Ag-Polymer Based Hybrid Sers Substrates And Their Sensitivity To Methyl Parathion

Surface-enhanced Raman spectroscopy(SERS)has been shown various potential applications in the flied of environmental pollutant and dangerous chemicals monitoring,food inspection,biological analysis and disease diagnosis,owing to its high sensitivity and fingerprint specificity.For practical applications of SERS technology,it's necessary to develop simple and low-cost methods for large-area fabrication of desired SERS substrates with excellent SERS performance.The dissertation will be mainly focused on the electrospray,coaxial-electrospinning(co-electrospinning)and self-assembly of nanoparticles and their applications in the construction of plasmonic nanoparticles/polymer-based hybrid SERS substrates with high SERS activity,good signal reproducibility and high affinity for target molecules.Besdies,the influence of miscibility of core and shell solutions on the co-electrospinning process was also systematic studied.The main resluts of this dissertation can be summarized as follows:1.we reported the large-area fabrication of Ag-nanocubes(Ag-NCs)embedded in cellulose acetate(CA)microsphere membranes(denoted as Ag-NCs@CA-MS membranes)by the electrospray method.The huge surface area and excellent hydrophilicity of Ag-NCs@CA-MS membranes can promote the extraction of analyte molecules from the aqueous solution into the membranes.The Ag-NCs@CA-MS membranes showed relatively high SERS sensitivity and excellent signal reproducibility.Therefore the Ag-NCs@CA-MS membranes were applied for quantitative SERS-based analysis of methyl parathion(an organophosphorus pesticide)with a relatively high accuracy(detection error less than 30%).2.We present a simple and cost-effective approach for the electrospinning of CA nanofiber membranes embedded with aggregated Ag-NCs(denoted as aggregated-Ag-NCs@CA-NF membranes)by co-electrospinning of Ag-NCs dispersed CA/acetone-dimethylacetamide(DMAc)solution.Importantly,the acetone solvent could induce the aggregation of Ag-NCs.Owing to the strong plasmon coupling between the neighboring Ag-NCs in the aggregates,the aggregated-Ag-NCs@CA-NF membranes exhibited higher SERS activity than the Ag-NCs@CA-MS membranes.As a result,0.1 nM p-aminothiophenol and 10 nM methyl parathion could be identified,respectively.Therefore the aggregated-Ag-NCs@CA-NF membranes show promising potentials for SERS-based rapid detection of trace-level organic pollutants in environmental aqueous samples.3.We'performed a systematic research on the phenomenon and mechanism of the transformation of co-electrospun productions from nanofibers to microspheres during the co-electrospinning process with the CA/DMAc and CA/DMAc-acetone(2/1 v/v)solutions as core and shell fluids,respectively.The mixing of core and shell solutions was demonstrated to be responsible for the transformation.Besides,the uniform CA microspheres were fabricated by electrospraying of ?-cyclodextrin added CA/DMAc solution.4.We fabricated the polymer films with highly ordered micro-nano arrays by casting polymer solutions onto well-designed Si molds with micro-nano arrays,followed by curing and demolding.The process and technology of polymer solution casting,curing and demolding were investigated systematically.Subsequently,the plasmonic nanoparticles were assembled on the as-prepared polymer array films by capillary assembly.Besides,the influence of surfactants on the capillary assembly was also studied.