ARABIAN JOURNAL OF CHEMISTRY (18785352)17(9)
This research aimed to fabricate and evaluate Poly(lactic acid)/poly(epsilon-caprolactone)/graphene (PLA/PCL/G) nanocomposite scaffolds for peripheral nerve tissue engineering. To achieve this goal, scaffolds were fabricated using the fused deposition modeling (FDM) 3D printing method with the following compositions: 50 wt% PLA50 wt% PCL (PLA-PCL), 98.5 wt% PLA-1.5 wt% G (PLA-G), 98.5 wt% PCL-1.5 wt% G (PCL-G), and 50 wt% PLA48.5 wt% PCL-1.5 wt% G (PLA-PCL-G). The microstructure and chemical composition of the scaffolds were characterized using SEM, XRD, and FTIR. SEM images revealed that the PLA-PCL-G scaffold exhibited a more regular and uniform morphology compared to the others, with the PLA-PCL scaffold displaying the least regularity. The porosity percentage and pore size of the scaffolds ranged from 50 % to 86 % and 300 to 500 mu m, respectively. Mechanical properties were assessed via compression testing, indicating that the elastic modulus of the PLA-PCL-G scaffold was approximately 22.36 MPa, suitable for peripheral nerve tissue applications. Electrical conductivity testing showed that PLA-PCL-G had a conductivity of about 8.2E-5S/cm, similar to PLA-G. Biodegradability was evaluated by immersing samples in phosphate-buffered saline (PBS), revealing that PLAPCL-G exhibited a weight loss of approximately 1.3 % and a degradation rate of 0.14 mm/day over four weeks, closely matching peripheral nerve tissue regeneration rates. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide) assay results confirmed that PLA-PCL-G scaffolds were non-cytotoxic to PC12 cells. Overall, these findings suggest that the 50 wt% PLA-48.5 wt% PCL-1.5 wt% G scaffold holds promise for peripheral nerve tissue engineering applications.
The aim of this research was to fabricate and evaluate polyglycerol sebacate/polycaprolactone/reduced graphene oxide (PGS-PCL-RGO) composite scaffolds for myocardial tissue engineering. Polyglycerol sebacate polymer was synthesized using glycerol and sebacic acid prepolymers, confirmed by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Six PGS-PCL-RGO composite scaffolds (S1-S6) with various weight ratios were prepared in chloroform (CF) and acetone (Ace) solvents at 8 CF:2Ace and 9 CF:1Ace volume ratios, using the electrospinning method at a rate of 1 ml/h and a voltage of 18 kV. The scaffolds' chemical composition and microstructure were characterized by FTIR, XRD, and scanning electron microscopy (SEM). Further investigations included tensile testing, contact angle testing, four-point probe testing for electrical conductivity, degradation testing, and cytotoxicity testing (MTT). The results showed that adding 2%wt RGO to the composite scaffold decreased fiber diameter and degradation rate, while increasing electrical conductivity and ductility. The 33%PGS-65%PCL-2%RGO (S3) composite scaffold exhibited the lowest degradation rate (23.87 % over 60 days) and the highest electrical conductivity (51E-3 S/m). Mechanical evaluations revealed an elastic modulus of 2.46 MPa and elongation of 62.43 %, aligning closely with the heart muscle's elastomeric properties. The contact angle test indicated that the scaffold was hydrophilic, with a water contact angle of 61 ± 2°. Additionally, the cell toxicity test confirmed that scaffolds containing RGO were non-toxic and supported good cell viability. In conclusion, the 33%PGS-65%PCL-2%RGO composite scaffold exhibits mechanical and structural properties similar to heart tissue, making it an ideal candidate for myocardial tissue engineering. © 2024 The Authors
Metals and Materials International (15989623)29(1)pp. 192-203
In this work, the effect of the accumulative roll bonding (ARB) process on the microstructure, mechanical properties, and corrosion characteristics of AZ31 Mg alloy was investigated. First, the ARB process up to 3 cycles at 350 °C was applied to annealed AZ31 Mg alloy sheets. Then, all samples were characterized via microstructure observations, mechanical investigations, and also, electrochemical analyses, and immersion tests in simulated body fluid (SBF) solution. In addition, the L929 cell line was used to evaluate the cytotoxicity of the samples. The obtained results showed that after the third ARB cycle, the average grain size in the annealed sample decreased from ~ 14 to ~ 3 µm. Some ultra-fine grained (UFG) microstructures that had a grain size of fewer than 1 μm were also observed in the 3-cycle ARB-processed sample. This grain refinement led to an increase in the yield strength and micro-hardness values of the annealed sample from ~ 153 MPa, and ~ 55 Hv to ~ 214 MPa, and ~ 76 Hv. However, the ARB process had an adverse effect on the corrosion characteristics of samples, and the corrosion rate increased after the ARB process. Moreover, the viability of L929 cells in culture media containing extracts obtained from the annealed sample was higher than that for the 3-cycle ARB-processed sample after 3 days of incubation. The influence of microstructural evolution in the ARB-processed AZ31 Mg alloy on the corresponding mechanical properties, corrosion behaviors, and cytotoxicity results was discussed in detail. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s) under exclusive licence to The Korean Institute of Metals and Materials.
Arabian Journal Of Chemistry (18785352)16(6)
The aim of this study was to fabricate and evaluate magnesium-zinc-graphene oxide nanocomposite scaffolds for bone tissue engineering. For this reason, Mg-6Zn, Mg-6Zn-1GO, and Mg-6Zn-2GO scaffolds were fabricated by the powder metallurgy method. The porosity level and also the pore size of the scaffolds were evaluated by SEM which varied from 40 to 46% and 200 to 500 μm, respectively. The chemical composition and microstructure of the scaffolds were characterized by XRD and SEM equipped with EDS; the presence of Mg, Zn, C, and O elements in the structure of the scaffolds was shown. Also, the elemental map confirmed the existence of magnesium, zinc, carbon, and oxygen in the structure of the scaffold. The mechanical properties of the scaffolds were investigated by the compression test; the results showed that by the addition of graphene oxide to the structure, the compressive strength of the samples increased from 5 to 8 MPa. Electrochemical corrosion polarization tests were conducted to evaluate the corrosion resistance of the samples immersed in simulated body fluid (SBF). Furthermore, the biodegradability of the scaffolds was determined by immersion of the samples in phosphate-buffered saline (PBS). The results demonstrated that the polarization resistance value and the corrosion rate for different formulations including Mg-6Zn, Mg-6Zn-1GO, and Mg-6Zn-2GO were 41.58, 35.48, and 55.40 Ω.cm2 followed by 10.60, 14.83, and 9.06 mm.year−1, respectively. Based on the results, the Mg-6Zn-2GO formulation presented the best corrosion resistance among the samples were investigated, which confirmed the results of the immersion test. Moreover, the MTT assay proved that the extract of Mg-6Zn-2GO scaffolds was not cytotoxic in contact with L-929 cells which validated the studied scaffolds for bone tissue applications. © 2023 The Author(s)
Journal of Alloys and Compounds (09258388)892
In this research, surface modification of the Ti6Al4V titanium alloy, by calcium phosphate/graphene composite coatings, was considered to improve the bioactivity and biocompatibility of Ti6Al4V for biomedical applications. Synthetic biphasic calcium phosphate (BCP), derived from bovine bone, with 1%wt. Graphene (Gr) and without Gr, was coated by electrophoretic deposition on Ti6Al4V substrates to improve the bioactivity of surface and the corrosion resistance of electrophoretic coating. Different methods were conducted to characterize and compare the chemical and biological properties of BCP and BCP/Gr coatings. Results revealed that the presence of graphene in BCP/Gr composite coatings led to enhanced mechanical and corrosion resistance properties while composite coating remained bioactive and hydrophilic. Moreover, MTT assay and cell attachment results indicated that BCP/Gr coatings improved the MG-63 cell viability, which was approximately 87% for 7 days. The BCP/Gr coating is a novel and proper choice to modify Ti6Al4V surface properties for biomedical applications. © 2021 Elsevier B.V.
Journal Of Medical Signals And Sensors (22287477)10(4)pp. 260-266
Background: Spironolactone (SP) is a lipophilic aldosterone receptor antagonist that few studies have reported its effect on cardiac remodeling. In addition, fewer researches have considered its influence on cardiomyocyte viability and potential benefits for myocardial tissue remodeling. Method: In this study, stearic acid (SA) (solid lipid) and oleic acid (OA) (liquid lipid) were utilized to produce nanostructured lipid carries (NLCs) (various ratios of SA to OA and water amount, F1: 80:20 [30 ml water], F2: 80:20 [60 ml water], F3: 70:30 [30 ml water], and F4: 70:30 [60 ml water]) containing SP and their particle size, polydispersity index, zeta potential, entrapment efficiency, and release profile were measured. The purpose of encapsulating SP in NLCs was to provide a sustain release system. Meanwhile, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay with different concentrations of SP-loaded NLCs (SP-NLCs) was conducted to evaluate the cytotoxicity of the NLCs on rat myocardium cells (H9C2). Results: Increase of oil content to 10 wt% reduced the particle size from 486 nm (F1) to 205 nm (F2). Zeta potential of the samples at around −10 mV indicated their agglomeration tendency. After 48 h, SP-NLCs with the concentrations of 5 and 25 μM showed significant improvement in cell viability while the same amount of free SP-induced cytotoxic effect on the cells. SP-NLCs with higher concentration (50 μM) depicted cytotoxic effect on H9C2 cells. Conclusion: It can be concluded that 25 μM SP-NLCs with sustain release profile had a beneficial effect on cardiomyocytes and can be used as a mean to improve cardiac tissue regeneration. © 2020 Journal of Medical Signals & Sensors | Published by Wolters Kluwer - Medknow
Materials Research Express (20531591)6(7)
The main purpose of this study was to fabricate a magnesium/nano-hydroxyapatite porous composite with appropriate mechanical properties and degradation rate for biomedical applications. Magnesium scaffolds including different weight of nano-hydroxyapatite (0, 2, 4 and 8%) were fabricated using the powder metallurgy method. To study the phase and microstructure, the samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Measurement of the mechanical properties was performed using a compression test, and the porosimetry test was performed by following the Archimedes method. Biodegradation properties of the specimens were evaluated by soaking in the phosphate-buffered saline (PBS). Based on the results, composites with 2 and 4 wt% of nano-hydroxyapatite (nHA) had the optimum characteristics; the yield strength of these composites was about twice and the plateau stress was about three to four times more than that of the pure magnesium. Also, the elastic modulus of these composites (0.25 GPa) was in cancellous bone range. The degradation rate of the composites with 2 and 4 wt% of nano-hydroxyapatite, as compared with pure magnesium, was decreased about 35 to 40 percent. Mg/nHA composite including 2-4 wt% of hydroxyapatite could be, therefore, considered as an appropriate alternative material for degradable load bearing implantation. © 2019 IOP Publishing Ltd.
Journal Of Medical Signals And Sensors (22287477)9(1)pp. 33-41
Background: The aim of this study was to make a bioactive bone cement based on poly (methyl methacrylate) (PMMA) with suitable mechanical properties. Methods: PMMA has been modified by fabricating a composite consisting of biphasic calcium phosphate (BCP) 68 wt%, PMMA 31 wt% and graphene (Gr) 1 wt% (PMMA/BCP/Gr), 32 wt% of PMMA, and 68 wt% of BCP (PMMA/BCP) and pure PMMA by milling, mixing with monomer liquid, and casting. The modified cements were evaluated regarding mechanical properties, bioactivity, degradation rate, and biocompatibility. Results: The scanning electron microscopy (SEM) images of hydroxyapatite (HA) formed on samples surface after 28 days of immersion in simulated body fluid (SBF) demonstrated that bioactivity was obtained due to the addition of BCP, and the degradation rate of the cement was enhanced as well. Investigations of mechanical properties revealed that BCP increased the elastic modulus of PMMA more than 1.5 times, but predictably decreased elongation. The addition of 1 wt% Gr increased elongation and yield strength from 16.39% ± 1.02% and 61.67 ± 1.52 Mpa for PMMA/BCP to 35.18% ± 2.42% and 78.40 ± 2.06 Mpa for PMMA/BCP/Gr, respectively. MG63 cells survival and proliferation improved from 127.55% ± 7.03% for PMMA to 201.41% ± 10.7% for PMMA/BCP/Gr on Day 4 of culture. Conclusion: According to the obtained results of mechanical and biological tests, it seems that new PMMA/BCP/Gr bone cement has a potentiality for usage in orthopedic applications. © 2019 Journal of Medical Signals & Sensors.
Materials Chemistry and Physics (02540584)222pp. 147-151
The aim of this study was designing and fabricating nano-composite scaffolds based on polyglycerol sebacate in order to use in nerve tissue engineering. Semi-crystalline polyglycerol sebacate polymer was synthesized and evaluated by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) methods. The synthesized polyglycerol sebacate was electrospun with chitosan and gelatin at different concentrations under various conditions. The obtained samples were examined using Scanning electron microscopy (SEM) observations; the diameters of fibers were measured via image processing method, and the percentage of scaffolds porosity were obtained as well. Results demonstrated that semi-crystalline polyglycerol sebacate/chitosan/gelatin could be electrospun to produce fibers with the diameter of about 80 nm in average. MTT assay were performed using PC12 cell line; after 3 days of cell culture, it seems that polyglycerol sebacate/Chitosan/Gelatin nano-composite has potentiality for nerve tissue engineering applications. © 2018 Elsevier B.V.
Journal of Bioactive and Compatible Polymers (15308030)33(5)pp. 529-542
In this study, mechanical, electrical, physical, and biological properties of polymeric matrixes comprising poly(glycerol-sebacate) (PGS) and poly(caprolactone) (PCL) with various weight ratio of PGS:PCL (1:3 and 1:1) were evaluated in order to apply as nerve guidance conduit. For this purpose, synthetic PGS pre-polymer was acquired using poly-condensation of glycerol and sebacic acid and characterized by attenuated total reflection-fourier transformed infrared (ATR-FTIR) and X-ray diffraction (XRD) spectroscopies. Furthermore, the effect of 1 wt% graphene (Gr) Nano sheets incorporation as filler, was investigated. Blending PGS with PCL significantly improves the hydrophilicity of the samples and improves cells attachment; however, their mechanical properties decreased dramatically. Presence of Gr within the polymeric matrix, significantly increased elastic modulus and tensile strength, which is possibly attributed to its superior mechanical properties and high aspect of ratio. Moreover, aforementioned polymeric matrixes, turned to conductive membranes by addition of Gr, which affected drastically on their biological properties; that way, 3, 4, 5-dimethylthiazol-2, 5-diphenyl tetrazolium bromide assay elucidated that only addition of 1 wt% Gr to the polymeric films resulted in improved cell survival and cell attachment for 7 days of cell seeding. In addition, cell attachment was enhanced considerably by increasing PGS up to 50 wt%, due to positive role of PGS on contact angle reduction. Therefore, the nano-composite film (50PGS-50PCL-1Gr) can be a promising substrate to use as a nerve guidance conduit. © The Author(s) 2018.
Journal Of Medical Signals And Sensors (22287477)7(3)pp. 170-177
Background: After total hip arthroplasty, there would be some problems for the patients. Implant loosening is one of the significant problems which results in thigh pain and even revision surgery. Difference between Young's modulus of bone-metal is the cause of stress shielding, atrophy, and subsequent implant loosening. Materials and Methods: In this paper, femoral stem stiffness is reduced by novel biomechanical and biomaterial design which includes using proper design parameters, coating it with porous surface, and modeling the sketch by the software. Parametric design of femoral stem is done on the basis of clinical reports. Results: Optimized model for femoral stem is proposed. Curved tapered stem with trapezoidal cross-section and particular neck and offset is designed. Fully porous surface is suggested. Moreover, Designed femoral stem analysis showed the Ti6Al4V stem which is covered with layer of 1.5 mm in thickness and 50% of porosity is as stiff as 77 GPa that is 30% less than the stem without any porosity. Porous surface of designed stem makes it fix biologically; thus, prosthesis loosening probability decreases. Conclusion: By optimizing femoral stem geometry (size and shape) and also making a porous surface, which had an intermediate stiffness of bone and implant, a more efficient hip joint prosthesis with more durability fixation was achieved due to better stress transmission from implant to the bone.
Salehi, H.,
Mehrasa, M.,
Nasri-nasrabadi, B.,
Doostmohammadi, M.,
Seyedebrahimi, R.,
Davari, N.,
Rafienia m., M.,
Ebrahimian hosseinabadi, M.,
Agheb, M.,
Siavash, M. Journal Of Research In Medical Sciences (17357136)22(9)
Background: Wound healing is a complex biological process. Some injuries lead to chronic nonhealing ulcers, and healing process is a challenge to both the patient and the medical team. We still look forward an appropriate wound dressing. Materials and Methods: In this study, starch-based nanocomposite hydrogel scaffolds reinforced by zeolite nanoparticles (nZ) were prepared for wound dressing. In addition, a herbal drug (chamomile extract) was added into the matrix to accelerate healing process. To estimate the cytocompatibility of hydrogel dressings, fibroblast mouse cells (L929) were cultured on scaffolds. Then, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium-bromide assay test and interaction of cells and scaffolds were evaluated. For evaluating healing process, 48 male rats were randomly divided into four groups of four animals each (16 rats at each step). The ulcers of the first group were treated with the same size of pure hydrogels. The second group received a bandage with the same size of hydrogel/extract/4 wt% nZ (hydrogel NZE). The third group was treated with chamomile extract, and the fourth group was considered as control without taking any medicament. Finally, the dressings were applied on the chronic refractory ulcers of five patients. Results: After successful surface morphology and cytocompatibility tests, the animal study was carried out. There was a significant difference between starch/extract/4 wt% nZ and other groups on wound size decrement after day 7 (P < 0.05). At the clinical pilot study step, the refractory ulcers of all five patients were healed without any hypersensitivity reaction. Conclusion: Starch-based hydrogel/zeolite dressings may be safe and effective for chronic refractory ulcers. © 2017 Journal of Research in Medical Sciences.
Materials Science and Engineering C (09284931)79pp. 66-75
In the present study, polyethylene glycol fumarate (PEGF) was synthesized as a component of blend solutions via polycondensation polymerization and characterized by different tests in order to determine its functional groups and its physical properties included melting and crystallization temperature, enthalpy of fusion and average molecular weights. Wound dressing films based on chitosan (Ch), PEGF and thymol (Th) were fabricated by solvent casting method with different formulations contained 80%(w/w) chitosan and 20%(w/w) PEGF as polymeric components and different amounts of thymol consisted of 0, 0.6, 1.2 and 1.8%(v/v) as pharmaceutical additives of blend solutions. These films were evaluated by different essential tests included Fourier transform infrared spectroscopy (FTIR), tensile testing, water vapor transmission rate (WVTR), water vapor uptake, equilibrium water uptake, water solubility, swelling, scanning electron microscopy (SEM) and antibacterial activity tests. The blend film contained 1.8%(v/v) thymol demonstrated optimal properties included acceptable mechanical properties, better absorption of water vapor or liquid water, higher water vapor transmission rate and air permeability, acceptable water solubility, superior swelling level, more porous structures and rough surfaces and the excellent antibacterial activity against both gram-negative and gram-positive bacteria which make it a suitable candidate for wound dressing applications. © 2017 Elsevier B.V.
Tissue Engineering and Regenerative Medicine (17382696)13(6)pp. 684-690
This study aimed at examining and comparing the fabrication process, electrical conductivity, and biological properties of Chitosan/Graphene membranes and poly(D, L-lactic-co-glycolic acid) (PLGA)/Graphene membranes. Nano-composite membranes were made using chitosan or PLGA matrix, and 0.5–1.5 wt.% graphene nano-sheets as the reinforcement material; all the membranes were fabricated through solution casting method. Fourier transform infrared spectroscopy and X-ray diffraction results indicated that the graphene had been uniformly dispersed in polymeric matrix. The membranes with 1.5 wt.% graphene appeared to have the highest value of electrical conductivity among all the examined the membranes and this growth was about 106 in comparison with neat polymers. Since the Chitosan 1.5% graphene membrane was found to have the highest proliferation after 72 hours by MTT [3-(4, 5-di-methylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay of PC12 cell line (p<0.05), it is promising to consider nano-composite membrane for nerve tissue engineering applications. © 2016, The Korean Tissue Engineering and Regenerative Medicine Society and Springer Science+Business Media Dordrecht.
Journal Of Medical Signals And Sensors (22287477)6(4)pp. 237-242
In this paper, preparation, bioactivity, and osteoblast cell behavior of cortical bone derived nano-biphasic calcium phosphate (nano-BCP) are presented. The calcined bovine bone samples with the addition of di-ammonium hydrogen phosphate were heated at 700°C for 100 min, and thus nano-BCP with the composition of 63/37 hydroxyapatite (HA)/β-tricalcium phosphate (β-TCP) was produced. Scanning electron microscopy (SEM) images, energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis of immersed samples in simulated body fluid (SBF) solution showed that a uniform layer was formed on the surface after 7 days with the chemical composition of HA. The results indicated that the nano-BCP sample developed excellent bioactivity after 28 days. The nano-BCP samples showed better cell proliferation compared to pure HA samples. After 7 days in cell culture, the prepared nano-BCP (HA/β-TCP) exhibited the maximum proliferation of the MG-63 osteoblast cells. © 2016 Journal of Medical Signals and Sensors.
Naeimi, M.,
Rafienia m., M.,
Fathi, M.,
Janmaleki, M.,
Bonakdar, S.,
Ebrahimian hosseinabadi, M. International Journal of Polymeric Materials and Polymeric Biomaterials (1563535X)65(4)pp. 202-209
A silk fibroin-chondroitin sulfate-sodium alginate (SF-CHS-SA) porous scaffold containing chitosan nanoparticles (NPs) was investigated. The proliferation of adipose-derived stem cells (ASCs) was studied by SEM, fluorescent microscopy, alcian blue staining, dimethylmethylene blue assay, and real-time polymerization chain reaction. The results showed that incorporation of NPs into the scaffold improved compressive modulus (5.6 ± 0.15 MPa). The amount of glycosaminoglycan expression of the ASCs was reached to 8.9 ± 0.3 g/mL. The gene expressions of aggrecan, collagen II, and SOX9 of the ASCs were significantly improved. This study revealed that the prepared scaffold can be used as a substrate for cartilage tissue engineering. © 2016 Taylor & Francis Group, LLC.
Journal of Materials Science and Technology (10050302)27(12)pp. 1105-1112
In this paper, preparation of nano-biphasic calcium phosphate (nBCP), mechanical behavior and load-bearing of poly (lactide-co-glycolide) (PLGA) and PLGA/nBCP are presented. The nBCP with composition of 63/37 (w/w) HA/β-TCP (hydroxyapatite/β-tricalcium phosphate) was produced by heating of bovine bone at 700°C. Composite scaffolds were made by using PLGA matrix and 10-50 wt% nBCP powders as reinforcement material. All scaffolds were prepared by thermally induced solid-liquid phase separation (TIPS) at -60°C under 4 Pa (0.04 mbar) vacuum. The results of elastic modulus testing were adjusted with Ishai-Cohen and Narkis models for rigid polymeric matrix and compared to each other. PLGA/nBCP scaffolds with 30 wt% nBCP showed the highest value of yield strength among the scaffolds. In addition, it was found that by increasing the nBCP in scaffolds to 50 wt%, the modulus of elasticity was highly enhanced. However, the optimum value of yield strength was obtained at 30 wt% nBCP, and the agglomeration of reinforcing particles at higher percentages caused a reduction in yield strength. It is clear that the elastic modulus of matrix has the significant role in elastic modulus of scaffolds, as also the size of the filler particles in the matrix. © 2011 The Chinese Society for Metals.
Polymer Degradation and Stability (01413910)96(10)pp. 1940-1946
In this paper, the yield strength and elastic modulus of Poly (lactide-co-glycolide) (PLGA) and PLGA/nano-biphasic calcium phosphate (nBCP) composite scaffolds, before and during in-vitro degradation, have been evaluated. Composite scaffolds were made by using PLGA matrix and 10-50 wt.% nBCP powder as the reinforcement material. All scaffolds, with more than 89% porosity, were fabricated by thermally-induced phase separation (TIPS). During in-vitro degradation (0-8 weeks), the PLGA/nBCP scaffolds showed both more weight loss and better mechanical properties as compared to neat PLGA scaffolds. The PLGA/nBCP scaffolds with 30 wt.% nBCP illustrated the highest value of yield strength among the composite scaffolds, before and after degradation, until 6 weeks. After 8 weeks, the yield strength values were very poor and close to each other. The values of elastic modulus for all samples were less than the half of their initial values after 6 weeks. However, after 8 weeks, the elastic moduli of all samples reduced to negligible values. © 2011 Elsevier Ltd. All rights reserved.
Wear (00431648)260(1-2)pp. 123-127
In this research, the wear of electroless Ni-P and Ni-P-B4C composite coatings was reviewed. Auto catalytic reduction of Ni in nickel sulfate and sodium hypophosphate bath including suspended B4C particles with different concentration was used to create composite coatings with 12, 18, 25 and 33 vol.% of B4C particles. Coatings 35 μm thick were heat treated at 400 °C for one hour in an argon atmosphere and the wear resistance and friction coefficient of heat-treated samples were determined by block-on-ring tests. All wear tests were carried out at 24 °C, 35% moisture, 0.164 m/s sliding speed and about 1000 m sliding distance. Graphs show that an electroless Ni-P-B4C composite coating with 25 vol.% of B4C had the best wear resistance against a CK45 steel counterface. © 2005 Elsevier B.V. All rights reserved.
