Chitosan-coated cobalt ferrite nanocomplexes with dual antimicrobial activity and hemocompatibility

Abstract

The escalating prevalence of antibiotic-resistant bacterial infections represents a critical global health challenge, necessitating the development of alternative antimicrobial strategies that are both effective and biocompatible. Nanomaterials offer a versatile platform in this regard, as their physicochemical properties can be tailored to enhance antibacterial performance. Among these, cobalt ferrite nanoparticles (CFs) exhibit attractive magnetic properties, chemical stability, and multifunctionality for biomedical applications; however, their clinical translation is hindered by aggregation, limited colloidal stability, and potential biocompatibility concerns. Building on our previous work demonstrating the biocompatibility and imaging potential of chitosan (CH)-coated CFs (CCFs), this study investigates their antibacterial efficacy against a diverse panel of Gram-positive (Bacillus subtilis RBW and Staphylococcus aureus) and Gram-negative bacteria (enteropathogenic Escherichia coli EPEC, E. coli DH5α, E. coli K-12, Salmonella typhi AF-4500, Shigella flexneri 3C, and Vibrio cholerae). Antibacterial activity was evaluated using the zone of inhibition (ZOI), minimum inhibitory concentration (MIC), and CellTox™ Green assays. CCFs demonstrated significantly enhanced antibacterial activity compared to CH alone or uncoated CFs, highlighting the synergistic contribution of the chitosan coating. Notably, S. aureus exhibited the highest susceptibility, with a maximum ZOI of ∼26.45 mm at 500 µg of CCFs. Elevated levels of malondialdehyde–thiobarbituric acid adducts following treatment suggest that membrane oxidative damage is a key mechanism underlying bacterial killing. Importantly, hemocompatibility assessments using rat and human erythrocytes revealed concentration-dependent cytotoxicity, indicating that CCFs maintain acceptable blood compatibility within a defined concentration range. Collectively, this study establishes CCFs as a promising dual-functional platform combining potent broad-spectrum antimicrobial activity with tunable hemocompatibility, underscoring their potential for future biomedical applications, provided that an optimal therapeutic window is carefully defined.