13 October 2006 Stroboscopic technique for measurement of fluorescence lifetimes of bacteria and biological interferents
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Time-resolved fluorescence was measured for 25 biological species of vegetative bacteria, spores, fungi and pollens using stroboscopic technique and UV LEDs (280 and 340 nm) as a source of excitation. For all the examined species, the fluorescence lifetime was described by double exponential kinetics. With excitation at 280 nm, the decay time of the slow component varies from 2.0 to 4.6 ns. The fast component varies from 0.4 to 1.1 ns and its relative amplitude is greater than measured in tryptophan solution, which is a result of strong fluorescence quenching. For excitation at 340 nm, the lifetimes of fluorescence components are 3-9 ns and 0.4-1.9 ns, respectively. Higher differences in decay times are observed for other groups, especially pollens, that is connected with higher number of fluorophores in this spectral range. In general, lifetimes and relative fractional contributions of components are various for particular biological species, however, they are not specific for one group, what causes difficulties in BWA classification with time-resolved fluorescence method. Evaluation of the decay curves using PCA method shows low similarity of species in groups of living bacteria and spores and strong influence of interferents is observed.
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M. Wlodarski, M. Wlodarski, K. Kwasny, K. Kwasny, K. Kopczynski, K. Kopczynski, } "Stroboscopic technique for measurement of fluorescence lifetimes of bacteria and biological interferents", Proc. SPIE 6398, Optically Based Biological and Chemical Detection for Defence III, 63980L (13 October 2006); doi: 10.1117/12.687865; https://doi.org/10.1117/12.687865

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