Preparation And Application Of Liposome Based SERS Substrate With Core-shell Structure

Surface Enhanced Raman Spectroscopy（SERS）,as a practical vibration Spectroscopy technology,has shown unique advantages in chemical,environmental protection,food analysis and biomedical fields due to its rapid,nondestructive detection and high sensitivity in low concentration detection.In the research of SERS technology,the design and synthesis of SERS substrate materials has always been a direction concerned.For the traditional substrate materials,no breakthrough progress has been made in the research of maintaining the stability of SERS signals and the detection of specific molecules.Based on the series of problems,a new type of liposome-based core-shell structure substrate material is designed and constructed for the technology of SERS in this paper.The work content of this paper is mainly divided into the following two parts:First,gold nanoparticles（AuNPs）were prepared by seed growth method for SERS detection.Then,based on the ionic liquid,the imidazole ring grafted on N atom with long hydrocarbon chain was used to synthesis the ionic liquid-based liposome（IL-liposome）.Subsequently,using the self-assembly properties of liposome monomers in aqueous solution and the different charging properties between AuNPs and IL-liposome monomers,a liposome-based SERS substrate AuNP@liposome with a core-shell structure was prepared,and explored the stability of its core-shell structure in a complex environment and its surface ion exchange.The results show that in the core-shell structure of the particles,the presence of AuNPs prevents the emulsification of surfactants on the surface liposome membrane and helps the liposome bilayer membrane to remain stable in a complex solvent environment.Since the liposome head group on the surface of the prepared SERS substrate material is positively charged,AuNP@liposome has good reactivity with the negatively charged inorganic PF₆^-.After that,it further studied around the SERS detection performance of AuNP@liposome.Unlike conventional SERS substrate materials that carry probe molecules with sulfhydryl groups,the head of the liposome on the AuNP@liposome substrate is positively charged,so it can load anion probes by electrostatic interaction.Similarly,it can selectively charge probe molecules with different charges.The results show that the prepared AuNP@liposome can only be selectively combined with negatively charged anion probes,and it is also universally applicable to other anion probes.In a complex system containing multiple probe solutions,even if the concentration of cation probes is ten times higher than that of anion probes,the substrate shows excellent charge selectivity.In addition,as a base material of core-shell structure,the liposome bilayers on the surface of AuNP@liposome isolates the direct contact between the probe molecules and AuNPs and prevents the fluorescence quenching of probe molecules.There were also strong fluorescence background signals in the SERS spectra at the same time.This phenomenon means that AuNP@liposome can be further used for the detection of SHINERS（Shell-isolated nanoparticle-enhanced Raman spectroscopy）.The SERS substrate uses liposome membrane as the outer shell layer,which is different from the conventional Shiners substrate covered by inorganic materials.It constructs a soft core-shell particle model,simplifies the preparation method of SHINERS substrate,and enhances the application range of core-shell materials in the SERS field.And due to the excellent biocompatibility of liposomes,this material also can be used in the field of life sciences with a great application potential.