Novel bioorthogonal click-to-release systems for fluorogenic proximity labelling Dora Kern 1,2 Attila Kormos, 1 Allegra Lövei, 1 Ágnes Szatmári, 1 Péter Kele 1 1 ELKH Research Centre for Natural Sciences, Hungary 2 Eötvös Loránd University, Hungary Light is a ubiquitous tool used in many disciplines from classical optics to biomedical applications, such as fluorescent imaging and photodynamic therapy (PDT). The latter two requires small molecule probes attached selectively to the target. Tetrazine quenched dyes are promising candidates due to their fluorogenicity and bioorthogonality. However, the modulation effect exerted by the tetrazine declines towards the biologically more relevant red end of the spectrum. The goal of the present research is the synthesis of bioorthogonally applicable efficiently modulated probes suitable for labelling intracellular proteins and subsequent super resolution microscopy imaging, photodynamic therapy or photoactivated chemotherapy. We aim to address this problem by combining a click-to-release type tetrazine, a masked quinone methide and push-pull dyes having a phenolate as the donor moiety. The tetrazine functions as the specific targeting element and the trigger of release (modulation) at the same time. The quinone methide that forms in a reaction cascade triggered by the tetrazine’s click reaction reacts with nucleophilic amino acid side chains resulting in covalent labelling. Such covalent ligation of the dye core transforms it into its photoresponsive form. This mechanism is proposed to be used in the targeted ligation-based activation of fluorogenic probes, photosensitizers or photolabile linkers (photocages) for imaging, and therapeutic applications. In order to investigate the basics of our concept we synthesized several coumarins, in which the tetrazine motif was connected either with a self-immolative linker or directly to the dye core. We also compared the click-to- release reaction and the subsequent quinone methide formation of the probes.
P20
© The Author(s), 2023
Made with FlippingBook Learn more on our blog