DNA-Mediated Graphene Oxide/Platinum Nanozymes for Label-Free Colorimetric Detection of Hg2+

Mercuryions (Hg2+) have persistent bioaccumulationand high toxicity, which can severely damage the ecological systemand human health. Therefore, sensitive methods are required for Hg2+ analysis. Herein, a DNA-mediated growth strategy was developedfor the synthesis of platinum nanoparticles (PtNPs) on the surfaceof graphene oxide (GO). The resulting GO-DNA-PtNPs displayed excellentperoxidase-mimicking activity in a sequence-dependent manner. Theperoxidase-mimicking activity could be significantly inhibited byHg(2+) because of the specific trapping of Hg2+ by thymine bases (T-Hg2+-T) and in situreduction of Hg2+ by PtNPs on the GO surface. Under optimalconditions, there was a good linear range from 1 pM to 1 & mu;Mwith a detection limit of 2.2 pM for Hg2+ analysis. Thissensor demonstrated excellent analytical performance for assessingHg(2+) in complex lake waters. This work provides an effectivestrategy for the preparation of PtNP-based nanozymes and broadensthe applications of PtNPs for biosensing.

Automated summary

A DNA-mediated growth strategy was developed in this study for the synthesis of platinum nanoparticles (PtNPs) on the surface of graphene oxide (GO). The resulting GO-DNA-PtNPs exhibited excellent peroxidase-mimicking activity, and the activity could be inhibited by Hg(2+) due to the specific trapping of Hg2+ by thymine bases (T-Hg2+-T) and in situ reduction of Hg2+ by PtNPs on the GO surface. The sensor showed good linear range (from 1 pM to 1 μM) and a detection limit of 2.2 pM for Hg2+ analysis, demonstrating excellent analytical performance in complex lake waters.