| Surface-enhanced Raman scattering?SERS?technology has become one of the most widely used spectroscopic methods for molecular specific and high-sensitivity detection in biophysics,biomedicine,and environmental science.In addition to its high sensitivity,SERS also has other advantages,such as its wide excitation wavelength range and high band resolution.SERS can perform on-site detection,which has unparalleled advantages and great potential in the future.Hence the development of a SERS analysis method for efficient in-situ detection of field samples has become more and more important.The traditional SERS substrates is a rigid material,which cannot meet the needs of actual measurement.However,the flexible SERS substrate can meet the practical requirements owing to its advantages such as good mechanical strength,portability,and easy cutting size.So far,many flexible substrates have been widely used,such as tape,graphene,and filter paper,but all of them have their own problems.Additionally,the SERS substrate with a three-dimensional network structure can increase the collection rate of surface samples.The large-scale preparation of SERS substrates with low cost and high enhancement factors are urgently required in the application of SERS practical detection.In this paper,three kinds of high-performance three-dimensional SERS substrates were prepared for the detection of pesticide residues by combining electrospun technology with SERS active metal nanoparticles.The main research contents are as follows:1?A hydrophobic poly?styrene-butadiene??SB?electrospun fiber membrane was prepared by electrospinning technology.The natural hydrophobicity of fiber membrane helps to fix the silver sol in a small area and prevents it random spreading,which can provide more"hot spots".The three-dimensional network structure surface of the SB membrane is conducive to the enrichment of samples and enhances the sensitivity of SERS detection.By optimizing the amount of silver sol,an Ag/SB substrate with the best SERS performance was prepared.After the substrate was folded 100 times,the detection of Rhodamine 6G?R6G?SERS signal before and after was not much different,indicating that the flexible SERS performance and mechanical properties were good.Compared with SERS substrates based on hydrophilic filter paper,Ag/SB substrate has better SERS performance.The Ag/SB substrate was successfully used to detect the pesticide triazophos in apple peels and apple juice.The sensitivity is as low as 2.5×10-88 mol/L,and the linear range is 5×10-5mol/L to 5×10-77 mol/L.2?CTAB was doped in the process of electrospinning,and Ag/CTAB-SB substrate was formed by adding silver nanoparticles to realize the SERS detection of pesticide residues imidacloprid.The binding fastness of SB to negatively charged silver nanoparticles was improved after CTAB is doped,and the stability of SERS performance of Ag/CTAB-SB substrate was greatly improved,three different batches of SERS substrates were selected for repeatability investigation,the relative standard deviation?RSD?value was 3.30%.With R6G as a Raman probe,Ag/CTAB-SB has a higher Raman enhancement factor.The Ag/CTAB-SB substrate can be used for high-sensitivity SERS detection of imidacloprid with a minimum detection limit of10-88 mol/L.In the spiked detection of fruit juice,the detection recovery rate is between 93.2%and 101.8%without sample pretreatment.3?Based on the stability of Au@Ag core-shell nanoparticles and strong surface plasmon resonance effect,it is beneficial to further improve the SERS performance of electrospun substrates.Using AgNPs as a template,Au@Ag core-shell nanoparticles were synthesized by alternative chemical reactions and loaded on SB electrospun fiber membranes to prepare heat-resistant SERS substrates.The structure and properties of the substrate were characterized by UV-visible spectroscopy,transmission electron microscopy?TEM?,scanning electron microscopy?SEM?and Raman spectroscopy.The Au@Ag/SB substrate was treated with two cycles of normal and temperature heating,and Rhodamine 6G was used as a probe.It was found that the surface of the substrate showed excellent thermal resistance and could be used for pesticide residue detection at higher temperatures.Taking thiram as an example,heating detection improves the sensitivity of SERS analysis and the detection limit can be as low as 5×10-88 mol/L. |
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