Preparation Of Surface Enhanced Raman Spectroscopy Substrate And Application In Organic Dyes

Surface enhanced Raman spectroscopy(SERS)has been widely used in many fields due to its advantages such as high sensitivity,rapid detection,strong specificity,and non-destructive samples.The SERS signal is closely related to the SERS active substrate.Different shapes,compositions,and sizes of substrates have effects on the sensitivity.The exploration of SERS substrates with remarkable preparation effects and good repeatability has gradually become a research hotspot in this field to meet the growing needs of various analysis and testing.Therefore,the main research contents of this paper are as follows:(1)Following the principles of green chemistry,using a simple,fast and harmless method to synthesize silver nanoparticles(AgNPs),using sodium alginate as a reducing agent and stabilizer,water as the reaction medium synthesizing by hydrothermal method.It is used in surface-enhanced Raman spectroscopy detection of organic dyes.Ultraviolet-visible spectrophotometer and transmission electron microscope were used to characterize and analyze AgNPs.Furthermore,the detection of low concentration dyes(methylene blue,rhodamine B,basic fuchsin)solution showed that the detection limit of the prepared AgNPs for these three dyes reached 10^-6 M the enhancement factor was between 10² and 10³.There are excellent enhancement effects.(2)The surface hydrophilicity and hydrophobicity of polydimethylsiloxane(PDMS)is changed by plasma device treatment.Based on the coffee ring effect,PDMS substrates with different hydrophilic and hydrophobic surfaces are prepared,methylene blue and Congo red dyes are selected as probe molecules.Add different coffee ring patterns on the prepared PDMS substrate,perform SERS detection,explore the intensity of the Raman signal,and select the most suitable solution;combine AgNPs with organic dye solutions of different concentrations(methylene blue,rhodamine B,rhodamine)6G,primary magenta,methyl orange and Congo red)were mixed and then dropped onto the PDMS substrate to form a coffee ring pattern for SERS detection.Finally,six organic dyes are mixed for SERS detection.The results show that the SERS substrate's signal intensity based on the coffee ring effect is higher than that of the solution SERS substrate.The enhancement factor can reach 3.8×104.The substrate stability is good the SERS signal can be identified for all six dye molecules.(3)Different chemical processes are used to reduce silver nitrate to prepare AgNPs with different morphologies:spherical AgNPs with varying diameters of the particle,silver nano-cubes,silver nano-hexagonal plates,silver triangular nano-plates,and flower-shaped nano-silver.Using MB dye as the probe molecule,we explored the enhancement effect of different morphologies of AgNPs on the Raman signal of MB aqueous solution and then prepared coffee rings on the PDMS substrate to further explore the enhancement effect.The results show that the coffee ring SERS substrate prepared with 79 nm AgNPs has the best enhancement effect than other morphologies of AgNPs,with a detection limit as low as 10^-8 M and an enhancement factor as high as 4.4×10⁶.Figure[39]table[12]reference[111]...