Fluorescence lifetime measurements of disulfonated aluminium phthalocyanine in the presence of microbial cells

The fluorescence lifetimes of disulfonated aluminium phthalocyanine (AlPcS2) ill the presence of several different microbial cells are measured using the technique of time correlated Single Photon Counting (TCSPC) employing front-face illumination. The microbes Studied are: Escherichia coli, Porphyromonas gingivalis (Gram-negative bacteria). Streptococcus mutans (a Gram-positive bacterium). and the yeast Candida albicans. Complex fluorescence decays are observed when AlPcS2 is in the presence of these microbes: the fluorescence decay data can be fitted to it distribution of exponential lifetimes indicating that the AIPcS(2) molecules experience a range of micro-environments. The average fluorescence lifetimes of AlPcS2 in the presence of the microbes Studied range from 4.85 to 5.95 ns, indicating differences in the cellular localisation of AlPcS2 with each of the microbes studied. These novel data are presented alongside. brief summary of existing AIPcS(2) fluorescence lifetime data measured both in solution and ill model biological systems.