Factors affecting the uncaging efficiency of 500 nm light-activatable BODIPY caging group.

Photoremovable protective groups, or caging groups, enable us to regulate the activities of bioactive molecules in living cells upon photoirradiation. Nevertheless, requirement of UV light for activating caging group is a significant limitation due to its cell toxicity and its poor tissue penetration. Our group previously reported a 500 nm light-activatable caging group based on BODIPY scaffold, however, its uncaging efficiency was lower than those of conventional caging groups. Here we show that the uncaging quantum yield (QY) of BODIPY caging group depends upon the driving force of photo-induced electron transfer (PeT). We also found that the uncaging QY increased in less polar solvents. We applied these findings to develop BODIPY-caged capsaicin, which is well localized to low-polarity intracellular compartments, as a tool to stimulate TRPV1 in live cells in response to blue-green light.