Mechanosensitive fluorescent probes for practical use in biology: towards more sensitive and precisely localized membrane tension reporters

In 2016, Flipper-TR® has been introduced as the first small fluorescent molecule capable of visualizing membrane tension changes in living cells. In the presented thesis, modifications of this molecule have been performed in order to a) improve its mechanosensitivity and spectroscopic properties and b) enable its specific localization to desired cellular sites. Unprecedented mechanosensitivity has been achieved by increasing the twist and the push-pull strength of the molecule. This came, however, at a cost of decreased chemical stability. To address this problem, the concept of “cascade switches” has been introduced and investigated. Furthermore, various targeting strategies have been explored. Among them combining flippers with protein tag technologies proved to be particularly successful. The resulting universally targetable “HaloFlippers” and “BioFlippers” can visualize both lipid order and membrane tension changes selectively in many cellular organelles