[Colorimetric assay of perfluorooctanesulfonate based on gold nanoparticles].

For the property of persistent, bioaccumulation and genetic toxicity, perfluorooctanesulfonate (PFOS) is classified as a sort of persistent organic pollutants (POPs). It is significant to develop a novel assay for the determination of PFOS. In this work, we create a new colorimetric assay for PFOS in which the positively-charged gold nanoparticles (AuNPs) work as a nano-probe. This method works on the aggregation of AuNPs induced by PFOS via electrostatic interaction. The stable monodisperse AuNPs coated by cysteamine present color of red wine and the addition of PFOS can make the monodispersed AuNPs aggregated resulting in the color change from wine red to reddish purple with a red-shift in ultraviolet-visible absorption spectrum. The experimental results show that AuNPs has a characteristic absorption peak (524 nm), as well as a wide absorption peak (650 nm) and the absorption signal intensity is proportional to the PFOS content in a range of 0. 8-8. 0 µmo .l L-1. According to these, we developed a method based on ultraviolet-visible absorption and colorimetric to detect PFOS with the detection limit of 80 nmol . L-1. The scanning electron microscope (SEM) was investigated and the photos show that the stable AuNPs are made and the degree of AuNPs aggregation is related with PFOS concentration. The effect tests of coexisting substances in system show that common anions had less impact on the system and inorganic metal ions had some interference, which can be get rid of by cat- ion exchange resin in real sample. This assay was applied to detect PFOS in tap water with a recovery range of 87. 5%-118% and RSD 4. 4%. It is a novel application of AuNPs-based probe for PFOS detection. The proposed method has more advantages such as rapidity, low-cost and simplicity than conventional ones. In addition, it has the visual sensing function and the difference of color can be sensed by naked eyes directly, which produce ideas of real-time colorimetric strategies of nanoprobe application in environmental pollutant detection.

[Gold nanoparticles-based localized surface plasmon resonance scattering analysis method for the determination of trace amounts of Hg(II)].

Heavy-metal ions pose severe risks for human health and the environment. In particular, mercury-based pollutants are of great environmental concern because of the high toxicity of many Hg compounds. It is important to monitor the levels of potentially toxic metal Hg(II) in aquatic ecosystems. Gold nanoparticles (AuNPs) as nanomaterials have been generally studied. It is because their unique electrical, chemical, optical, and catalytic properties, AuNPs have caused widespread interest for applications in biological and chemical analysis and detection. In the present work, the authors took advantage of the aggregation-induced localized surface plasmon resonance (LSPR) light scattering signal change of sodium thioglycolate functionalized AuNPs in aqueous solutions to develop a highly efficient optical sensor for Hg(II). The as-modified AuNPs demonstrate that high negative charge densities exist on their surfaces at pH 9.0 Britton-Robinson (BR) buffer solution. The AuNPs occur aggregate in solution through chelation in the presence of Hg(II). The scanning electron microscope (SEM) images for the AuNPs display typical shapes of these AuNPs as regular and almost individual spherical particles. The color change of the AuNPs solution was induced by the addition of Hg(II) and it immediately changed from red to purple due to the aggregation. Under optimum conditions, a good linear relationship was obtained from 0.08 to 0.8 µmol x L(-1) with a correlation coefficient of 0.997 6, and the limit of detection (LOD) was 8.0 nmol x L(-1). PEG20000 was employed as a system stabilizer. The proposed method has an excellent selectivity for Hg(II) in aqueous medium over other metal ions. The optimum test of reaction conditions, including the amount of AuNPs, pH value, reaction stability and ionic strength, were also investigated. This method has been used for determination of Hg(II) successfully in environmental water sample. This approach manifested several advantages including short analysis time, high sensitivity, low cost, excellent selectivity and ease of operation.