Glutathione-stabilized Gold Nanoclusters Research Articles

A fluorescent switch sensor for detection of anticancer drug and ctDNA based on the glutathione stabilized gold nanoclusters

A facile and sensitive fluorescence switch sensor for the detection of both anticancer drug and calf thymus DNA (ctDNA) was developed based on glutathione stabilized gold nanoclusters by using mitoxantrone as both the fluorescence quencher to gold nanoclusters and the intercalating agent to ctDNA. The fluorescence of gold nanoclusters can be effectively quenched by MTX because of the absorption of MTX on the surface of gold nanoclusters and the subsequent occurring photoinduced electron transfer process from gold nanoclusters to MTX. As for possessing large conjugated system, MTX intercalates into the groove of duplex helix DNA. And the process efficiently promotes the separation of MTX from the surface of gold nanoclusters, which induces the enhanced fluorescence signal of the sensor. The fluorescence quenching effect was mainly concentration dependent, which was used to determine anticancer drug MTX. The fluorescent response of MTX detection was in the linear range from 0.1μM to 6μM with the detection limit of 20nM. The restored fluorescence intensity was directly proportional to the concentration of ctDNA in the range of 0.5–8μg/mL and a low detection limit of 0.1μg/mL. The proposed method was applied for the detection of ctDNA in real samples with satisfactory results.

Facile preparation of glutathione-stabilized gold nanoclusters for selective determination of chromium (III) and chromium (VI) in environmental water samples

A novel method for selective determination of Cr(III) and Cr(VI) in environmental water samples was developed based on target-induced fluorescence quenching of glutathione-stabilized gold nanoclusters (GSH-Au NCs). Fluorescent GSH-Au NCs were synthesized by a one-step approach employing GSH as reducing/protecting reagent. It was found that Cr(III) and Cr(VI) showed pH-dependent fluorescence quenching capabilities for GSH-Au NCs, and thus selective determination of Cr(III) and Cr(VI) could be achieved at different pHs. Addition of EDTA was able to effectively eliminate the interferences from other metal ions, leading to a good selectivity for this method. Under optimized conditions, Cr(III) showed a linear range of 25–3800μgL−1 and a limit of detection (LOD) of 2.5μgL−1. The Cr(VI) ion demonstrated a linear range of 5–500μgL−1 and LOD of 0.5μgL−1. The run-to-run relative standard deviations (n=5) for Cr(III) and Cr(VI) were 3.9% and 2.8%, respectively. The recoveries of Cr(III) and Cr(VI) in environmental water samples were also satisfactory (76.3–116%). This method, with its simplicity, low cost, high selectivity and sensitivity, could be used as a promising tool for chromium analysis in environmental water samples.