The development of a biotin-guided and mitochondria-targeting fluorescent probe for detecting SO2 precisely in cancer cells

Abstract

Mitochondrial sulfur dioxide (SO2) is very closely associated with various activities of cancer cell. However, the specific physiological and pathological roles of mitochondrial SO2 in cancer cells are still not well defined. Lacking a powerful molecular tool for detecting mitochondrial SO2 in cancer cells precisely is an essential factor. So it is urgent to develop a specific method for monitoring mitochondrial SO2 in cancer cells. Herein, we described a distinct cancer cell-specific fluorescent probe NS for detecting mitochondrial SO2 accurately in cancer cells. Biotin, possessing of high affinity for cancer cells, was decorated into probe to provide its cancer cell-targeting property. Moreover, the positive charge hemicyanine group was used to anchor mitochondria selectively. A series of spectral results from concentration titration, dynamics and selectivity experiments showed that NS had high sensitivity, fast response and high selectivity to SO2. These properties render NS ability for detecting SO2 in living cells. In biological imaging, the achievements in detecting exogenous and endogenous SO2 displayed the probe had favorable response to SO2 in living cells with well biocompatibility. Significantly, assisted by competitive experiments with excess biotin, NS demonstrated distinct cancer cell-targeting for detecting mitochondrial SO2. Furthermore, NS could locate mitochondria specially and detect mitochondrial SO2 in cancer cells by co-localization. Moreover, NS can trace SO2 in zebrafish with long wavelength emission. Therefore, NS can achieve in tracing mitochondrial SO2 selectively in cancer cells. It would be a powerful tool for well defining the physiological and pathological roles of mitochondrial SO2 in cancer cells.