Ultrasensitive colorimetric detection of Hg2+ based on glutathione-modified Au nanoflowers

Hg 2+ induces rapid aggregation of glutathione-modified Au nanoflowers (GSH-Au NFs) with activated peroxidase-like activity. • Glutathione modified gold nanoflowers (GSH-Au NFs) have almost no peroxidase-like activity. • Mercury ions (Hg 2+ ) can induce rapid aggregation of GSH-Au NFs. • Hg 2+ -GSH-Au NFs aggregates have high peroxidase-like activity. • Mechanisms behind these phenomena are explored. • A catalytic colorimetric method with high sensitivity and selectivity for Hg 2+ sensing has been established. Due to the harm of metal mercury to the environment and the human body, there is an urgent need for exploring novel, simple, and reliable methods for the detection of Hg 2+ . Herein, a colorimetric method is proposed for the determination of Hg 2+ based on the analyte inducing the aggregation of Glutathione-modified gold nanoflowers (GSH-Au NFs) with activated peroxidase-mimicking activity. Briefly, highly dispersed GSH-Au NFs show negligible enzyme-like activity in water. When Hg 2+ is added, GSH-Au NFs would aggregate rapidly for the interaction of Hg 2+ with the carboxyl and amine groups of GSH. And the aggregates exhibit high peroxidase-mimicking catalytic activity and can catalyze the color reaction of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the presence of H 2 O 2 . Based on these phenomena, an ultrasensitive colorimetric detection method of Hg 2+ has been developed. The linear range of this method is 10–300 nM and the detection limit is down to 3.9 nM, which is much lower than the standard value specified by the US EPA. The accuracy of the method has been verified in water samples, which reveals its great potential in environmental monitoring.