One-pot fabrication of amino acid and peptide stabilized gold nanoclusters for the measurement of the lead in plasma samples using chemically modified cellulose paper

The ultra-small size, excellent photo-stability, and tremendous fluorescence properties make the gold nanoclusters (AuNCs) as novel chemo- and biosensors. Herein, a one-pot approach was implemented for fabricating highly fluorescent AuNCs using histidine (His) and glutathione (GSH) as a reducing and protecting agent. Assynthesized GSH-AuNCs@His exhibits bright green fluorescence with excitation and emission peak of 420 and 502 nm, respectively, with a quantum yield of 7.5 %. The GSH conjugated with law fluorescent AuNCs@His through the free amines of His, and then utilized for the nanomolar detection of Pb2+ ion in aqueous solution via selective fluorescence turn-off mechanism with linear concentration range 5.0 -1000 nM. The detection limit for Pb2+ ion was calculated 1.0 nM, which is much lower than the allowed concentration of Pb2+ ion in drinking water. The synthesized GSH-AuNCs@His was applied to Pb2+ ion within the spiked plasma sample and obtained excellent recovery with good precision and accuracy. The study also presents chemically modified cellulose paper strips with the conjugated GSH-AuNCs@His for the detection of Pb2+ ion.