Application Of Surface Enhanced Raman Bioanalysis Based On Laser Mediated Enrichment

Surface enhanced Raman scattering（SERS）has been widely used in the field of biomedicine as a kind of ultra-sensitive and unlabeled molecular detection method.However,the SERS detection in liquid phase was dependent on the high combination between analytes and SERS hot spots.Therefore,it was a great challenge to realize the SERS detection of SERS analytes in highly diluted solutions.In addition,for SERS detection process of target analytes in practical biological samples,non-target analytes often competitively adsorbed on the SERS substrate surface.As a consequence,the signal of analytes was likely to be covered by impurities or coexisting molecules.Moreover,non-target analytes also result in strong background fluorescence sometimes.These reasons make it difficult to detect tra ce amounts of biological samples,so pre concentration and separation of target analyte is necessary before SERS detection.However,the pretreatment of biochemical samples usually requires several steps and takes several hours even more than ten hours,th erefore,the simple and quick enrichment detection method is of great significance to the SERS detection of biological samples.In addition,the uniformity of the SERS substrate,the distribution of target molecules and other various factors from measureme nt conditions and micro-environment also affect the reliability of SERS quantitative analysis.Therefore,finding a way to improve the reliability of SERS quantitative detection has an important research value.To solve the above problems,this work constr ucts an efficient laser-mediated enrichment strategy for the detection of drug molecules in serum and rat blood based on the fact that the graphene-isolated Au nanocrystal（GIAN）,which has excellent SERS performance and great photothermal efficiency,can self-assemble on the interface between H₂O and Dichloromethane（DCM）and enrich the tested molecule throughπ-πinteraction at the same time.The specific content is as follows:（1）In the second chapter,GIAN particles were prepared and characterized.The stability,SERS enhanced effect,interface self-assembly characteristics and photothermal conversion efficiency of the particles in different organic solvents were investigated.According to the characteristics of GIAN that can self-assemble at the H₂O-DCM interface and have great photothermal conversion effect,a laser-mediated enrichment strategy was constructed,specifically as follows.GIAN with excellent photothermal heating capability at the H₂O-DCM interface under the irradiation of laser would produce a large amount of heat to make the internal DCM oil droplets move up and down reciprocately accompanying with the volatilization of DCM,and finally achieves the concentration of the target analyte in this process.The results show that this strategy is simple and efficient,and the enrichment effect is remarkable.This strategy provides a time-saving and easy-to-operate pretreatment method for chromatographic,mass spectrometry,Raman and other detection methods..（2）In the third chapter,9,10-Bis（phenylacetyl）anthracene（BPEA）was used as the model molecule to explore the application of this laser-mediated enrichment system in SERS detection.The distribution coefficient of BPEA in DCM is greater than that in H₂O and the graphitic shell of GIAN can be used to realize the trace detection of BPEA molecules throughπ-πinteraction with BPEA.The experiment proved that the strategy has the advantages of high sensitivity,high quantitative analysis accuracy,great reproducibility,high uniformity,and the detection of trace analytes in complex environments.（3）The fourth chapter mainly introduces the application of laser-mediated enrichment system in SERS detection of carbamazepine（CBZ）.The effect SRES quantitative analysis of CBZ and SERS trace detecti on of CBZ in water phase,fetal calf serum,and real rat blood samples demonstrated this strategy possesses great potential in pharmacokinetic monitoring.