| Different shapes of silver nanoparticals on silicon,glass and TiO2 films for SERS substrate were prepared by using liquid phase reduction method and hydrothermal process method.The properties of uniformity and sensitivity of the substrates were investigated.Using the prepared SERS substrates for the detection of caffeine and antibiotics,the linear correlation between the concentration of caffeine and the concentration of antibioti cs with the characteristic peaks of SERS were found accoding to the data fitting.The main research contents and conclusions are as follows:1?The nano-silver SERS substrate based on different substrates was prepared by liquid phase reduction method.Silver nanoparticals sol was prepared by liquid phase reduction method with AgNO3 as the precursor,ascorbic acid as reductant,polyvinylpyrrolidone?PVP?as surfactant.Deposited silver nanoparticals sol on silicon wafer,glass and TiO2 films to get the three kinds of silver nanoparticals SERS substrate.The experimental results show that the nano-silver SERS substrate based on TiO2 films has the best Raman enhancement effect.The results showed that the minimum detection limit of R6G was 10-8 mol·L-1 by using the substrate.2?Using hydrothermal method to prepare nano-silver substrate.Using polyol method combined with hydrothermal,the introduction of different concentrations of Na2S can be different purity of nano-silver.By adjusting the concentration of Na2S and dropping time,you can control the yield of nano-silver wire.The nano-silver sol was deposited on the silicon wafer to obtain nano-silver SERS substrate.The results showed that when 0.1mL of PVP was dissolved in 10 mL of 0.3 mM Na2S ethylene glycol solution,the silver nitrate glycol solution was added dropwise to the PVP solution?containing Na2S?over 2 min,then the solution showed a faint dark red.The mixed solution was then transferred to a hydrothermal reactor and placed in a drying oven at a preset temperature of 160°C for 2.5 hours.The prepared silver nanoparticles were linear in shape and the nanowires were about 500 nm in diameter.The Raman enhancement of the silver nanoparticles SERS substrate was the best.The results showed that th e average diameter of the substrate was 500 nm,and the minimum detection limit of R6G was 10-8mol·L-1.3?Detection of caffeine based on the prepared SERS substrate.Raman test of caffeine using the prepared SERS substrate which was obtained in the research.With the study on the qualitative analysis of Raman spectra and the analysis of caffeine concentration,the results show that the characteristic peaks of SERS spectra of caffeine mainly occurred in the 550cm-1?637 cm-1?736 cm-1?796 cm-1?925 cm-1?1016 cm-1?1235 cm-1?1281cm-1?1323 cm-1?1594 cm-1?1694 cm-1 peak intensity around the most obvious.With the increase of the concentration of caffeine,characteristic peak intensity increases gradually,showed a linear correlation,the linear correlation coefficient reached to 0.98.Through the comparison and analysis,we can estimate the concentrations of caffeine through the characteristic Raman intensity when the concentration of caffeine in 10-7 mol·L-110-10 mol·L-1.4?The antibiotic was detected based on the prepared SERS substrate.The Raman spectra of the antibiotics were analyzed qualitatively by Raman test.The Raman spectra were analyzed by the linear correlation between the concentration of antibiotics and the peak intensity of SERS spectra.The results show that the characteristic peaks of ceftazidime are mainly located at the following positions:695 cm-1?C=S stretching vibration?,1025cm-1?C=C stretching vibration?,1578 cm-1?C=N stretching vibration?,1644cm-1?the olefin C=C stretching vibration?.With the increase of the concentration of ceftazidime,characteristic peak intensity increases gradually,showed a linear correlation,the linear correlation coefficient reached to 0.98.Through the comparison and analysis,we can estimate the con centrations of ceftazidime through the characteristic Raman intensity at 745 cm-1 when the concentration of pesticide dimethoate in 0.01 ppm100 ppm.The results show that the characteristic peaks of ceftriaxone sodium are mainly located at the following positions:343 cm-1?C-C-N deformation?,688 cm-1?C-S stretching vibration?,758 cm-1?lactam ring respiratory vibration?,1372 cm-1?C=O stretching in the Carboxylic acid and-OH deformation coupling vibration?,1489 cm-1?C=C stretching vibration?,1573 cm-1?C=N stretching vibration?,1634 cm-1?Amide C=O stretching vibration?.According to the comparison,the correlation coefficient between the concentration of ceftriaxone sodium and the Raman shift peak intensity at 935 cm-1 was the highest.Through analysis,we can estimate the concentrations of ceftazidime through the characteristic Raman intensity at 935 cm-1 when the concentration of pesticide dimethoate in 0.1 ppm100 ppm. |
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