Fibrinogen-templated gold nanoclusters for fluorometric determination of cysteine and mercury(II).

Gold nanoclusters (Au NCs) using fibrinogen (FBG) protein as template are fabricated via one-pot reduction strategy, and applied for fluorometric detections of cysteine (Cys) and mercury(II). The modified FBG-Au NCs exhibit red fluorescence, with excitation/emission maxima at 360/620 nm, a 7% quantum yield, and a 2.2 µs decay time. The fluorescence of the nanoprobe is quenched by Cys and Hg(II). Cys can be determined by fluorometry in the 0.01 to 150 µmol L-1 concentration range and with a detection limit of 0.79 µmol L-1. Due to the oxidation of Hg(II), it can be detected in the 0.01 to 10 µmol L-1 concentration range. The properties of the FBG-Au NCs and the analytical performance are comparable with previously reported peptide/protein-templated Au NCs, supplying a promising candidate for Au NCs nanoprobes synthesis and applications. Graphical abstractSchematic representation of the preparation of gold nanoclusters (Au NCs) using fibrinogen (FBG) as the template. The modified Au NCs were applied to the fluorometric detection of cysteine (Cys) and mercury ion (Hg(II)).