Preparation Of Functional Composite SERS Substrates And Their Detection Of Environmental Pollutants

Surface Enhanced Raman Scattering?SERS?is a new spectral analysis technique with advantages of high sensitivity and fast nondestructive testing,which has great application prospect in determination of trace samples.SERS can obtain the spectral "fingerprint" peak of the detected matter and provide molecular level information with structural features.As the performance is directly determined by the SERS substrate,the design and preparation of SERS substrate is very important.Now,multi-functional composites assembled by a couple of materials has aroused widespread concern.In this paper,several multi-functional composites based on the silver nano-particles are proposed to achieve fast,sensitive and reliable SERS detection of target molecules.The main contents of this article are as follows:First,silver nanoparticles were modified by amphiphilic polymer poly?propylene glycol?bis?2-aminopropyl ether??PEA?to synthesize Ag @ PEA composite nanostructure.Hydrophobic PPO?polypropylene oxide?chain of PEA could promote the adsorption of analyte molecules on the surface of the substrate through hydrophobic interaction.And a series of characterization and optimization of the composite nanoparticles were carried out.The detection limits for dicofol and pyrene were 5 ppm and 5 x 10-7M,respectively.This SERS platform combines Ag @ PEA composite nanoparticles with portable Raman instrument,which is simple,rapid,sensitive and reliable,and has wide application prospect in food safety monitoring.Second,a method of preparing new Fe₃O₄ @ PDA @ Ag composite nanoparticles was proposed.Briefly,PDA was self-polymerized on the surface of Fe₃O₄ nanoparticles to synthsis Fe₃O₄ @ PDA,then Ag nanoparticles were deposited on the PDA by in-situ reduction to obtain Fe₃O₄ @ PDA @ Ag composite nanoparticles.These composite nanoparticles can achieve adsorption,separation,enrichment and detection of the organic pollutants,with the advantages of magnetic response of Fe₃O₄ and good adsorption of PDA.The organic dyes?methylene blue?and pesticide residues?thiram?was detected as low as 10-10 M and 10-8 M,respectively.This Fe₃O₄ @ PDA @ Ag NPs-based SERS method is extremely simple,sensitive,quick and cost-effective,which can be applied for on-site SERS detection.