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Divalent mercuric (Hg) ion is one of the most prevalent forms of mercury species in waters with high toxicity and bioaccumulation in the human body, for which sensitive and selective detection methods are highly necessary to carry out its recognition and quantification. Here an electrochemically reduced graphene oxide (RGO) based chemiresistive sensor was constructed and used for the detection of Hg ion in various water samples. Monolayer GO sheets were assembled onto interdigitated electrodes, followed by reduction through linear sweep voltammetry and then modification with a single-stranded DNA aptamer. The electrochemically derived RGO based sensor showed selective response to as low as 0.5nMHg ion in presence of other metal ions and matrices. A comparison between chemiresistive sensors prepared with electrochemically and chemically derived RGO showed that the former had better response performance for sensing Hg ion. The proposed method provides a simple tool for rapid, selective and sensitive monitoring of Hg ion in environmental samples.

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A facile method for detection of Hg2+in living cells based on DNA modified graphene quantum dots.

Detection of highly toxic Cr(VI) is greatly desired. In the present study, a highly sensitive method for Cr(VI) detection by reduced graphene oxide (rGO) chemiresistor and 1,4-dithiothreitol (DTT) functionalized Au nanoparticles (AuNPs) is reported. The detection strategy is based on the selective binding between DTT functionalized AuNPs1 located in rGO conductive channels and DTT functionalized AuNPs2 in solution through the formation of disulfides induced by Cr(VI) at acidic condition, which results in aggregation of DTT functionalized AuNPs2 on the rGO channels producing a readily measurable resistance change. The response of the chemiresistor is rapid and allows real-time monitoring of Cr(VI).Using this method, as low as 0.9 nM of Cr(VI) in water was detected with good selectivity.The proposed method has great potentials for monitoring of trace Cr(VI) in drinking water.