Application Of Highly Sensitive Nano-Gold/Silver Gap Coupling SERS Substrate In Extraction And Analysis Of Enviromnental Toxic Substances

With the development of society and the increase of human activities,environmental pollutants produced in production activities such as industry and agriculture are increasing.Many environmental toxic substances can cause toxic effects such as carcinogenesis in the human body.They can accumulate in the body by the food chain,threaten human health.They can also migrate in environmental media,causing water pollution,soil pollution,and air pollution.They pose a threat to environmental problems.Therefore,environmental toxic substances are an important research object of environmental monitoring.Surface enhanced Raman spectroscopy(SERS)is a molecular vibrational spectroscopy.It is a detection technique based on surface sensitivity.Surface-enhanced Raman spectroscopy has the advantages of being fast,easy to operate,free from water environment interference,requiring only a small amount of samples,and enabling nondestructive testing.Substance identification and structural analysis can be carried out through the fingerprint characteristics such as Raman peak position,peak number,and peak height provided by SERS.It is can also be used to study the interaction of target molecules on the substrate such as adsorption behavior and mechanism of action.In recent years,the rapid development of portable Raman instruments has provided a hardware foundation for SERS field analysis.SERS is widely used in environmental monitoring,material analysis,food safety,biomedicine,security and anti-terrorism fields.In this paper,we obtained sensitive SERS substrate with excellent SERS enhancement,good stability and biocompatibility by controlling the morphology of bimetallic nanoparticles and the gap coupling.This article discusses the following aspects.Pentachlorophenol and pentachloronitrobenzene are toxic,degradable and cumulative.Long-term exposure can cause damage to the liver,kidneys and nervous system of human.Silver nanowires with porous nano-coating were obtained by electrochemistry,and then functioned with cysteamine.By regulating the charge distribution of the silver wire,a nano-silver gap-coupling SERS substrate with electrostatically inducing extraction capability was obtained.Pentachlorophenol and pentachloronitrobenzene were rapid SERS identified successfully in-situ.The experimental parameters were optimized,and the stability,uniformity and reusability of the substrate were evaluated.The adsorption mechanism of the substrate was discussed by the electric double layer model.This work proposes SERS methods that can quickly identify pentachlorophenol and pentachloronitrobenzene in surface water in situ,which can provide potential applications for rapid on-site analysis of ionic environmental pollutants and handling of environmental emergencies.2.Malachite green,crystal violet and thiuram,which are often used illegally in aquaculture and transportation,can effectively kill microorganisms such as bacteria,fungi and algae.The fungicides will remain in the aquatic products for a long time.After entering the human body by the food chain,they will cause carcinogenic and teratogenic effects.The nano-silver obtained by electrochemical roughening was used to the extraction of the bactericide,and then the nano-silver wire assembled with the bactericide was immersed in the gold sol which prepared by the sodium citrate method.The gold nanoparticles were assembled on the surface of silver wire though electrostatic interaction.Dual-material sensitive SERS substrates were obtained using the gold-silver gap coupling and the stability of gold nanoparticles.The nanostructure and overall morphology of the substrate were characterized by TEM,SEM and UV,while the performance of the substrate was investigated.The effects of size effect and other factors of SERS enhancement were discussed.The SERS responses to malachite green,crystal violet and thiuram on the substrates were investigated.The experimental conditions were optimized.The sensitive SERS method of malachite green,crystal violet and thiuram were developed,and aquatic product samples were detected.The FDTD was used to theoretically simulate the electromagnetic field distribution of AuNPs with AgNPs on the surface of nano-silver.The theoretical calculation results were in agreement with the experimental results.3.Fenthion is a highly effective organophosphate insecticide and is widely used in the cultivation.The toxicity of fenthion is related to its inhibition of acetylcholinesterase.Fenthion can be self-assembled on the nano silver wires obtained by electrochemical roughening.Gold nanoparticles were generated by the reaction of ascorbic acid with HAuCl4,and then they were assembled in situ on the nano silver forming a gold-silver gap coupling sensitive SERS substrate.The substrate was characterized by SEM,AFM and thermal imaging.FDTD calculations about the substrate were performed.The interaction sites and interaction forces between fenthion and protein were discussed using the SERS change of fenthion before and after incubation of protein molecules,combining with molecular simulation docking method.This work provides an experimental basis for studying the toxicity of fenthion,revealing the mechanism of organic phosphorus and protein molecules.