A turn-on fluorescent sensor for cysteine based on BODIPY functionalized Au nanoparticles and its application in living cell imaging.

BODIPY functionalized Au nanoparticles (PyBDP-AuNPs) have been developed for detecting cysteine. Gold nanoparticles were prepared by reducing HAuCl 4 with sodium citrate, using PyBDP as the capping agent. Upon addition of cysteine, PyBDP molecules are liberated from the AuNP surface through ligand-exchange displacement based on the strong affinity of Au with the thiol group and result in green fluorescence from PyBDP molecules. This cysteine-induced displacement of PyBDP-AuNPs was monitored by fluorescent spectroscopy with a detection limit of 1.2 μM. Optimal detection of cysteine was achieved over a pH range from 5 to 12. In addition, PyBDP-AuNPs can be used as a fluorescent probe for detecting cysteine in living cells. [ABSTRACT FROM AUTHOR]