Fa Huanbao

Colorimetric sensing of chromium(VI) ions in aqueous solution based on the leaching of protein-stabled gold nanoparticles

Herein, we developed a simple, sensitive and non-aggregation-based method for the selective colorimetric detection of chromium(VI) ions (Cr(VI)) in an aqueous solution. In the presence of hydrobromic acid (HBr), bovine serum albumin stable gold nanoparticles (BSA-Au NPs) were gradually dissolved by Cr(VI) in the etching process of gold. The leaching of the BSA-Au NPs results in a rapid and remarkable damping of the surface plasmon resonance (SPR) and hence induces a visible color change. This colorimetric strategy based on the etching process of gold provided a highly sensitive and selective detection method toward Cr(VI). Under optimal conditions, the amount-dependent colorimetric response was linearly correlated with Cr(VI) concentrations ranging from 0.15 μM to 50.0 μM, with a detection limit down to 120 nM measured as 3δ. Moreover, the developed cost-effective probe was successfully applied to real river samples, which demonstrated its potential for field applications.

Design of L -Cysteine Functionalized Au@SiO 2 @Fe 3 O 4 /Nitrogen-doped Graphene Nanocomposite and Its Application in Electrochemical Detection of Pb 2+

A novel magnetic electrochemical sensor was designed for determination of lead ions based on gold nanoparticles(AuNPs)@SiO2@Fe3O4/nitrogen-doped graphene(NG) composites functionalized with L-cysteine. The Au@SiO2@Fe3O4/NG was synthesized by the electrostatic adsorption between AuNPs and SiO2-coated Fe3O4 NPs(SiO2@Fe3O4) and the amide bond between Au@SiO2@Fe3O4 and NG. L-Cysteine was successfully functionalized on the surface of Au@SiO2@Fe3O4/NG nanocomposites via the S―Au bond between L-cysteine and AuNPs. Owing to numerous active sites in L-cysteines and high conductivity of Au@SiO2@Fe3O4/NG composites, the proposed electrochemical sensor exhibited a well-distributed nanostructure and high responsivity toward Pb(II). The sensor linearly responded to Pb2+ concentration in the range of 5―80 μg/L with a detection limit of 0.6 μg/L, indicating that this L-cysteine functionalized Au@SiO2@Fe3O4/NG composite could be a promising candidate material for the detection of Pb2+.

A Dual Read-out Molecularly Imprinted Composite Membrane Sensor Based on Zinc Porphyrin for the Detection of Dimethyl Methylphosphonate

Molecularly imprinted membrane-zinc porphyrin-mathacrylate(MIM-Zn-MAA), a dual read-out sensor based on a molecularly imprinted membrane, was developed to recognize and detect dimethyl methylphosphonate (DMMP) as an intermediate molecule of organophosphorus pesticides. The membranes were prepared via thermal polymerization of two functional monomers(zinc porphyrin and mathacrylate) on the surface of a glass slide functionalized with ethylene glycol dimethacrylate and azobisisobutyronitrile. The morphology of the as-synthesized MIM-Zn-MAA was determined with scanning electronic microscopy. The composite membranes exhibited macrovoid morphologies, which were affected by the functional monomers. These membranes were selectively adsorbed onto the template molecule and displayed higher adsorbing capacity toward DMMP compared with their structural analogs. Changes in the fluorescent spectra were qualitatively and quantitatively monitored via fluorescence photometry. Difference maps were also obtained using colorimetry before and after the reaction between MIM-Zn-MAA and DMMP at various concentrations. The maps showed a wide linear range varying from 0.1 µmol/L to 10 mmol/L with a low detection limit of 0.1 µmol/L. These preliminary results demonstrate that the as-fabricated dual read-out sensor displays good sensitivity and selectivity toward DMMP, indicaing its considerable potential in DMMP detection in real applications.

Ultra-sensitive fluorescence determination of chromium(VI) in aqueous solution based on selectively etching of protein-stabled gold nanoclusters

In this work, we have developed a simple, cost-effective and sensitive fluorescent method for the selective determination of chromium(VI) ions (Cr(VI)) in aqueous solution. In the presence of bromide ions (Br−), the strong oxidization of Cr(VI) enables it to selectively etch the bovine serum albumin-stabled gold nanoclusters (BSA-Au NCs) and formed AuBr2− complexes. Proportional fluorescence quenching of BSA-Au NCs induced by the leaching process was closely connected with concentrations of Cr(VI) and thus provided a new detecting strategy towards Cr(VI). Under optimal conditions, the amount-dependent fluorescent response was linearly correlated with the Cr(VI) concentrations ranging from 1.0 nM to 2.5 μM over 3 orders of magnitude, with a detection limit down to 0.6 nM. The as-developed strategy also performed satisfactory selectivity as well as excellent reproducibility. Moreover, this method had been successfully applied to monitor Cr(VI) with real river water samples which demonstrated the potential for field applications.