A colorimetric and red emissive fluorescent probe for cysteine and its application in bioimaging

Developing effective methods to detect and image Cys in vivo has become an increasingly important area of research. In this work, two colorimetric and fluorescent sensors 1 and 2 were presented for detecting Cys with different reactive rates in an intramolecular cyclization reaction between acrylate and thiols. Probe 2 is the isomer of the probe 1, which has greater steric hindrance than probe 1. The performed reaction kinetics experiments showed that the reaction rates of 1 with thiols were far more rapid than those of 2 with thiols. From the observed crystal structures of these two compounds, we speculate that the larger steric hindrance around the acrylate group in probe 2 outweighs the electronic effect, thus slowing down the reaction between the acrylate and thiols. Probe 1 was successfully applied with negligible cell toxicity toward the imaging of biothiols in living cells and zebrafish.

Graphical abstractThe effects of electron and steric hindrance on the reactivity of the two colorimetric and fluorescent sensors toward thiols were investigated. Meanwhile, probe 1 could be successfully applied in imaging of biothiols in living cells and zebrafish with neglectable cell toxicity.Figure optionsDownload full-size imageDownload as PowerPoint slide