Hybrid nanoparticles of tetraamino fullerene and benzothiadiazole fluorophore as efficient photosensitizers against multidrug-resistant bacteria

Abstract

Antimicrobial photodynamic therapy has emerged as an innovative and promising alternative treatment for mitigating the prevalence of multidrug-resistant bacterial pathogens. Herein, a facile approach for the construction of stable hybrid nanoparticles based on the non-covalent conjugation of tetraamino fullerene with benzothiadiazole fluorophore is reported. Various characterization techniques were employed to verify the biocompatibility, structural, photophysical and photochemical properties of the as-synthesized hybrid nanoparticles. Such confined nanocompartment favored efficient energy or electron transfer between the fullerene and fluorophore, thus leading to 80.8 % fluorescence quenching and enhanced photodynamic therapy (PDT) efficiency. Compared with the individual fullerene, the resulting compact nanoparticles in water not only generated more hydroxyl radicals, but also exclusively produced a large amount of singlet oxygen, thereby creating an 18-fold increase in reactive oxygen species (ROS) yield. Therefore, 20 μg/mL of positively charged hybrid nanoparticles could selectively eliminate 99.9 % of methicillin-resistant Staphylococcus aureus (MRSA) and greatly inhibit their biofilm formation after merely 10 min of visible light exposure. These results offer new insights and strategies for the design of novel photosensitizers composed of fullerenes and light-harvesting dyes against multidrug-resistant bacterial and associated infections.