Hydroxyapatite-boosted Fe3O4 nanozymes with enhanced peroxidase-like activity for multiplex biosensing of ascorbic acid/uric acid and serum total antioxidant capacity

Abstract

The well-established link between elevated oxidative stress and numerous diseases underscores the critical role of antioxidant intake in maintaining physiological homeostasis. Consequently, the development of precise and innovative methodologies for evaluating the antioxidant capacity of various substances and assessing the total antioxidant capacity of blood serum is essential for biomedical research and clinical diagnostics. In this study, hydroxyapatite-functionalized iron oxide nanoparticles (Fe3O4@HAp), which exhibit peroxidase-like activity, were synthesized via a solvothermal method. Hydroxyapatite (HAp) functionalization significantly enhanced catalytic performance, resulting in a 90 % increase in the specific activity of Fe3O4@HAp compared to bare Fe3O4. Kinetic analysis revealed that Fe3O4@HAp nanozymes exhibited improved K m and ν max for both 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2) substrates. The efficacy of the synthesized nanoparticles in quantifying the free radical scavenging capacity of ascorbic acid and uric acid, two antioxidants present in serum, was evaluated. The system demonstrated low limits of detection (LOD) of 0.09 µg/mL for ascorbic acid and 1.01 µg/mL for uric acid. Furthermore, a comparative assessment of total antioxidant capacity (TAC) in serum samples revealed significant disparities in antioxidant levels between healthy individuals and patients, highlighting the potential of the Fe3O4@HAp nanozyme system as a valuable diagnostic tool for assessing oxidative stress and related pathologies. As a result, Fe3O4@HAp nanozymes represent a promising platform for the rapid, high-throughput assessment of antioxidant capacity in clinical and biomedical applications. © 2025 Elsevier B.V.