A near-infrared self-assembled micellar nanoprobe for highly effective detection of cysteine in vitro and in vivo

As the main substrate participating in various physiological and pathological processes, the abnormal intracellular level of Cysteine (Cys) is closely associated with the occurrence and development of various diseases. Therefore, it is of great importance to establish a sensitive and efficient method for the precise exploration of Cys. Herein, we rationally designed and synthesized a water-soluble fluorescent nanoprobe Nano-PH1 for monitoring Cys in vitro and in vivo. The small molecular probe PH1 with 2,4-dinitrobenzene sulfonate (DNBS) as recognition moiety was constructed based on a phenothiazine derivative. To further improve the water solubility and selectivity of the probe, PH1 was assembled with an amphiphilic copolymer (mPEG-DSPE) to prepare a water-soluble fluorescent nanoprobe Nano-PH1. Fortunately, the nanoprobe preserves the excellent properties of small molecules and performs well in aqueous solution, as well as exhibiting a good selectivity only to Cys. Moreover, Nano-PH1 was successfully used to monitor Cys in living cancer cells and zebrafish larvae. We hope that this novel scaffold will provide a new reference for visualizing Cys in other biological systems.