Preparation And Application Of Metallic Composite Nanostructure Based Sers Substrate

The discovery of Surface Enhanced Raman Scattering(SERS)technology has attracted numerous researchers to study a lot in biomedical and POCT applications.The preparation of chemically stable,reproducible,low toxic biosensing substrates or chemical detection substrates is the key to the practical application of SERS technology.In the actual application process,monodisperse bare metallic nanoparticles cannot meet the actual needs due to the single function.The preparation of metallic compositing nanoparticles can achieve different SERS analysis targets.This project is aimed at the application of biosensing and POCT applications,and the studies of the preparation process and application of composite surface-enhanced Raman substrates.The performance of SERS biosensing strongly relies on the surface properties of SERS substrates which are generally noble metallic nanoparticles.Surfactants have been always used for the preparation of nanoparticles to maintain the stability of nano-colloids,that greatly affect the efficiency of SERS sensing due to the space blocking between SERS substrates and analytes,as well as the interference of intrinsic Raman signals from surfactant themselves.Herein,without adding any surfactant,we synthesized a nano-sized graphene oxide(NGO)coated metallic nanoparticles,which were used as efficient SERS substrates,taking the advantages of surfactant free surface with inert protective effect of the GO shell.The Ag@NGO nanoparticles demonstrated excellent SERS sensing capability and can be used as biocompatible nanoprobes for intracellular biosensing.The ?-? interaction between the anti-cancer drug of doxorubicin(DOX,a typical anti-cancer drug)and GO facilitates DOX loaded onto Ag@NGO nanoparticles as drug delivery nano-carriers as well.Therefore,Ag@NGO holds great potential as a theragnostic platform with capabilities of both SERS biosensing and drug delivery.With the advanced development of the miniaturized Raman spectroscopy,surface enhanced Raman spectroscopy(SERS)has extended its applications into the field of Point of Care Testing(POCT)and demonstrated its great significance in economy and society.In the SERS-based analysis and/or sensing system,the preparation of low cost,high-performance SERS substrate is critically important.In this project,simple process technology is utilized to fabricate the silver nanoparticles(AgNPs)embedded nylon filter membrane(ANFM)as flexible paper-based SERS chips.By characterizing the typical analytes with the miniaturized smartphone-based Raman analyzer,the proposed SERS chips fabricated by method of vacuum filtration have successfully demonstrated good sensitivity,repeatability and stability.The limit of detection(LOD)can approach 1 pmol for Rhodamine 6G(RH6G)and 10 pmol for both crystal violet(CV)and malachite green(MG),respectively.With the help of microporous structure of the membrane,the ANFM based SERS chips can implement the separat ion of small molecules from complex mixture and can achieve “purified” SERS signals of targeted molecules.Besides,with the function of anti-friction resistance and flexibility,the ANFM can serve as SERS papers to pre-concentrate the contaminates by multiple swapping and further enhance the SERS signals for point of care analysis.Therefore,we demonstrate multi-functions of the flexible ANFM based SERS chips,which provides a promising solution for the POCT analysis with SERS technique on account of its flexibility and low fabrication cost.