CHITOSAN-PORPHYRIN COMPOSITE (CPC) AS PHOTOSENSITIZER IN ANTIBACTERIAL PHOTODYNAMIC THERAPY FOR THE MANAGEMENT OF CHRONIC WOUNDS

Abstract

A promising method to prevent and control infections is Antimicrobial Photodynamic Therapy (APDT). This study investigated the use of chitosan-porphyrin composite (CPC) as photosensitizer for APDT test against four wound bacterial isolates: Staphylococcus aureus, Klebsiella pneumonia, Proteus mirabilis, and Escherichia coli. The chitosan extracted from fresh prawns and porphyrins with different functional groups complexed with zinc, tin, and silver were used. The functional groups on the porphyrin were 4-phenyl (TPP), 4-sulphonatophenyl (TPPS), 4-hydroxylphenyl (THPP), 4-carboxylphenyl (TCPP), 4- methoxylphenyl (TMPP), 4-methyl-4-pyridyl (TMPyP). The CPCs were characterized using UV-Vis and Infra-red spectroscopic techniques and the results confirmed weak interactions between the chitosan and porphyrin molecules and in some cases resulting in aggregation of the porphyrin molecules. A screening study was conducted to investigate both the dark toxicity and photo-toxicity of the composites using agar well diffusion method. The composites that displayed growth inhibition against all pathogens underwent additional evaluation to determine their minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and killing rates. The study found that only silver meso-tetra(4-methoxylphenyl)porphyrin-chitosan composite (CAgTMPP) and silver meso-tetra(4-hydroxylphenyl)porphyrin-chitosan composite (C-AgTHPP) among the twenty-eight CPCs showed activity against all the pathogens, with MBC values as low as 1.25 ug/mL and eradicating the pathogens within 24 hours of exposure to light.