4195231 - Photodynamic inactivation (PDI) of microorganisms with copper meso–pyridyl porphyrin isomers | Poster Board #330

Photodynamic Inactivation (PDI) is an antimicrobial approach, independent of antibiotic resistance, that targets pathogens utilizing light and photosensitizers in the presence of oxygen. The growing international concern for the rise in drug-resistant microorganisms has driven research to determine approaches that will keep microbes from developing further immunological adaptations. Photosensitizers are molecules activated by light that produce reactive oxygen species (ROS) lysing and causing cell death in structures of microbes and in diseased mammalian cells. The photosensitizers applied in this experiment are meso–Tetra(N–methyl–pyridyl)porphine tetrachloride isomers. Three variations of the nitrogen placement were used to understand the interactions with the bacterial cell wall of Escherichia coli, both in their freebase and copper metallated form. These compounds were selected for their reactivity, allowing for multiple interactions to be observed between each porphyrin and the gram-negative E. coli. Minimum inhibitory concentration (MIC) tests were conducted to determine the concentration at which each porphyrin will work most efficiently in eliminating microorganisms. Fluorescent light was additionally employed to activate the six different porphyrin isomers using varying intensities. Changes in the emission intensities and wavelength shifts will be observed to determine if a particular light intensity enhances the activation process. A computational analysis was performed using B3LYP/6-31G(d) and molecular orbital maps were created to correlate with the formation of singlet oxygen. In determining its efficiency, the primary objective of this experiment is to advance photodynamic inactivation techniques to be applied to microorganisms eliminating any form of resistance.