MANGO-“Fruitcage”: A conditional photocage utilizing a fluorescence light-up aptamer

Photolabile protecting groups (PPGs) offer light-controlled molecular activation, but improving their photolysis quantum yield (QY) remains a challenge. Here, we present a proof of concept for an approach that we call "fruitcaging" which pertains to new conditionally activatable photocages. We show that a photocleavable thiazole orange 1 derivative (TO1-cage) alone has a QY below 0.1%, rendering it nearly inactive. However, in the presence of the fluorescence light-up aptamer (FLAP) Mango, the fluorescence emission increased 180-fold and the photocleavage reaction 14-fold. Femtosecond time resolved experiments revealed a drastically prolonged excited state lifetime of the TO1-cage upon binding to the Mango-aptamer, which facilitates the cleavage reaction and turned an inactive photocage to an active aptamer-photocage system - the “fruitcage”. This strategy offers detailed insights in the engineering of the excited state dynamics of a TO1-based PPG and therefore presents a new tool for efficient conditionally activated PPG for a variety of applications in the field of photochemistry.