Chitosan coated multifunctional NiFe₂O₄ nanocomposites as a promising candidate for biomedical applications.

Nanoparticles for biomedical applications often suffer from limited stability, low biocompatibility, and suboptimal therapeutic efficacy. To address these challenges, NiFe₂O₄ nanoparticles were functionalized with chitosan (NiFe₂O₄-CS) via a co-precipitation method, aiming to enhance their structural, optical, antimicrobial, and anticancer properties. XRD analysis revealed a reduction in crystallite size from 37 to 33 nm after chitosan modification, indicating controlled crystal growth and increased surface area. TEM results confirmed a corresponding decrease in particle size from 35 ± 2.1 nm to 29 ± 1.8 nm, improving surface reactivity and stability. PL spectra exhibited a red-shift in green emission peaks, suggesting increased oxygen vacancies and defect states that facilitate ROS generation. Antimicrobial assays against methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans (C.albicans) demonstrated significantly higher activity for NiFe₂O₄-CS nanocomposites, supported by SEM imaging that showed extensive microbial membrane disruption. Furthermore, NiFe₂O₄-CS exhibited enhanced anticancer activity against C6 glioma cells, with an IC₅₀ of 35.6 µg/mL compared to 43.6 µg/mL for unmodified nanoparticles. Zebrafish embryo studies confirmed the biocompatibility of NiFe₂O₄-CS at appropriate doses, although dose-dependent embryotoxicity was observed. These findings highlight that chitosan functionalization of dual-metal nanoparticles improves therapeutic efficacy through increased surface interactions and ROS generation while underscoring the need for careful dose optimization. This study presents a novel strategy for designing biopolymer-coated nanocomposites that balance enhanced biomedical performance with safety considerations.