•Novel AuNPs functionalized reduced graphene oxide chemiresistive sensor.•Binding of DTT-AuNPs induced by Cr(VI) ion contributed to the sensor response.•Sensitive and selective detection of Cr(VI) ion in water samples.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.Download high-res image (124KB)Download full-size image

Bisphenol A (BPA) is an important endocrine disrupter in environments, for which sensitive and selective detection methods are highly necessary to carry out its recognition and quantification. Here a novel electrochemical sensor was developed based on molecularly imprinted polypyrrole/graphene quantum dots (MIPPy/GQDs) composite for the detection of bisphenol A (BPA) in water samples. A MIPPy/GQDs composite layer was prepared by the electropolymerization of pyrrole on a glassy carbon electrode with BPA as a template. The MIPPy/GQDs composite could specifically recognize BPA in aqueous solutions, which resulted in the decrease of peak currents of K3[Fe(CN)6] at the MIPPy/GQDs) modified electrode in cyclic voltammetry (CV) and differential pulse voltammetry (DPV). There was a linear relationship between BPA concentrations ranging from 0.1 μM to 50 μM and the response value (ΔIDPV) in DPV, with a limit of detection of 0.04 μM (S/N = 3). The sensor was applied for the detection of BPA in tap and sea water samples, with recoveries of 94.5% and 93.7%, respectively. The proposed method provides a powerful tool for rapid and sensitive detection of BPA in environmental samples.

Microcystin-LR (MCLR) is one of the most commonly detected and toxic cyclic heptapeptide cyanotoxins released by cyanobacterial blooms in surface waters, for which sensitive and specific detection methods are necessary to carry out its recognition and quantification. Here, we present a single-walled carbon nanotube (SWCNTs)-based label-free chemiresistive immunosensor for highly sensitive and specific detection of MCLR in different source waters. MCLR was initially immobilized on SWCNTs modified interdigitated electrode, followed by incubation with monoclonal anti-MCLR antibody. The competitive binding of MCLR in sample solutions induced departure of the antibody from the antibody–antigen complexes formed on SWCNTs, resulting in change in the conductivity between source and drain of the sensor. The displacement assay greatly improved the sensitivity of the sensor compared with direct immunoassay on the same device. The immunosensor exhibited a wide linear response to log value of MCLR concentration ranging from 1 to 1000 ng/L, with a detection limit of 0.6 ng/L. This method showed good reproducibility, stability and recovery. The proposed method provides a powerful tool for rapid and sensitive monitoring of MCLR in environmental samples.

Detection of metal ions in living cells is significant in environmental monitoring and health risk assessment. This paper reports a simple and facile method for the detection of Hg2+ ions in Hela cells through fluorescence imaging, which was based on the fluorescence quenching in thymine-rich DNA modified graphene quantum dots (DNA-GQDs) in the presence of Hg2+. The decrease in the fluorescence intensity was attributed to the electron transfer of DNA-GQDs due to Hg2+ bound to the thymine bases of the DNA, resulting in a T–T mismatch hairpin structure. The method shows high selectivity and sensitivity. This present sensing platform will have broad applications in biological imaging and environmental monitoring.

•Molecularly imprinted polymer/mesoporous carbon composite nanoparticles were prepared by precipitation polymerization.•The nanoparticles were used as electrode sensing material with good electrochemical performance.•Selective detection of ofloxacin in aqueous solutions was completed by the electrode material.Molecularly imprinted polymer/mesoporous carbon composite nanoparticles (MCNs@MIP) were prepared through covalent grafting of the polymer onto the surface of mesoporous carbon nanoparticles by precipitation polymerization using ofloxacin as a template. The MCNs@MIP were well monodisperse, with a diameter of ~220 nm. Using the MCNs@MIP as electrode sensing material, the electrode showed good electrochemical activity and selective response to ofloxacin in aqueous solutions. There was a linear relationship between the peak currents in cyclic voltammetry measurement and ofloxacin concentrations in the range of 0.5–100 μM, with a limit of detection (S/N=3) of 80 nM.

Proteomic analysis allows detection of changes of proteins expression in organisms exposed to environmental pollutants, leading to the discovery of biomarkers of exposure and understanding of the action mechanism of toxicity. In the present study, we applied iTRAQ labeling quantitative proteomic technology for global characterization of the liver proteome in mice exposed to perfluorooctane sulfonate (PFOS). This successfully identified and quantified 1038 unique proteins. Seventy-one proteins showed a significant expression change in the treated groups (1.0, 2.5, 5.0 mg/kg of body weight) compared with the control group, and 16 proteins displayed strong dose-dependent changes. Gene ontology analysis showed that these differential proteins were significantly enriched and mainly involved in lipid metabolism, transport, biosynthetic processes, and response to stimulus. We detected significantly increased expression levels of enzymes regulating peroxisomal β-oxidation—including long-chain acyl-CoA synthetase, acyl-CoA oxidase 1, bifunctional enzyme, and 3-ketoacyl-CoA thiolase A. PFOS also significantly induced cytochrome P450s and glutathione S-transferases that are responsible for the metabolism of xenobiotic compounds. The expressions of several proteins with important biological functions–such as cysteine sulfinic acid decarboxylase, aldehyde dehydrogenase, and apolipoprotein A-I, also correlated with PFOS exposure. Together, the present results provide insight into the molecular mechanism and biomarkers for PFOS-induced effects.