe3O4, silica-coated superparamagnetic iron oxide nanoparticles (SPION@SiO2), hyperbranched polyglycerol/carboxylate-functionalized SPION (SPION@SiO2@ HPG and SPION@SiO2@HPG-CO2H) were evaluated for FO process. The effect of ionized SPIONs on the water flux has been studied for the first time, too. The SPIONs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared, vibrating sample magnetometer and thermogravimetric analysis. The average of water flux in a long-term performance of FO for the introduced draw agents increased in the order of SPION < SPION@SiO2 < SPION@SiO2@HPG < SPION@SiO2@HPG-CO2H due to higher hydrophilicity and lesser agglomerations and precipitation. It was surprisingly observed that water flux of ionic magnetic draw solution behaves differently comparing with the non-ionic ones. It was revealed that ionic SPIONs at high concentration led to the formation of non-ideal polyelectrolyte solution that produces a high osmotic pressure. However, by the permeation of water, a transition from non-ideal to ideal solution at some point was observed during FO process. © 2017 Desalination Publications. All rights reserved.
Biochemical Engineering Journal (1369703X)127pp. 119-127
Aspergillus niger glucoamylase (GLA) was covalently immobilized on 1,3,5-triazine-functionalized chitosan coated superparamagnetic nanoparticles (MNPCh-CC). The morphology, structure and properties of functionalized nanocomposite were investigated, as well as GLA immobilization process, through different analytical tools. Different experimental parameters such as optimum temperature, pH, reaction time and enzyme concentration were studied for free and immobilized enzyme. The GLA immobilized on nanocarrier exhibited excellent catalytic activity at pH 4.5 and 60 °C. Notably, the immobilized GLA showed quite impressive stability, even after 10 reaction cycles, it could still retain about 70% of the initial activity. The results showed that immobilization process couldn't significantly inhibit enzyme-substrate interaction and subsequently retained its effective catalytic activity. The substantial improvement of reactivity, reusability, and stability of this biocatalyst system may confer it a wider range of applications in industrial processes. © 2017 Elsevier B.V.
Shokri, D.,
Rabbani, M.,
Zaghian, S.,
Fatemi, S.M.,
Mohkam, M.,
Ghasemi, Y.,
Taheri kafrani, A. Jundishapur Journal Of Microbiology (20083645)9(8)
Background: The emergence of pan-drug resistant strains (PDR) of Pseudomonas aeruginosa has led to renewed efforts to identify alternative agents, such as bacteriocins and bacteriocin-like inhibitory substances (BLISs). Objectives: The aims of this study were to determine the acquired resistance profiles of multidrug-resistant (MDR), extensively drug-resistant (XDR), and PDR P. aeruginosa isolates based on the revised definitions of the CDC and ECDC and to screen and characterize effective BLISs against these isolates. Patients and Materials: In a cross-sectional study, 96 P. aeruginosa strains were isolated during a 12-month period. The resistance profiles of these isolates were determined as MDR, XDR, and PDR, and the data were analyzed using WHONET5.6 software. A BLIS against the P. aeruginosa strains was characterized based on its physicochemical properties, size, growth curves, and production profiles. Results: Among the 96 isolates of P. aeruginosa, 2 (2.1%), 94 (97.9%), and 63 (65.6%) were non-MDR, MDR, and XDR, respectively, and 1 (1.1%) was PDR. The most effective antibiotics against these isolates were polymyxins and fosfomycin. A BLIS isolated from the P. aeruginosa DSH22 strain had potent activity against 92 (95.8%) of the 96 isolates. The BLIS was heat stable, (up to 100°C for 10 min), UV stable, and active within a pH range of 3 - 9. The activity of BLIS disappeared when treated with trypsin, proteinase K, and pepsin, indicating its proteinous nature. Based on its size (25 kDa), the BLIS may belong to the large colicin-like bacteriocin family. BLIS production started in the midexponential phase of growth, and the maximum level (2700 AU/mL) occurred in the late-stationary phase after 25 hours of incubation at 30°C. Conclusions: This BLIS with broad-spectrum activity may be a potential agent for the treatment or control of drug-resistant strains of P. aeruginosa infection. © 2016. Ahvaz Jundishapur University of Medical Sciences.
Biochemical Engineering Journal (1369703X)109pp. 51-58
1,3,5-Triazine-functionalized silica encapsulated magnetic nanoparticles (MNPs) have been successfully synthesized. The morphology, structure and properties of functionalized nanoparticles were investigated through different analytical tools including Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray powder diffraction. Due to the magnetic nature and the presence of triazine functionalized groups, the as-prepared Fe3O4@SiO2 nanoparticles were employed as magnetic carriers for xylanase immobilization. The xylanase immobilized on functionalized MNPs (Xy-MNP) exhibited excellent catalytic activity at pH 6.5 and 65°C. Notably, Xy-MNPs had significant effect on juice clarity and showed quite impressive stability, even after 10 reaction cycles in the enrichment of the juices clarification, it could still retain about 55% of the initial activity. The Xy-MNPs illustrated similar clarity enrichment for three types of fruit juices, after 5h incubation at 50°C. The effect of metal ions and organic solvents on the activity of immobilized xylanase was investigated. The results showed an increasing in the catalytic activity of Xy-MNPs in the presence of some metal ions while they have inhibitory effect on the activity of free xylanase. Also both free and immobilized xylanase were inhibited in the presence of 50% (v/v) organic solvents, whereas the Xy-MNPs activity was significantly increased in the presence of 10% (v/v) organic solvents. It is hoped that the 1,3,5-triazine-functionalized Fe3O4@SiO2 nanoparticles may find an application in modern biotechnology. © 2016 Elsevier B.V.
Chemical Engineering Journal (13858947)288pp. 414-422
Immobilized enzymes are used as biocatalysts for analytical purposes in diagnostics and for preparative purposes in large scale industrial processes. Immobilization can increase the half-life, improve the stability, and increase the catalytic activity of an enzyme. It facilitates the separation and recovery of the catalyst from the reaction products, and allows for multiple use of the biocatalysts. Graphene oxide nanosheets were decorated with superparamagnetic iron oxide nanoparticles (SPGO) and functionalized with cyanuric chloride (SPGO-CC) to serve as solid support for the covalent immobilization of enzymes. Xylanase was attached to the functionalized nanocomposite with a yield of 215 mg protein pergram SPGO-CC. The kinetic constants of the immobilized (of the free soluble) xylanase are Km=4.9 (4.1) mg/mL, vmax=1.6 (1.7)μmol min-1 mL-1, and kcat=82 (91) min-1, indicating a minimal impairment of catalytic activity by covalent coupling. The immobilized xylanase has shallow pH and temperature optima of 6.5 and 60°C. It retains 70% of the original activity after 10 cycles of 15min incubation with substrate (polymeric xylan) at 60°C. It retains 80% of the original catalytic activity after 3.5months storage at 4°C, whereas the free, soluble enzyme retains only 50%. © 2015 Elsevier B.V.
International Journal of Biological Macromolecules (01418130)93pp. 1183-1191
Immobilization of an enzyme can enhance its catalytic activity, depending on the properties of the enzyme and the matrix. Graphene oxide is a nontoxic material and selective modulator for enzyme activity and is also a thermostable molecule that is important in large-scale nanostructure sheet applications. Herein, we have successfully developed a strategy for preparing a nanocomposite for enzyme immobilization model with high loading capacity. Nanostructures of hybrid graphene oxide-Fe3O4-cyanuric chloride (GO/MNP-CC) have adjustable surface chemistry that is an excellent candidate for covalent immobilization of enzymes. The morphology, structure and properties of GO/MNP-CC nanocomposite were investigated through different analytical tools. Glucoamylase, an important enzyme in industrial food products, was immobilized on GO/MNP-CC and exhibited excellent catalytic activity at pH 6.5 and 60 °C. The results of this study indicated that the catalytic activity, reusability and stability of immobilized enzyme have been obviously improved compared to the free enzyme. The apparent Km and νmax for free and immobilized glucoamylase were also determined. These properties make them a good candidate to improve the practicality and further the development of the capacity enzyme attachment. Thus, the synthesized matrix has the potential for practical applications in other and binary enzyme immobilization and would have a wide prospect for their applications in bio-industry and biosensing. © 2016 Elsevier B.V.
Yousefi, R.,
Jamshidi, M.,
Shahsavani, M.B.,
Nabavizadeh, S.M.,
Haghighi, M.G.,
Rashidi, M.,
Taheri kafrani, A.,
Niazi, A.,
Keshavarz, F.,
Alavinamehr, M.M. Journal Of The Iranian Chemical Society (1735207X)13(4)pp. 617-630
Human serum albumin (HSA) primarily functions as a transport carrier for a vast variety of natural ligands and pharmaceutical drugs. In the present study, three structurally related cationic Pt(II) complexes ([Pt(ppy)(dppe)]CF3CO2: 1, Pt(bhq)(dppe)]CF3CO2: 2, and [Pt(bhq)(dppf)]CF3CO2: 3) were used to evaluate their interaction with HSA under different experimental setups, using UV-Vis absorption spectroscopy, fluorescence and circular dichroism techniques. The spectroscopic results suggest that upon binding to HSA, the Pt(II) complexes could effectively induce structural alteration of the protein. The complexes can bind to HSA with the binding affinities of the following order: 3 > 2 > 1. Also, thermodynamic parameters of binding between these complexes and HSA indicated the existence of entropy-driven spontaneous interaction which primarily dominated with the hydrophobic forces. Also, docking simulation study revealed the binding details of these complexes on HSA. Complex 3 with highest binding affinity for HSA indicates lowest denaturing effect on this protein. The low denaturation properties of 3 appear important in the terms of lower susceptibility of this platinum complex for possible development of deleterious side effects. © 2015 Iranian Chemical Society.
Chemical Engineering Journal (13858947)270pp. 235-243
The covalent binding of xylanase to silica-coated modified magnetite nanoparticles via cyanuric chloride activation was investigated. The structure, size, and magnetic properties of the support and immobilized xylanase were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectra (FTIR), thermo-gravimetric analysis (TGA) and vibrating sample magnetometer (VSM) analysis. The TEM images showed that the xylanase immobilized on functionalized magnetic nanoparticles (xylanase-MNPs) possessed three dimensional core-shell structures with an average diameter of ~9nm. The FTIR and XPS results demonstrated the successful immobilization of xylanase on functionalized MNPs. Results from Bradford protein assay and TGA indicated that xylanase was covalently attached to the surface of modified magnetic nanoparticles with immobilization yield of 280mg enzyme/gMNPs. The VSM analysis revealed that Fe3O4, Fe3O4@SiO2 and xylanase-MNPs had high saturation magnetization of 69.4, 63.84 and 46.56emu/g, respectively. Enzymatic activity, reusability, thermo-stability, pH-stability, and storage stability of the immobilized xylanase were found significantly superior to those of the free one. The xylanase-MNPs exhibited maximal catalytic activity at pH 6.5 and 60°C and the immobilized enzymes were found to keep as high as 80% of the activity of free ones. Notably, xylanase-MNPs showed quite impressive stability, even after 9 reaction cycles, it could still retain about 65% of the initial activity. The measurement of Michaelis-Menten parameters (Km and vmax) also revealed the considerable improvement of immobilized enzyme. The results suggested that xylanase-MNPs could be used in an interesting range of application allowing both using in broader temperature and pH ranges, facilitating long-term storage, while permitting magnetic recovery of the enzyme for reuse or purification of the product. © 2015 Elsevier B.V.
Zare-zardini, H.,
Taheri kafrani, A.,
Ordooei, M.,
Ebrahimi, L.,
Tolueinia, B.,
Soleimanizadeh, M. Biochemistry (Moscow) (00062979)80(4)pp. 433-440
Antimicrobial peptides are members of the immune system that protect the host from infection. In this study, a potent and structurally novel antimicrobial peptide was isolated and characterized from praying mantis Sphodromantis viridis. This 14-amino acid peptide was purified by RP-HPLC. Tandem mass spectrometry was used for sequencing this peptide, and the results showed that the peptide belongs to the Mastoparan family. The peptide was named Mastoparan-S. Mastoparan-S demonstrated that it has antimicrobial activities against a broad spectrum of microorganisms (Gram-positive and Gram-negative bacteria and fungi), and it was found to be more potent than common antibiotics such as kanamycin. Mastoparan-S showed higher antimicrobial activity against Gram-negative bacteria compared to Gram-positive ones and fungi. The minimum inhibitory concentration (MIC) values of Mastoparan-S are 15.1-28.3 μg/ml for bacterial and 19.3-24.6 μg/ml for fungal pathogens. In addition, this newly described peptide showed low hemolytic activity against human red blood cells. The in vitro cytotoxicity of Mastoparan-S was also evaluated on monolayer of normal human cells (HeLa) by MTT assay, and the results illustrated that Mastoparan-S had significant cytotoxicity at concentrations higher than 40 μg/ml and had no any cytotoxicity at the MIC (≤30 μg/ml). The findings of the present study reveal that this newly described peptide can be introduced as an appropriate candidate for treatment of topical infection. © 2015 Pleiades Publishing, Ltd.
Zare-zardini, H.,
Amiri, A.,
Shanbedi, M.,
Taheri kafrani, A.,
Kazi, S.N.,
Chew, B.T.,
Razmjou, A. Journal of Biomedical Materials Research - Part A (15493296)103(9)pp. 2959-2965
One of the novel applications of the nanostructures is the modification and development of membranes for hemocompatibility of hemodialysis. The toxicity and hemocompatibility of Ag nanoparticles and arginine-treated multiwalled carbon nanotubes (MWNT-Arg) and possibility of their application in membrane technology are investigated here. MWNT-Arg is prepared by amidation reactions, followed by characterization by FTIR spectroscopy, Raman spectroscopy, and thermogravimetric analysis. The results showed a good hemocompatibility and the hemolytic rates in the presence of both MWNT-Arg and Ag nanoparticles. The hemolytic rate of Ag nanoparticles was lower than that of MWNT-Arg. In vivo study revealed that Ag nanoparticle and MWNT-Arg decreased Hematocrit and mean number of red blood cells (RBC) statistically at concentration of 100 μg mL-1. The mean decrease of RBC and Hematocrit for Ag nanoparticles (18% for Hematocrit and 5.8 × 1,000,000/μL) was more than MWNT-Arg (20% for Hematocrit and 6 × 1000000/μL). In addition, MWNT-Arg and Ag nanoparticles had a direct influence on the White Blood Cell (WBC) drop. Regarding both nanostructures, although the number of WBC increased in initial concentration, it decreased significantly at the concentration of 100 μg mL-1. It is worth mentioning that the toxicity of Ag nanoparticle on WBC was higher than that of MWNT-Arg. Because of potent antimicrobial activity and relative hemocompatibility, MWNT-Arg could be considered as a new candidate for biomedical applications in the future especially for hemodialysis membranes. © 2015 Wiley Periodicals, Inc.
Yousefi, R.,
Mohammadi, R.,
Taheri kafrani, A.,
Shahsavani, M.B.,
Dadkhah aseman, M.,
Nabavizadeh, S.M.,
Rashidi, M.,
Poursasan, N.,
Moosavi-movahedi, A. Journal of Luminescence (00222313)159pp. 139-146
This study describes HSA binding properties of two cyclometalated platinum (II) complexes with non-leaving lipophilic ligands; deprotonated 2-phenylpyridine (ppy): C1 and deprotonated benzo [h]quinolone (bhq): C2, using UV-vis, fluorescence and circular dichroism (CD) spectroscopy. The absorption spectra of HSA decreased in the presence of increasing concentration of these complexes, reflecting HSA structural alteration after drug's binding. Also the thermodynamic parameters (ΔG, ΔH and ΔS) that obtained from Trp fluorescence study revealed that the interaction between these complexes and HSA were spontaneous. In addition, C1 with flexible chemical structure indicated significantly higher fluorescence quenching and binding affinity to HSA than C2 which possesses a higher structural rigidity. The ANS fluorescence results also indicated that two Pt (II) complexes were competing for binding to the hydrophobic regions of HSA. Moreover, CD results demonstrated that C2 complex induced alteration of HSA conformation to more significant extent compared to C1. The molecular docking results revealed the involvement of π-π stacking and hydrophobic interaction between these complexes and the protein. Overall, this study may highlight the significance of structural flexibility in designing of future anticancer Pt (II) complexes with improved binding affinity for HSA. © 2014 Elsevier B.V. All rights reserved.
International Journal of Biological Macromolecules (01418130)
β-Lactoglobulin (β-LG) is a member of lipocalin superfamily of transporters for small hydrophobic molecules. β-LG is also one of the major allergens in milk. Despite a lot of researches on decreasing of cow's milk allergenicity, the effects of the mutation of β-LG on its recognition by IgE from cow's milk allergy (CMA) patients have not been investigated. We described here the expression in the yeast Pichia pastoris of a mutant β-LG, in which Alanine86 was changed into Glutamine (Ala86Gln; a mutation on one of the major epitopes of the protein). The purity and native like folded structure of the recombinant Ala86Gln have been demonstrated using circular dichroism, HPLC, SDS-PAGE and mass spectrometry. The effect of the mutation on the binding of IgE from CMA patients to mutant protein was evaluated by ELISA methods and the results showed that the mutation of Ala86 was associated with weaker binding of IgE from CMA patients to Ala86Gln mutant protein. Subsequently, the binding of various ligands such as retinol, palmitic acid, resveratrol and serotonin, with native, recombinant wild type and Ala86Gln mutant β-LGs were investigated by fluorescence spectroscopy and an improvement on the binding affinity of the mutated protein to various ligands was observed. © 2015. Published by Elsevier B.V.
Landrani, A.,
Taheri kafrani, A.,
Amini, M.,
Mirkhani, V.,
Moghadam, M.,
Soozanipour, A.,
Razmjou, A. Langmuir (15205827)31(33)pp. 9219-9227
Although several strategies are now available for immobilization of enzymes to magnetic nanoparticles for bioapplications, little progresses have been reported on the use of dendritic or hyperbranched polymers for the same purpose. Herein, we demonstrated synthesis of magnetic nanoparticles supported hyperbranched polyglycerol (MNP/HPG) and a derivative conjugated with citric acid (MNP/HPG-CA) as unique and convenient nanoplatforms for immobilization of enzymes. Then, an important industrial enzyme, xylanase, was immobilized on the nanocarriers to produce robust biocatalysts. A variety of analytical tools were used to study the morphological, structural, and chemical properties of the biocatalysts. Additionally, the results of biocatalyst systems exhibited the substantial improvement of reactivity, reusability, and stability of xylanase due to this strategy, which might confer them a wider range of applications. © 2015 American Chemical Society.
Journal of Biotechnology (01681656)212pp. 181-188
β-Lactoglobulin (β-LG) is a member of lipocalin superfamily of transporters for small hydrophobic molecules such as retinoids, fatty acids, drugs, and vitamins. β-LG also is one of the major allergens in milk. Despite a lot of research on decreasing cow's milk allergenicity, the effects of mutations of β-LG on recognition by IgE from cow's milk allergy (CMA) patients have not been investigated. We describe here the expression in the yeast Pichia pastoris of a mutant bovine β-LG, in which lysine at position 69, in the main epitopes of the protein, was changed into asparagine (Lys69Asn). The purity and native like folded structure of the recombinant Lys69Asn β-LG was confirmed by HPLC, SDS-PAGE, mass spectrometry and circular dichroism. Lys69Asn β-LG has a fourfold stronger affinity than the wild-type protein for retinol, palmitic acid, and resveratrol, as determined by quenching of the intrinsic tryptophan fluorescence. At the same time the Lys69Asn mutant had a 9 fold attenuated, compared with the wild-type, affinity for IgE of sera from patients suffering from cow's milk allergy, whereas no difference could be detected between mutant and wild-type for binding of the IgGs of four monoclonal antibodies. The results of this study demonstrated the significant role of Lys69 residue on the binding and immuoreactivity properties of β-LG. © 2015 Elsevier B.V..
International Journal of Biological Macromolecules (01418130)81pp. 340-348
beta-Lactoglobulin (beta-LG) is a member of lipocalin superfamily of transporters for small hydrophobic molecules. beta-LG is also one of the major allergens in milk. Despite a lot of researches on decreasing of cow's milk allergenicity, the effects of the mutation of beta-LG on its recognition by IgE from cow's milk allergy (CMA) patients have not been investigated. We described here the expression in the yeast Pichia pastoris of a mutant beta-LG, in which Alanine 86 was changed into Glutamine (Ala86Gln; a mutation on one of the major epitopes of the protein). The purity and native like folded structure of the recombinant Ala86GIn have been demonstrated using circular dichroism, HPLC, SDS-PAGE and mass spectrometry. The effect of the mutation on the binding of IgE from CMA patients to mutant protein was evaluated by ELISA methods and the results showed that the mutation of Ala-86 was associated with weaker binding of IgE from CMA patients to Ala86GIn mutant protein. Subsequently, the binding of various ligands such as retinol, palmitic acid, resveratrol and serotonin, with native, recombinant wild type and Ala86GIn mutant beta-LGs were investigated by fluorescence spectroscopy and an improvement on the binding affinity of the mutated protein to various ligands was observed. (C) 2015 Elsevier B.V. All rights reserved.
Journal Of Thermal Analysis And Calorimetry (13886150)115(3)pp. 2123-2127
Isothermal titration calorimetry (ITC) was utilized at conditions close to physiologic (50 mM HEPES buffer, pH 7.4 and 160 mM NaCl) and at various temperatures (20, 25, 30, 35, and 40 C) to evaluate the enthalpy and heat capacity changes for the interactions of sodium n-dodecyl sulfate (SDS) as an anionic surfactant with apo-human transferrin (apo-hTf). The obtained results are very informative due to importance of heat capacity change as a major thermodynamic quantity that is one of the richest potential sources of information in physical terms. The obtained precise curves and heat capacity curves were interpreted in terms of molecular events such as specific and non-specific binding and the unfolding process. A three step mechanism for the interaction of SDS with apo-hTf has been figured out on basis of ITC studies: N ↔ I1 ↔ I2 ↔ D, where N, I, and D correspond to native, partially unfolded, and denatured states, respectively. © 2013 Akadémiai Kiadó, Budapest, Hungary.
Acta Chimica Slovenica (13180207)61(3)pp. 645-649
Isothermal titration calorimetry (ITC) was utilized at conditions close to physiological (50 mM HEPES buffer, pH 7.4 and 160 mM NaCl) and at various temperatures of 25, 30, 35 and 40 °C to evaluate the thermodynamic parameters, enthalpy and heat capacity changes, and subsequently the unfolding process of apo-human serum tarnsferrin (apo-hTf) in the presence of cetylpyridinium chloride (CPC) as a cationic surfactant. The precise thermograms and heat capacity curves obtained and interpreted in terms of molecular events such as specific and non-specific binding and the unfolding process. The analysis of obtained enthalpograms and heat capacity changes profile showed a distinct extreme region close to [CPC]/[apo-hTf] mole ratio of 20 indicated that predominant cooperative unfolding occurs at this mole ratio via a two states mechanism. © 2014 Acta Chim. Slov.
Colloids and Surfaces B: Biointerfaces (18734367)112pp. 374-379
Bovine milk β-lactoglobulin (β-LG) demonstrates significant resistance against both gastric- and simulated duodenal digestions. Therefore, it seems a realistic protein candidate for safe delivery and protection of particularly pH sensitive drugs in stomach. Recently, pyrimidine fused heterocycles (PFHs) revealed inhibitory properties against α-glucosidase (α-Gls) which is an important target enzyme for those drugs playing significant role in treatment of type-II diabetes and HIV/AIDS infection. The delivery of these compounds to small intestine where the enzyme plays its biological function is of great importance. Therefore, in this work the interaction of PFH compounds with β-LG, as a carrier protein has been investigated. Fluorescence, circular dichroism (CD) and UV-vis spectroscopic studies were used to examine the binding parameters and binding modes of the interaction. Moreover, the effects of PFH complexation on the secondary structures of β-LG were studied. All of these compounds significantly quenched the fluorescence intensity of β-LG due to a ground state complex formation. The binding and thermodynamic parameters were calculated. While hydrophobic interactions were proved to play significant role in the interaction of L1, L2 and L3, hydrogen bonding was shown to be important in the complexation of L4. The secondary structures of β-LG were preserved upon interaction of these synthetic compounds. Based on the achieved results, these potentially therapeutic agents can significantly bind to β-LG. Consequently, this protein might be useful for delivery of PFH compounds to small intestine where representing their potential ability to inhibit α-Gls and to reduce the postprandial hyperglycemia in diabetic patients. © 2013 Elsevier B.V.
Taheri kafrani, A.,
Choiset, Y.,
Faizullin, D.A.,
Zuev, Y.F.,
Bezuglov, V.V.,
Chobert, J.,
Bordbar, A.,
Haertlé, T. Biopolymers (10970282)95(12)pp. 871-880
β-Lactoglobulin (β-LG) is a lipocalin, which is the major whey protein of cow's milk and the milk of other mammals. However, it is absent from human milk. The biological function of β-LG is not clear, but its potential role in carrying fatty acids through the digestive tract has been suggested. β-LG has been found in complexes with lipids such as butyric and oleic acids and has a high affinity for a wide variety of compounds. Serotonin (5-hydroxytryptamine, 5-HT), an important compound found in animals and plants, has various functions, including the regulation of mood, appetite, sleep, muscle contraction, and some cognitive functions such as memory and learning. In this study, the interaction of serotonin and one of its derivatives, arachidonyl serotonin (AA-5HT), with β-LG was investigated using circular dichroism (CD) and fluorescence intensity measurements. These two ligands interact with β-LG forming equimolar complexes. The binding constant for the serotonin/β-LG interaction is between 10 5 and 10 6 M -1, whereas for the AA-5HT/β-LG complex it is between 10 4 and 10 5 M -1 as determined by measurements of either protein or ligand fluorescence. The observed binding affinities were higher in hydroethanolic media (25% EtOH). The interactions between serotonin/β-LG and AA-5HT/β-LG may compete with self-association (micellization) of both the ligand and the protein. According to far- and near-UV CD results, these ligands have no apparent influence on β-LG secondary structure, however they partially destabilize its tertiary structure. Their binding by β-LG may be one of the peripheral mechanisms of the regulation of the content of serotonin and its derivatives in the bowel of milk-fed animals. © 2011 Wiley Periodicals, Inc.
Colloids and Surfaces B: Biointerfaces (09277765)75(1)pp. 268-274
Bovine β-lactoglobulin (β-LG) present in milks has been found "in vivo" in complexes with lipids such as butyric and oleic acids. To elucidate the still unknown structure-function relationship in this protein, the structural changes of β-lactoglobulin variant A (β-LG A) in the presence of cationic surfactant such as dodecyltrimethyl ammonium bromide (DTAB) have been investigated using various experimental techniques such as UV-vis spectrophotometry, fluorimetry, isothermal titration calorimetry (ITC) and circular dichroism (CD). Subsequently, the retinol binding by β-LG has been investigated in the presence of various amounts of this surfactant as its extrinsic functional binding fluorophore. Comparison of the results allowed to determine the binding of retinol by β-LG in the presence of DTAB. The results of UV-vis and fluorescence studies showed a red shift in wavelength and an increase in absorbance and enhancement in the intensity of the quantum yield of protein during its interaction with DTAB. The results of UV-vis also showed two distinct conformational changes corresponding first to precipitation and second to solubilization of the precipitated β-LG at pH 6.7 and 8.0. The results indicate the cooperative character of binding at pH 2.0. The results of fluorescence studies showed that the binding strength of β-LG/DTAB complex increases with the increase of the pH. CD results showed the shifts in positions of the major minima and change in magnitude of ellipticity and subsequently signified two significant changes in structure of β-LG between 10-30 and 50-100 molar ratio of [DTAB]/[β-LG]. ITC measurements indicated the endothermic nature of β-LG/DTAB interactions at pH 6.7 and the exothermic nature of β-LG/DTAB interactions at pH 8.0. The analysis of the binding data demonstrates the absence of significant changes in retinol-binding properties of β-LG in the presence of various amounts of this surfactant. This implies that surfactant binding does not change the conformation of β-LG in the regions defining retinol-binding site nor interferes with retinol binding by a competition for the same binding site(s). © 2009 Elsevier B.V. All rights reserved.
Taheri kafrani, A.,
Gaudin, J.,
Rabesona, H.,
Nioi, C.,
Agarwal, D.,
Drouet, M.,
Chobert, J.,
Bordbar, A.,
Haertlé, T. Journal of Agricultural and Food Chemistry (00218561)57(11)pp. 4974-4982
β-Lactoglobulin (β-LG) is one of the cow's major milk proteins and the most abundant whey protein. This globular protein of about 18 kDa is folded, forming a β-barrel (or calyx) structure. This structure Is stabilized by two disulflde bonds and can be altered by heating above 65 °C. β-LG Is also one of the major allergens In milk. Heating Is one of the most common technologic treatments applied during many milk transformations. During heating in the presence of reducing sugars, β-LG Is also submitted to the Maillard reaction, which at the first stage consists of the covalent fixation of sugars on the e-amino groups of lysyl residues. The following steps are condensation and polymerization reactions leading to the formation of melanoidins (brown pigments). Despite the frequency of use of heating during milk transformation, the effects of heat-induced denaturation and of glycation of β-LG on its recognition by IgE from cow's milk allergy (CMA) patients are not fully understood. The objectives of our work were to evaluate the effect of heat-induced denaturation of bovine β-LG on binding of IgE from CMA patients and to determine the effect of moderate glycation on the degree of recognition by IgE. We showed that heat-induced denaturation (loss of tertiary and secondary structures) of β-LG is associated with weaker binding of IgE from CMA patients. It was also shown that moderate glycation of β-LG In early stages of Maillard reaction has only a small effect on Its recognition by IgE, whereas a high degree of glycation has a clear "masking" effect on the recognition of epitopes. This demonstrates the importance of e-amino groups of lysines in the definition of epitopes recognized by IgE. © 2009 American Chemical Society.
Journal Of Thermal Analysis And Calorimetry (13886150)98(2)pp. 567-575
The micellization characteristics of sodium n-dodecyl sulfate (SDS) have been investigated by microcalorimetric technique at conditions close to the physiological ones. The thermodynamics of micellization were studied at 20, 25, 30, 35 and 40 °C in 50 mM HEPES buffer, pH 7.4 and 160 mM NaCl using isothermal titration calorimetric (ITC) technique. The calorimeter can operate in a stepwise addition mode, providing an excellent method of determination of critical micelle concentration (CMC) and enthalpy of demicellization (and hence micellization). It can as well distinguish between aggregating and non-aggregating amphiphiles (solutes) in solution. The dilution enthalpy (ΔH dil) was calculated and graphed versus concentration in order to determine the micellization enthalpy (ΔH mic) and CMC. In addition to the CMC and ΔH mic, the effective micellar charge fraction (α) of the ionic surfactant micellization process can also be determined from ITC curves. The Gibbs free energy of the micellization (ΔG mic), entropy of the micellization (ΔS mic), and specific heat capacity of the micellization (ΔC P,mic) process have been evaluated by the direct calorimetric method (mass-action model) as well as by the indirect method of van't Hoff by processing the CMC and α results of microcalorimetry at different temperatures. The differences of the results obtained by these two procedures have been discussed. The presence of NaCl (160 mM) in the solutions decreased the CMC of SDS. The enthalpy changes associated with micelle dissociation were temperature-dependent, indicating the importance of hydrophobic interactions. The ΔG mic was found to be negative, implying, as expected, that micellization occurs spontaneously once the CMC has been reached. The values of ΔG mic were found to become more negative with increasing temperature and the ΔS mic was found to decrease with increasing temperature in both models. © 2009 Akadémiai Kiadó, Budapest, Hungary.
Colloids and Surfaces B: Biointerfaces (09277765)73(1)pp. 132-139
The interaction of cationic surfactants, n-alkyl trimethyl ammonium bromides (CnTAB, n = 12 and 14), with cellulase from Aspergillus niger has been investigated at 25 °C and various pH, using CnTAB-membrane selective electrodes as a simple, fast, cheap and accurate technique and fluorescence spectroscopy. The regions of C1 (the surfactant concentration at which binding is initiated) and C2 (enzyme saturated by surfactant) were determined using potentiometric measurements. The obtained binding isotherms have been analyzed using Scatchard plot and binding capacity concept. The results were interpreted on the basis of nature of forces which interfered in the interaction and represent two binding sets system for all of the studied conditions. Hill equation parameters have been estimated and used for calculation of intrinsic Gibbs free energy that decreases with extension of binding. The effect of CnTAB binding on cellulase intrinsic fluorescence spectra was also examined. A biphasic behavior was observed for quenching process of endoglucanase by CnTAB that confirms the results of binding studies correspond to the existence of two types of binding sites for CnTAB on cellulase. © 2009 Elsevier B.V. All rights reserved.
Archives of Biochemistry and Biophysics (10960384)470(2)pp. 103-110
The heat capacity changes for interaction of human serum albumin (HSA) and a cationic surfactant-cetylpyridinium chloride (CPC), were studied at conditions close to physiological (50 mM HEPES or phosphate buffer, pH 7.4 and 160 mM NaCl) carrying out isothermal calorimetric titrations (ITC) at various temperatures (20-40 °C). ITC measurements indicated that the small endothermic changes associated with CPC demicellization were temperature independent at these conditions. Surprisingly, important enthalpy changes associated with binding of CPC to HSA were exothermic and temperature independent at lower concentrations (below 0.022 mM) of CPC and endothermic and temperature dependent at higher concentrations of CPC. The values of heat capacity changes were obtained for each studied concentration of CPC from the plot of enthalpy changes vs temperature. The obtained results demonstrate the temperature independence of heat capacity changes at entire range of studied CPC concentrations. Both enthalpograms and heat capacity curves indicate the two-step mechanism of HSA folding changes due to its interactions with CPC. The first step corresponds to transition from native state to partially unfolded state and the second to unfolding and to the loss of tertiary structure. The analysis of the results indicates that predominant cooperative unfolding occurs at CPC/HSA molar ratio region between 25 and 30. Such information could not be extracted from thermograms and describes the role of heat capacity as a major thermodynamic quantity giving insight on physical, mechanistic and even atomic-level into how HSA may unfold and interact with CPC. The effect of CPC binding on HSA intrinsic fluorescence, UV-Vis and CD spectra were also examined. Hence, the analysis of spectral data confirms the ITC results about the biphasic mechanism of HSA folding changes induced by CPC. The CD measurement also represents the conservation of considerable secondary structure of HSA due to interaction with CPC. © 2007 Elsevier Inc. All rights reserved.
Journal of Agricultural and Food Chemistry (00218561)56(16)pp. 7528-7534
Bovine β-lactoglobulin (β-LG) in vivo (in milks) has been found in complexes with lipids such as butyric and oleic acids. To elucidate the still unknown structure-function relationship in this protein, the structural changes of β-lactoglobulin variant A (β-LG A) in the presence of anionic surfactant such as sodium n-dodecyl sulfate (SDS) and in the presence of nonionic surfactant such as Triton X-100 have been investigated. Subsequently, the retinol binding by β-LG has been investigated in the presence of various amounts of these surfactants as its binding indicator. The results of UV-vis and fluorescence studies show a higher denaturating effect of SDS at acid pH that can be due to greater positive charges of β-LG at this pH indicating also the nonspecific hydrophobic interactions of Triton X-100 with β-LG at all studied pHs. Isothermal titration calorimetry (ITC) measurements indicate the endothermic nature of β-LG/SDS interactions and the exothermic nature of Triton X-100/β-LG interactions. The analysis of the binding data demonstrates the absence of considerable changes in retinol binding properties of β-LG in the presence of various amounts of these surfactants. This implies that surfactant binding does not change the conformation of β-LG in the regions defining the retinol-binding site. © 2008 American Chemical Society.
Colloids and Surfaces B: Biointerfaces (09277765)55(1)pp. 84-89
Human serum albumin (HSA) is frequently used in biophysical and biochemical studies since it has a well-known primary structure and it has been associated with the binding of many different categories of small molecules. In the present study, results are presented for the binding of cetylpyridinium chloride (CPC) with HSA at various pH and 25 °C, as monitored using ion selective membrane electrodes and fluorescence spectroscopy of intrinsic tryptophan. The obtained binding isotherms were analyzed on basis of binding capacity concept and Hill plot in order to determine the Hill parameters of binding sets. The system behaved as a system with two sets of binding sites in all studied situations. The results represent a positive cooperative behavior and the essential role of hydrophobic interactions in both binding sets. The intrinsic binding affinity of second binding set have a similar values and trends at acidic and neutral pHs, that represents the similar unfolded structure at these pHs. CPC quenched the fluorescence arising from Trp group incorporated to HSA. A biphasic behavior was observed in quenching process that confirmed the results of binding study correspond to the existence of two binding sets. The similarity of unfolded structure in acidic and neutral pH was also confirmed by fluorescence study. The quenching of HSA fluorescence takes place with a Stern-Volmer constant of 0.643 × 104, 1.23 × 104 and 7.40 × 104 at pH 3.5, 6.8 and 9.5, respectively. The Stern-Volmer behavior observed at low molar ratio of [CPC]/[HSA] (about 6), that represents the occurrence of conformational changes after this molar ratio. Comparing, the KSV values and binding parameters indicate that the binding is dominated by hydrophobic effects and, in minor degree, by electrostatic interactions. © 2006 Elsevier B.V. All rights reserved.
Significant advances have been made in the recent past for design and development of drug delivery systems. Dendrimers are a class of hyperbranched polymers that originate from a central core with repetitive branching units, forming a globular structure. Dendrimers have developed into an interesting material for biochemical applications because they have suitable structural properties and controlled size. On the other hand, magnetic nanoparticles (MNPs) are an extensively studied subclass of nanomaterials and they are known for their high magnetization and biocompatibility. As a result they can be utilized in various biomedical fields, including targeted drug delivery and biosensing. Recently, researchers have launched into combining the unique properties of dendrimer chemistry with the MNPs to offer a convenient to obtain platform for improved therapeutics and biomedical applications. Herein, we intend to present the developments made in dendrimer fabrication and dendrimers-based MNPs with varied surface structures and their contribution toward theranostics. © 2017 Elsevier Inc. All rights reserved.
Carbon nanotubes (CNTs) are new materials with promising applications in biotechnology. Drug delivery, biomedical imaging, nanoresonator sensors, are carbon-based tissue are some of the applications of CNTs. Researchers have agreed that CNTs hold significant antimicrobial activities against different pathogens (Gram-negative and -positive bacteria, fungal pathogens) such as human gut bacteria, Escherichia coli, Staphylococcus aureus, Salmonella enteric, etc. Recent results have shown that CNTs can be promising alternatives to antibiotics for annihilation of multidrug-resistant bacterial strains. The antimicrobial activity of CNTs is dependent on different factors, one of which is decorated functional groups. Here, the methods of CNT functionalization and their antimicrobial activity in the presence of different functional groups are investigated. © 2016 Elsevier Inc. All rights reserved.
