Blue-Light Photoactivated Curcumin-Loaded Chitosan Nanoparticles Prepared by Nanoprecipitation and Ionic Gelation: A Promising Approach for Antimicrobial Photodynamic Inactivation

Antimicrobial photodynamic inactivation (aPDI) represents a promising alternative strategy for combating bacterial infections. This study investigates the potential of curcumin-loaded chitosan nanoparticles (CurChNPs) as novel nanoenabled photosensitizer agents for bacterial photoinactivation. CurChNPs were synthesized using an innovative dual synthesis approach by combination of nanoprecipitation and ionic gelation methods; their physicochemical properties were also characterized. The nanoparticles exhibited excellent solubility in aqueous solutions, high curcumin encapsulation efficiency (96%), and controlled release profile. Photoinactivation assays were conducted against <i>Staphylococcus aureus</i> (ATCC 25923) and <i>Escherichia coli</i> (ATCC 25922) to evaluate the efficacy of CurChNPs in aPDI. The nanoparticles exhibited significant photobactericidal activity when irradiated with blue light (450 nm, 28.84 mW·cm^-2). Mechanistic studies confirmed the generation of reactive oxygen species (ROS) as the primary mode of photoinactivation. Microscopy analyses revealed structural damage to bacterial cell membranes, culminating in cell lysis. These findings highlight the synergistic effects of the photodynamic activity of curcumin and the antimicrobial activity of chitosan, demonstrating that CurChNPs are a promising platform for the eradication of bacterial infections. This work contributes to the development of sustainable, nanotechnology-based approaches for addressing bacterial infections, particularly against resilient Gram-negative pathogens. Future studies may explore the potential of CurChNPs against antibiotic-resistant bacterial strains.