Real-time monitoring of endogenous cysteine levels in living cells using a CD-based ratiometric fluorescent nanoprobe

Hong Wang, Peisheng Zhang*,Yong Tian,Yuan Zhang,Heping Yang,Shu Chen,Rongjin Zeng*,Yunfei Long and Jian Chen*

A simple and readily available fluorescent probe is needed for the real-time monitoring of endogenous cysteine (Cys) levels in living cells, as such a probe could be used to study the role of Cys in related diseases. Herein, we report the first fluorescent probe based on carbon dots (CDs-FITA) for the selective and ratiometric imaging of endogenous Cys in live cells. In this ratiometric fluorescent probe, a fluorescein derivative (FITA) that recognizes Cys is covalently linked to the surfaces of carbon dots (CDs); employing CDs greatly improves the water solubility of the probe. Acrylate on FITA is selectively cleaved by Cys in aqueous solution under mild conditions, leading to a dramatic increase in the fluorescence from fluorescein. The probe therefore allows the highly selective ratiometric fluorescent detection of Cys even in the presence of various interferents. The as-prepared CDsFITA showed excellent performance when applied to detect Cys in blood serum. In addition, due to its negligible cytotoxicity, the CDs-FITA can also be utilized for the real-time monitoring of endogenous cysteine (Cys) levels in living cells.

https://link.springer.com/article/10.1007/s00216-018-1091-x

Analytical and Bioanalytical Chemistry 2018, doi.org/10.1007/s00216-018-1091-x)c