Development and characterisation of photosensitiser-­incorporated polymeric microparticles

Specifically, their ability to reduce the bacterial bioburden of solutions, with low visible light illumination, was studied. An oscillatory ball milling process was employed to mechanically break down a range of synthesised acrylate-based monoliths to produce microparticles of varying sizes, providing large available surface areas for complementary PS incorporation.

Cationic PSs, toluidine blue O (TBO) and tetrakis(4-N-methylpyridyl)porphyrin (TMPyP), were electrostatically incorporated to the anionic polymeric microparticles produced. Conversely, anionic PSs (rose bengal (RB), tetrakis(4-carboxyphenyl)porphyrin (TCPP) and meso-tetra(4- sulfonatophenyl) porphine (TPPS)) were incorporated to cationic polymeric microparticles. The anionic microparticles loaded with a 22 μg/mL TBO solution yielded the most potent, minimal leaching PS-incorporated microparticles, achieving 99.9999% reductions of both Gram-negative and Gram-positive microorganisms within 60 minutes of low intensity red-light irradiation.