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.