Emission Ratiometric Imaging of Intracellular Zinc: Design of a Benzoxazole Fluorescent Sensor and Its Application in Two-Photon Microscopy

摘要

The inorganic physiology of intracellular zinc is poorly understood but of emerging importance in understanding a variety of disorders in humans. Histochemical studies of mammalian tissues including prostate, insulin secreting pancreatic islets, and granule neurons of the hippocampus reveal patterns of Zn(II) accumulation that are disrupted in some types of prostate cancer, diabetes, and neurodegenerative disorders, respectively. The function of zinc in these tissues or even within single-cell organisms such as S. cerevisiae remains controversial. Confocal fluorescence microscopy has proved to be a central tool in understanding calcium biology and has the potential to resolve these issues in zinc biology. Two-photon excitation (TPE) fluorescence microscopy provides significant advantages over standard laser confocal approaches by providing deeper sectioning, less phototoxicity, and selective excitation of a smaller focal volume (i.e., femtoliter), thus decreasing background fluorescence. Such advances can be applied to zinc physiology; however, this requires the parallel development of new zinc-specific chemical probes that operate within cells.