A Dual‐Emission Probe for Discriminating Cys/Hcy from GSH/H 2 S in Human Blood Serum and Live Cells

Abstract Cysteine (Cys), homocysteine (Hcy), glutathione (GSH), and hydrogen sulfide (H 2 S) are very important in maintaining the equilibrium between reduction and oxidation processes in biological systems. However, the development of an advanced technique for the selective and specific detection of these thiols continues to pose a significant challenge. In this study, we developed a light up fluorescence sensor (BDYF‐NBD) derived from boron dipyrromethene (bodipy), conjugated with nitrobenzoxadiazole (NBD). BDYF‐NBD is a far‐red fluorescent probe that operates with a single excitation wavelength (470 nm) and utilizes two distinct fluorescence channels for the differentiation of GSH/H 2 S and Cys/Hcy. Upon excitation at 470 nm, BDYF‐NBD exhibits very weak fluorescence but generates distinct green fluorescence at 550 nm for Cys/Hcy and far‐red fluorescence at 630 nm in the presence of GSH/H 2 S. The limit of detection (LOD) was measured to be 17 nM for Cys, 68 nM for GSH, 43 nM for Hcy, and 14 nM for H 2 S. Furthermore, BDYF‐NBD successfully visualized and differentiated GSH/H 2 S from Cys/Hcy in human blood serum sample and live cancer cells through green and far‐red fluorescence, demonstrating its potential for real time, selective thiol detection.