In Situ Construction Of Novel Flexible SERS Substrates And Application In Environmental Analysis

Aiming at the global problem of increasingly serious environmental pollution,the development of low-cost and high-sensitive flexible surface-enhanced Raman scattering（SERS）substrates is of great significance for promoting rapid,sensitive and real-time detection application of SERS.However,how to realize the immobilization of SERS materials on flexible substrates through in-situ synthesis strategy to enhance the binding force of the substrate material is the focus and difficulty of current researches on flexible SERS substrates.In this thesis,using cellulose filter paper（CFP）and porous polydimethylsiloxane（PDMS）as flexible substrates,ZnO nanoflower/three-layer core-shell plasmonic metal（Ag@Au@Ag）and Ag nanoparticles were constructed by in-situ green synthesis methods.The substrates showed excellent tensile and ultrasonic damage resistance,and achieved the integration of enrichment and highly sensitive detection.It was successfully applied to detect three antibiotics in urine and crystal violet（CV）in Yellow River water samples with high sensitivity and selectivity.The low-cost,stable and flexible SERS substrates are expected to realize highly sensitive and on-site detection applications,which will play a huge application value in environmental security monitoring.Part I:In situ preparation of ZnO nanoflower/Ag@Au@Ag paper-based SERS substrate and enrichment and high-sensitivity detection of various antibiotics.The SERS sensor developed with flexible CFP is expected to be applied to the rapid detection of trace drugs in environmental samples.However,there are great challenges in how to achieve the integration of enrichment and high-sensitivity detection.In this work,flower-like ZnO nanorods were constructed on CFP by in situ growth.Then the three-layer core-shell structure plasma metal（Ag@Au@Ag）is further loaded by continuous chemical reduction.The substrate possesses multiple enhancement effects,including electromagnetic coupling of three-layer core-shell structure plasma-metal,charge transfer（CT）effect of ZnO-plasma metal and strong enrichment ability of CFP,facilitating high SERS activity and rapid detection of three antibiotics（amoxicillin,ciprofloxacin and tetracycline）.The limits of detection（LODs）of the three antibiotics were 1,10 and 10 n M,respectively,and the enrichment time required only 10 minutes.Through the built portable Raman spectrometer-mobile phone integrated system,the portable detection of ppb level antibiotics in urine was realized.PCA-LDA analysis was used to successfully distinguish the SERS spectral data of the three antibiotics and achieve accurate identification of the mixed samples.This active SERS substrate of low-cost,stable and flexible CFP is expected to be developed into chemical/biosensors for point-of-care detection of a variety of drugs in the field.Part II:Rapid SERS detection of environmental contaminants based on porous AgNPs@PDMS substrate.The microstructure and porous structure of nanomaterials are necessary to improve SERS activity and detection range.In this work,high-performance porous AgNPs@PDMS substrates were successfully prepared using a simple operating process.This substrate has a good pore size distribution,which significantly improves the noble metal loading and solves the problem of salt residue in the porous PDMS.The morphology and crystal structure of the crystals were characterized by SEM and X-ray diffraction.The AgNPs@PDMS substrate exhibited high SERS activity and selectivity and was successfully used for quantitative detection of CV with LOD values of 10^-10M.In addition,the substrate was successfully applied to the detection of CV in Yellow River water samples with satisfactory recoveries and RSD values.It has also been extended to the rapid and sensitive detection of other environmental pollutants.This high-efficiency porous SERS substrate shows excellent SERS detection ability,which will play an important role in dye and drug detection.