Research And Application Of Functionalized Gold And Silver Nanoparticles In Metal Ion Colorimetric Analysis

The particles of the size range of1?100nm were considered as nanoparticles. Inrecent years, nanoparticles became eye-catching because of their unique physical,chemical, biological properities. Especially, silver nanoparticles (AgNPs) and goldnanoparticles (AuNPs) focus on the research of the optical properties. The mostimportant features of AgNPs and AuNPs is with a strong surface plasmon resonance(SPR). Due to the size, shape, interparticle distances，and surrounding medium, thevisible wavelength range which would change. AgNPs and AuNPs showed differentcolors in the state of dispersion and aggregation. We could distinguish roughly onlyby the naked eye. Based on this, AgNPs and AuNPs had begun to be widely used inthe design into a selective colorimetric sensors for many target detection. Firstly, thispaper synthesized the silver and gold nanoparticies and did the characterization byultraviolet spectrophotometer, then studied the response between some smallmolecules atfer successful modiifcation to the particle surface and metal ions.Compared with traditional methods, this method had a lot of advantages such as goodselectivity, simple operation，low cost，low test line, short test time and so on.I. Selective detection of Cadmiumion in aqueous solution based onCalconcarboxylic acid-capped silver nanoparticlesColorimetric assay of heavy metalions using the modified AuNPs or AgNPs hadbeen proved to be a rapid，very sensitive and highly selective method. In this paper，we reported on a colorimetric probe for the determination of Cd(II). It was based onthe use of silver nanoparticles that had been capped with calconcarboxylic acid. Theabsorption spectrum and solution color of CCA-AgNPs underwent dramatic changeson exposure to Cd(II) with a new absorption peak appearing at522nm. It showedthat the aggregation of CCA-AgNPs was induced by Cd(II). Under optimumconditions, there was a linear relationship between the ratio of the absorbances at522nm and393nm，respectively, and the concentration of Cd(II) was in the0.227\iM to3.18|iM range.The method showed good selectivity for Cd(II) over other metal ions,and the lowest concentration was0,227jjM seen from the UV/Vis absorption spectra.The sensing system showed a certain application in the region for monitoring waterquality. II. Rapid colorimetric detection of Cr(III) method based on2-(2-Aminothiazole-4-yl)-2-methoxyiminoacetic acid functionalized silvernanoparticlesIn this study, a colorimetric detection method based on2-(2-Aminothiazole-4-yl)-2-methoxyiminoacetic acid (ATMAA) functionalizedsilver nanoparticles for Cr(IU) in aqueous solution is reported. The method pirnciplewas based on the aggregation of ATMAA-AgNPs induced by Cr(TII), which led tored-shift of the surface plasmon resonance (SPR) peak of ATMAA-AgNPs. UV-visabsorption spectra was used to demonstrate the aggregation of ATMAA-AgNPs.Some parameters affecting the detection including solution pH, reaction time and theconcentration of ATMAA were optimized. Under the optimized conditions, a goodlinear relationship was obtained between the ratio (A570/A393) of the absorbance at570nm to at393nm and the concentration of Cr(III). The method showed selectivedetection toward Cr(III) against other common metal ions and allowed detection ofconcentrations as low as0.0971gM to be achieved visually with in2min,Forthermore, the method was applied for detecting race Cr(IlI) in real water samples.EI. S3elective detection of Cr+in aqueous solution based on sodium chloride-mediated gold nanoparticlesA sensitive and selective colorimetric assay method for the detection of Cr(III) hasbeen developed using sodium chloride modulatory gold nanoparticles.The absorptionspectrum and solution color of NaCl-AgNPs underwent dramatic changes on exposureto Cr(III) with a new absorption peak appearing at700nm.Under optimum conditions,there was a linear relationship between the ratio of the absorbances at700nm and521nm，respectively, and the concentration of Cr(Ifl) was in the0.909jxM to9.09fiMrange. The method showed a good selectivity for Cr(III) over other metal ions. Thesensing system showed a certain application in the region for monitoring waterquality.