Chemical Sensors Based On Precious Metal Nanomaterials

Precious metal nanomaterials are new nanomaterials developed in recent years,which have unique physical and chemical properties and are widely used in various fields such as biology,medicine and environmental protection.Among them,silver nanomaterials are one of the hot spots.By preparing silver nanomaterials with different morphologies and adding various types of protective agents and modifiers,a variety of chemical sensors can be developed.This kind of sensor has good biocompatibility and high comprehensive detection performance,so it has very important research significance.In the first chapter,the characteristics of noble metal nanomaterials,the preparation methods of noble metal nanomaterials with different morphology,the application of nanomaterials in the detection of heavy metal ions and glucose and the overall research ideas of this paper are summarized.In the second chapter,an electrochemical sensor based on the amplification of silver nanoparticles was studied to detect Cr³⁺.Gold and silver nanoparticles were synthesized by chemical reduction method.ITO/Au NPs/MSA probes were prepared by calcination at high temperature using mercaptosuccinic acid（MSA）as surface modifier.Cr³⁺ with multiple coordination bonds could respectively form complexes with MSA-Au NPs and MSA-Ag NPs.Due to the electrical signal amplification of Ag NPs,Cr³⁺could be sensitively and indirectly detected by anodic stripping voltammetry.The sensor had a good linear relationship between 10^-8-10^-10 M and the detection limit was 5×10^-11 M.The recoveries were all up to standard in the range of 95.6%-100.1%.In the third chapter,a probe sensor based on the fluorescence enhancement of silver nanoclusters was developed to detect Fe³⁺.In general,fluorescence probe sensors used the fluorescence signal quenching phenomenon of Ag₁₅ to realize detection.In this chapter,weak fluorescence agent Ag₃₀@BSA was synthesized.Ag atoms were oxidized to Ag⁺ through the etching reaction between Fe³⁺ and the fluorescent probe,which reduced the number of Ag atoms in the clusters and resulted in the enhancement of fluorescence intensity.The concentration of Fe³⁺ was detected by the change of fluorescence intensity.The linear detection range of the fluorescent probe sensor was 2×10^-8-5×10^-5 M and the detection limit was 1×10^-8 M.The sensor had good selectivity and had been successfully applied to the determination of Fe³⁺ in many practical samples.In the fourth chapter,a glucose biosensor based on triangular Au-Ag nano-ring with GOD mimetic enzyme catalytic activity and chromogenic effect was studied.The Au-Ag triangular ring synthesized with triangular silver nanosheets as sacrificial template had glucose-like oxidase efect.When glucose was added under aerobic conditions,the Au-Ag triangular ring could catalyze the formation of disgluconic acid from glucose,resulting in the continuous dissolution of silver atoms.The absorbance of LSPR characteristic absorption peak decreased,which could be used to detect the glucose content.The method had good linearity in the range of 1× 10^-5-4 ×10^-4 M and the detection limit was 4 μm.It had good sensitivity and selectivity.