Development and characterisation of photosensitiser-­incorporated polymeric microparticles

Student thesis: Doctoral ThesisDoctor of Philosophy


This thesis details the production and characterisation of a range of photosensitiser (PS)- incorporated polymeric microparticles, optimising the photodynamic antibacterial activity exerted. 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. Overall, the broad-spectrum activity of photodynamic antimicrobial chemotherapy measures, and the unlikely development of microbial resistance reported, the potential for these PS- incorporated microparticles is encouraging.
Date of AwardDec 2020
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy
SupervisorNicola Irwin (Supervisor) & Colin McCoy (Supervisor)


  • Photosensitisers
  • photodynamic antimicrobial chemotherapy
  • polymeric microparticles
  • ball milling
  • antimicrobial

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