Time- and space-correlated single-photon counting system for fluorescence microspectroscopy of biological specimens

It is well known that fluorescence microspectroscopy is a powerful tool in the study of biological objects. Fluorescence lifetime imaging is one of the modern and promising techniques applied in these studies. The method implies the detection of not only spectral parameters of some molecules and molecular structures but also the fluorescence lifetimes. Thus, one can easily distinguish between two fluorophores with similar spectral properties but having different fluorescence lifetimes. Additional possibilities are offered by the method for stray light rejection and detection of Raman scattering because of the difference in time-correlation of the excitation, fluorescence, and Raman photons. We suggest the application of an original position-sensitive micro-channel plate photomultiplier as a key element of a newly developed fluorescence microspectrometer designated for the study of biological objects (cells, subcellular structures and organells). We present the first results of the experiments with the test objects. The results obtained clearly show that the new system is rather promising in the studies of living cells and tissues.