MPI Campus Seminar: Enhancing the biocompatibility of rhodamine fluorescent probes by positional isomerism approach

Imaging of cellular structures and biomolecules in living cells with high spatial resolution is fundamental for understanding biological processes. Nowadays the sub-diffraction resolution can be achieved by a number of super-resolution microscopy (SRM) methods. The common feature of the different approaches is to switch fluorophores between a fluorescent “on” and a dark “off” state, allowing one to collect light from only a subset of precisely localized “on” fluorophores. Technological advancement of SRM methods increased the interest in biocompatible fluorescent probes specifically designed for imaging of living samples. Such probes based on synthetic fluorescent dyes are ideally suited for SRM methods due to their small size, tunable photophysical properties and extremely simple staining protocols. Stimulated emission depletion microscopy (STED) compatible rhodamine class fluorescent dyes are exclusively suited for the development of fluorescent probes for live-cell imaging. Certain structural features of rhodamine dyes allows the attachment of the targeting moiety at different positions – a feature which was overlooked before, which gives the opportunity to optimize the performance of the fluorescent probes in a novel manner. Tuning of rhodamine dyes based probes by structural isomerism approach led to the discovery of, to the best of our knowledge, the most efficient probes for tubulin, actin and DNA labelling in living cells.