EXPLORATION AND DEVELOPMENT OF XYLOPYRINDE FLUORESCENT TOOLS FOR SPATIOTEMPORAL IMAGING

Xylopyridine (affectionately referred to as Xylo), represents a class of small molecule fluorescent dyes known for their ability to irreversibly convert their spectral properties upon irradiation with UV light. This quality, known as photoconvertibility, belongs to a series of mechanisms we describe as photorespsonsive (PR) fluorescence. Photoactivatability and photoswitchability represent two other possible mechanisms of photoresponsive fluorescence. Photoresponsive fluorescent proteins (PRFPs) have enabled a variety of dynamic imaging applications including spatiotemporal tracking of cells, organelles, and proteins of interest. However, they are limited by their large size, poor photostability, and propensity to oligomerize. Photoresponsive small molecules (PRSMs) hold the promise of greatly improving the future of fluorescence microscopy by addressing these issues and have already enabled markedly improved performance for spatiotemporal and sub diffraction limit imaging of cells, cellular structures, and biomolecules. This thesis will describe the development and exploration of the Xylopyridine scaffold as a PRSM platform capable of improving the spatiotemporal imaging of crowded biological systems. An improved synthetic strategy for accessing the Xylo core will be described followed by rapid diversification facilitated by its ease of access. Novel photoconvertible molecules based on the Xylopyridine scaffold will then be evaluated for their spatiotemporal imaging performance. Finally, spatiotemporal imaging of cholesterol within living cells will be discussed to showcase the paradigm shifting capability of Xylopyridine fluorescent tools.