| Abstract [eng] |
Biofilm-associated infections remain a major healthcare problem, particularly in medical devices and high-touch surfaces. Antimicrobial photodynamic surfaces offer a potential strategy for controlling bacterial attachment because they generate reactive oxygen species only after light activation. In this study, fullerene C₆₀ was incorporated into poly (lactic acid) (PLA), poly(3-hydroxy-butyrate-co-3-hydroxyvalerate) (PHBV), and chitosan films to develop light-activated antimicrobial biopolymer surfaces against Staphylococcus aureus. PLA and PHBV composites were prepared by thermomechanical processing, whereas chitosan films were fabricated by hot pressing after manual premixing with C₆₀ and plasticisers. Raman spectroscopy confirmed C₆₀ incorporation in all films; however, Raman mapping showed that fullerene was not uniformly dispersed and instead formed matrix-dependent C₆₀-rich domains. XRD and DSC analyses further showed that C₆₀ affected each polymer differently: PHBV-C₆₀ exhibited the most structurally stable response, PLA-C₆₀ showed strong fullerene heterogeneity and reduced crystallinity, and chitosan-C₆₀ showed phase-separated C₆₀ domains and water-dependent thermal behaviour. All C₆₀-containing films generated singlet oxygen under 450 nm blue-light irradiation, confirming that the fullerene retained its photodynamic activity after processing. PLA-C₆₀ produced the highest ROS signal, followed by PHBV-C₆₀ and chitosan-C₆₀. Microbiological assays confirmed the light-dependent antibacterial activity against surface-associated S. aureus. PLA-C₆₀ was the most effective during bacterial attachment, whereas PHBV-C₆₀ showed the strongest reduction in pre-attached cells. Chitosan-C₆₀ remained photoactive but exhibited the weakest antibacterial performance. Overall, the results demonstrate that thermophysically processed C₆₀-containing biopolymer films can function as light-activated antimicrobial surfaces. The effectiveness of these materials depends strongly on the polymer matrix, indicating that fullerene distribution, ROS generation, and bacterial interaction with the surface must be considered together when designing photoactive antimicrobial coatings. |
