Abstract
Utilised for decades in cancer therapy, the application of photosensitisers in antimicrobial photodynamic therapy is now well explored. In a smart wound dressing, an externally triggered antimicrobial strategy would enable on-demand infection eradication. Hence, in this work, the light-initiated production of reactive oxygen species from photosensitiser-loaded nanocarriers was explored. Such systems enable highly localised delivery of photosensitiser, without associated "dark toxicity" effects. The amphiphilic block copolymer PEG-block-PLA was synthesised via ring-opening polymerisation in the melt. Via the solvent shift method, the polymer was self-assembled into nanosized vesicles encapsulating Phloxine B, a commercial water-soluble photosensitiser. In vitro bacteria experiments with Phloxine B-loaded vesicles relied on localised illumination with green light (530 nm, 4 mW cm(-2), 15 minutes) to generate (1)O(2), killing the bacterial cells. A 6.8 log(10) reduction in CFU mL(-1) for Staphylococcus aureus and a 4.7 log(10) reduction in CFU mL(-1) for Pseudomonas aeruginosa are reported. Incorporation of these vesicles into a support matrix in combination with a reporter dye could provide a pathway towards promising smart wound dressings.