Development of a red fluorescent light-up probe for highly selective and sensitive detection of vicinal dithiol-containing proteins in living cells

Abstract

Vicinal dithiol-containing proteins (VDPs) play a key role in cellular redox homeostasis and are responsible for many diseases. Here, we develop a red fluorescent light-up probe <b>FAsH</b> for the highly selective and sensitive detection of VDPs using the environment-sensitive 2-(4-dimethylaminophenyl)-4-(2-carboxyphenyl)-7-diethylamino-1-benzopyrylium (<b>F1</b>) as the fluorescent reporter and cyclic dithiaarsane as the targeting unit. <b>FAsH</b> is almost nonfluorescent in aqueous solution. However, it exhibits intense fluorescence emission upon binding to reduced bovine serum albumin (rBSA, selected as the model protein). The fluorescence intensity of <b>FAsH</b> is directly proportional to the concentration of rBSA over the range of 0.06-0.9 μM, with a detection limit (3<i>δ</i>) of 0.015 μM. Importantly, the fast kinetics of binding between <b>FAsH</b> and VDPs (∼2.5 min) enables the dynamic tracing of VDPs in biological systems. Preliminary experiments show that <b>FAsH</b> can be used for the no-wash imaging of endogenous VDPs in living cells. In addition, our study shows that <b>F1</b> presents both high environment-sensitivity and good fluorescence properties, and is promising for the development of no-wash fluorescent light-up probes for target-specific proteins in living cells.