A new H₂S-specific near-infrared fluorescence-enhanced probe that can visualize the H₂S level in colorectal cancer cells in mice

Abstract

Near-infrared (NIR) fluorescence-based sensors capable of selective detection of H₂S <i>in vivo</i> would be useful tools to understand the mechanisms of diseases. A new NIR fluorescence probe <b>1</b> was developed for the detection of endogenous H₂S in colorectal cancer cells in mice. <b>1</b> displayed an 87-fold fluorescence enhancement at 796 nm (with excitation at 730 nm) when reacted with H₂S in a buffer (pH 7.4). <b>1</b> was water-soluble, cell-membrane-permeable, had low cytotoxicity and high selectivity and sensitivity for H₂S. The properties of <b>1</b> enable its use in monitoring endogenous H₂S in living cells, tissues, and mice. The bioimaging results indicated that (1) d-Cys could induce endogenous H₂S production in living cells and stimulate angiogenesis; (2) tail intravenous injection of <b>1</b> into mice generated strong fluorescence in the liver while intraperitoneal injection of d-Cys could further enhance fluorescence in the liver <i>in vivo</i>; (3) importantly, endogenous H₂S in colorectal cancer cells (HCT116, HT29) <i>in vitro</i> and in murine tumor models could be quickly and selectively detected by intratumoral injection of <b>1</b>. These results indicated that our new probe could serve as an efficient tool for the detection of cellular H₂S in living animals and even for cancer diagnosis.