Photocatalytic Antibacterial and Antibiofilm Activities of Subphthalocyanine/TiO₂ Derivates: Integrating Experimental Findings with Molecular Docking and Dynamics

The antibacterial and antibiofilm properties of SubPcs were investigated against the pathogenic bacteria E. coli, S. aureus, and MRSA. SubPcs have demonstrated the highest efficacy against S. aureus, achieving antibacterial effects of around 100% through LED light exposure. This was followed by the observed effects of 76% on E. coli and 56% on MRSA. The GSH depletion assay revealed that SubPc-3 demonstrated the highest depletion rate of 82% when exposed to LED light. Fluorescence and SEM analyses were carried out to confirm bacterial membrane damage activities of SubPcs. Molecular docking and dynamics simulations were applied for the understanding of the molecular mechanisms. The in-silico investigations offered useful insights into the potential binding mechanisms and interactions of SubPcs with the essential bacterial proteins. These findings supported our experimental results and gave molecular reasons for the observed antibacterial effects. Furthermore, the photocatalytic antibacterial mechanism of SubPcs/TiO₂ has been clarified by analyzing the electronic band levels of SubPcs and TiO₂. This analysis has provided insights into the mechanism of ROS formation under light irradiation. The combination of experimental and computational methods in this study not only shows the effectiveness of SubPcs but also enhances our comprehension of their molecular mechanisms. Hence, it is hypothesized that these harmless SubPcs will provide valuable insights for future studies on non-antibiotic photochemical antimicrobials, presenting a hopeful strategy to combat antibiotic-resistant bacteria by utilizing both photocatalytic activity and specific protein interactions.