Naked-eye trackable fluorescence-enhanced probe for real-time imaging of biological thiols in living cells.

Biothiols, comprising cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), constitute the predominant thiol pool in biological systems and serve as critical regulators of redox homeostasis. Despite their physiological significance, these species exhibit marked susceptibility to oxidative stress, with resultant concentration dysregulations being implicated in the pathogenesis of various disorders including neoplastic progression, cardiovascular abnormalities, and neurodegenerative conditions. To address the critical need for reliable biothiols monitoring in living systems, we present a rationally engineered hemicyanine-based fluorescent probe (MCY-NB) employing a turn-on fluorescence mechanism. The proposed probe possesses excellent fluorescence properties, biocompatibility, and ease of operation, making it an essential prerequisite for its application in biological systems. Compared with other reports, this study is capable of quantitatively detecting total biothiols to meet the clinical demand for biothiols monitoring in samples. Furthermore, the fluorescent probe can selectively detect total biothiols against a series of amino acids with a broad concentration range (1-250 μM). Moreover, the successful realization of naked-eye visualization of biothiols through this strategy provides a highly attractive alternative for portable outdoor detection. Most critically, the fluorescence probe can realize the dynamic monitoring of intracellular biothiols fluxes through its permeability, which holds potential for application in the diagnosis of diseases associated with biothiols imbalances.