Controllable Synthesis Of Novel Silver-based Nanomaterials For Quantitative SERS Analysis

Surface-enhanced Raman scattering（SERS）has a huge application prospect in the field of ultra-sensitive analysis,and the key to realizing the application of SERS quantitative analysis is the controllable synthesis of substrate materials.Among many SERS substrates,silver（Ag）is the most active substrate material.However,how to precisely control its structural size and precise functional modification to meet the needs of quantitative analysis is a key issue that silver-based nanomaterials urgently need to solve.In this paper,a gentle nano-synthesis strategy is adopted.By loading Zn O nanoparticles on Ag nanosheets（Ag NS）,the dual advantages of（111）crystal plane orientation and charge transfer（CT）effect are realized,and the application of five benzodiazepines in serum is explored.The determination of the total amount of super drugs is aimed at precision medical problems;the use of electroless deposition to develop a uniform and stable Ag film on the orifice to achieve sensitive detection of a variety of analytes and explore the feasibility of SERS automated detection.The main contents are as follows:Part 1:Ag NS/Zn O nanocomposites used for SERS analysis of the total amount of benzodiazepines.In emergency medical situations,rapid total detection of benzodiazepines（BZDs）is essential to make accurate medical judgments.In this work,large-size（111）plane-oriented silver nanosheets modified with a small amount of zinc oxide nanoparticles are used as an excellent SERS substrate,which has the advantages of metal plane orientation and additional charge transfer effects from semiconductors.Through experiments and molecular dynamics simulations,the important bridging role of Zn O in the CT effect was systematically studied,which proved the importance of proper Zn O modification density.The optimized Ag NS/Zn O nanocomposite was used to establish a standard curve of estazolam,and the detection limit was as low as 0.5 n M.According to this curve,the total amount of five BZDs drugs（estazolam,oxazepam,alprazolam,triazolam,lorazepam）can be determined.This method has also been successfully applied in the metabolic process to monitor changes in the total concentration of BZDs in the serum of mice with the analysis time,and the results are consistent with the trend of liquid chromatography-mass spectrometry.Part 2:Homogeneous stable Ag film on the well plates and quantitative SERS detection of dye and biological small molecule.The 96-well plate technology is related to automatic sample preparation and simultaneous analysis based on low-cost well plates.In order to explore the potential application of 96-well plate technology in SERS detection,we prepared a uniform and stable Ag film on the well plate by electroless deposition method,which showed excellent performance in terms of sensitivity,uniformity,reproducibility and stability.,The enhancement factor is as high as 3.41×10~8.The Ag film was successfully used in the determination of organic dyes（rhodamine 6G and malachite green）in environmental water samples and small biological molecules（adenosine triphosphate and adenine）in urine matrix,showing satisfactory sensitivity and selection.Their limit of detection values were at nanomolar,even picomolar concentration.