Light-activated antimicrobial polymers with citronellol-enhanced bacterial accumulation for on-demand disinfection

Antibacterial photodynamic therapy offers a promising approach for combating both susceptible and multidrug-resistant pathogens. However, conventional photosensitizers have limitations in terms of poor binding specificity and weak penetration for pathogens. In this study, we developed synergistic photobactericidal polymers that integrate hydrophilic toluidine blue O (TBO) with the lipophilic penetration enhancer citronellol (CT). The CT-containing monomer was copolymerized with glycidyl methacrylate, and then TBO was introduced via the epoxy group's ring-opening reaction. By combining the cationic charge and singlet oxygen (¹O₂) generation abilities of TBO with citronellol's membrane disrupting ability, the resulting copolymers have enhanced antimicrobial efficacy against Gram-positive, Gram-negative, and multidrug-resistant bacteria. CT not only enables the polymer to self-assemble and enhances the interaction between the polymer and bacteria, but also promotes the accumulation of TBO within cells by improving membrane permeability. ¹O₂ generated in specific subcellular regions maximizes photodynamic therapy's therapeutic potential. Furthermore, these copolymers can be used to develop light-activated antimicrobial polydimethylsiloxane that prevents bacterial adhesion and enables on-demand disinfection.