Construction Of Novel Type Of Silver Nanoparticles Based SERS Substrates And Its Analytical Detection Toward Toxic Metal Ions

With the continuous advancement of Surface Enhanced Raman Scattering?SERS?technology,various SERS substrates with different compositions,sizes and morphologies are emerging.The research content of the SERS effect mainly focuses on the enhancement mechanism,substrate construction and application of SERS technology.In this paper,based on the in-depth study of the aggregation response of silver nanoparticles,we are mainly committed to the preparation of novel SERS substrates by self-assembly technology,to realize the detection of heavy metal ions Cu2+and Ni2+.This thesis develops the following two parts:1.In terms of research on novel functional SERS substrates,we constructed a new type of integrated coordination SERS substrates 4-MBA-Ag NPs for selective and specific recognition detection of Cu²⁺.In particular:4-mercaptobenzoic acid?4-MBA?containing Raman labeled signal was modified on silver nanoparticles to prepare4-MBA-Ag NPs,which is a SERS substrates with both stability and ultra-sensitive detection performance.In order to test the stability of the synthesized SERS substrates,this paper characterizes the material by means of TEM,DLS,UV-vis,FT-IR,XRD,XPS,etc.,reflecting the stability of the novel functional SERS substrates.In the analysis and detection of Cu²⁺,by adding trace of Cu²⁺to the newly synthesized SERS substrates,the aggregation between 4-MBA-Ag NPs caused by Cu²⁺was characterized by TEM,DLS and UV-vis.The characterization results showed that chelation between the modified 4-MBA ligand and Cu²⁺can achieve different degrees of aggregation between 4-MBA-Ag NPs.Based on the‘hot spots'caused by the aggregation between the nanoparticles and the corresponding changes in the SERS spectral intensity,we constructed a 4-MBA-Ag NPs integrated SERS substrates for the SERS analysis and detection method of Cu²⁺and investigated its analytical performance.The experimental results show that it has a good analysis and detection performance for Cu²⁺.The results of Raman enhancement have a linear relationship with the ions concentration.The detection range was 1.0×10^-77 mol/L-7.0×10^-44 mol/L,and the lowest detection limit was 2.6×10^-77 mol/L,which showed higher sensitivity.In addition,this detection also behaves excellent selectivity.2.In the research of novel non-integrated bimolecular modified SERS substrates,we constructed a new non-integrated coordination SERS substrates GSH-Cys-Ag NPs for selective and specific recognition detection of Ni²⁺.In particular:Glutathione?GSH?and cysteine?Cys?,which do not contain Raman-labeled signals,were modified on silver nanoparticles to prepare a SERS substrate GSH-Cys-Ag NPs with both stability and ultra-sensitive detection performance.The materials were characterized by means of TEM,DLS,UV-vis,FT-IR,XRD,XPS,etc.,reflecting the stability of the novel non-integrated bimolecular modified SERS substrates.In the analysis and detection of Ni²⁺,by adding trace of Ni²⁺to the newly synthesized SERS substrate,the aggregation between GSH-Cys-Ag NPs caused by Ni²⁺was characterized by TEM,DLS,and UV-vis.The characterization results showed that the chelation between modified GSH,Cys ligand and Ni2+can achieve different degrees of aggregation between GSH-Cys-Ag NPs to generate Raman enhanced'hot spots',thereby enhancing the Raman spectrum signal.The Raman enhancement results showed a linear relationship with the ion concentration.The detection range was 1.0×10^-88 mol/L-5.0×10^-44 mol/L,and the lowest detection limit was 2.1×10^-55 mol/L.Such method also exhibits excellent sensitivity and selectivity.