Chitosan and L-histidine coated biofunctional TiO₂ composite with enhanced ROS-mediated antimicrobial and anticancer efficacy for biomedical applications.

Societies continue to face the urgent challenge of developing effective, safe, and stable nanoparticles with promising biomedical applications. Herein, the present study synthesis chitosan and L-Histidine dually coated titanium dioxide (TiCSLH) nanocomposite (NC) by chemical co-precipitation method. The antimicrobial performance of TiO₂ nanoparticles is closely linked to their physicochemical properties, such as reduced particle size, increased bandgap, and the presence of oxygen vacancies, all of which collectively enhance reactive oxygen species (ROS) generation and inhibit microbial growth. Structural analyses using XRD and TEM confirmed that TiCSLH nanoparticles possess an anatase phase and a spherical morphology. Compared to TiO₂, TiCSLH nanoparticles demonstrated significantly enhanced antimicrobial activity against MRSA, E. coli, K. pneumoniae, P. aeruginosa and C. albicans strains, as evidenced by larger zones of inhibition from 23-24 mm. This enhanced efficacy is attributed to their smaller particle size (~ 26 ± 3 nm), wider bandgap (3.34 eV), and prominent oxygen vacancy-related emissions at 518 and 531 nm, which facilitate increased ROS production, resulting in cellular membrane disruption and microbial death. Furthermore, compared to TiO