This starter grant award of the Chemistry Division to the University of Texas at Austin supports the research of Professor Jason B. Shear. The theme of the research is ultraviolet fluorescence detection of biological chromophores. The work investigates the mechanisms and extent of multiphoton-excited degradation of monoamine neurotransmitters excited using different numbers of photons of different characteristic wavelengths. Comparisons are made of the photodestruction quantum yields for three-photon excitation of neurotransmitters using a modelocked titanium:sapphire laser in the near-infrared wavelength range, and for two-photon excitation using a frequency doubled titanium:sapphire laser. Sources of background in both two- and three-photon excited fluorescence measurements are evaluated and used in combination with the photodestruction measurements to optimize ultraviolet fluorescence detection of natively fluorescent neurotransmitters analyzed with capillary electrophoresis. The research will advance efforts toward quantitative measurement of neuronal chemistry at the subcellular level. Improved detectability of a variety of natively fluorescent neurotransmitters will provide new capabilities for characterizing fundamental mechanisms of chemical signalling between cells.
