Construction Of SERS Magnetic Immunosensor And Application Of HCE1 Detection In Human Serum

Surface-enahanced Raman Spectroscopy（SERS）has many advantages such as high sensitivity,fast,high spectral resolution,and non-destructive.It can not only directly detect analytes,but also achieve indirect detection through derivation or sensing.,Has been widely used in many fields such as food and drug safety,environmental monitoring and analytical science.However,the current development of SERS still faces many problems that need to be solved urgently,such as sensitivity,reproducibility,and repeatability.Therefore,the application of SERS in various fields also needs to start with the development of practical,quantitative and reliable SERS detection technology,focusing on several aspects such as high sensitivity,high reproducibility,enhanced substrate preparation and construction of highly selective detection strategies.Based on this,this paper proposes a new strategy for the analysis and detection of highly selective SERS sensors in complex systems,and successfully uses it for the analysis and detection of carboxylesterase 1（h CE1）in liver cancer serum samples.The specific research work mainly from the following aspects Expand:1.Using ferroferric oxide（Fe₃O₄）magnetic particles as the core and silicon dioxide（SiO₂）as the coating shell,nano-silver particles are deposited on the surface by the seed method to prepare Fe₃O₄with high activity and core-shell structure SiO₂@Ag NPs surface enhanced Raman spectroscopy（SERS）active substrate.Its morphology and structure were characterized by scanning electron microscope（SEM）,transmission electron microscope（TEM）,energy spectroscopy（EDS）,X-ray diffraction（XRD）and Fourier transform infrared spectroscopy（FT-IR）.The substrate has uniform particle size and uniform dispersion.The SERS substrate was characterized by oxacillin as a model molecule.The results show that the composite substrate has extremely high sensitivity to oxacillin and the detection limit is 1×10^-11 mol/L.2.Hepatocellular carcinoma（HCC）is one of the common cancers,which seriously endangers human life and health.Human carboxylesterase 1（h CE1）is one of the important members of the serine hydrolase superfamily.It is closely related to the occurrence of hepatocellular carcinoma and can be used as a serum marker for early diagnosis of liver cancer.Based on the aforementioned work,we have developed a SERS-based magnetic immunosensor.By using a sandwich structure composed of a SERS tag,a magnetic support substrate and a target antigen（h CE1）,it can specifically identify and trace traces of h CE1 in human serum Detection.The SERS tag is4-mercaptobenzoic acid（4-MBA）labeled Ag NPs,and the support substrate is composed of Fe₃O₄@SiO₂@Ag NPs magnetic nanocomposite material functionalized on the h CE1antibody surface.The prepared magnetic immune SERS sensor exhibits excellent selectivity and extremely high sensitivity for h CE1 detection.The logarithm of SERS signal and h CE1 concentration（10 ng/m L～1.0 mg/m L）showed a wide linear range,and the detection limit of h CE1 reached 0.1 ng/m L.The results show that the sensor can be used for the rapid determination of trace h CE1 in human serum without complicated sample preparation.In addition,the immunosensor has good reproducibility and stability,and has broad development prospects in the quantitative detection of other tumor markers in early clinical diagnosis.3.Bimetallic Ag@Au nanoparticles have received extensive attention due to their unique optical properties and SERS molecular sensing capabilities.In this paper,through the growth process mediated by seeds,bimetallic Ag@Au nanoparticles with uniform morphology,uniform particle size and good dispersion are synthesized.Compared with Ag NPs,the prepared Ag@Au nanoparticles show stronger chemical stability,and the SERS performance of Ag@Au nanoparticles has been greatly improved with an enhancement factor of 3.9×10⁵.In addition,Ag@Au nanoparticles have high sensitivity,can detect amoxicillin at a concentration of 10^-11 M,and have good spectral reproducibility.4.In order to further improve the sensitivity,stability and reproducibility of the SERS magnetic immunosensor.In this chapter,we use molybdenum disulfide（MoS₂）nanoparticles modified bimetallic gold and silver nanoparticles（Ag@Au NP_S）as SERS probes（Ag@Au-MoS₂NP_S）to improve the stability of SERS probes.At the same time,a PDMS chip integrating multiple collection devices was prepared,and the SERS magnetic immunosensor forming the sandwich structure was collected and detected in a specific area on the PDMS chip collection device to improve its detection sensitivity and repeatability.Because MoS₂ is a graphene-like material,it has a large specific surface area and stability.Compared with Ag@Au NPs and Ag@Au NPs-graphene oxide（GO）,the chemical stability of the prepared Ag@Au-MoS₂NP_SSERS probe.Biocompatibility has been significantly improved,expanding its application in biosensors.In this chapter,4-MBA is used as the SERS signal molecule,Ag@Au-MoS₂ is used as the SERS probe,h CE1 antibody surface functionalized Fe₃O₄@SiO₂@Ag NPs magnetic nanomaterial is used as the SERS active substrate,and the sandwich structure is formed after combining the h CE1 to be tested SERS detection of h CE1 in the serum of multiple liver cancer patients on the PDMS chip at the same time.The detection limit was 1 pg/m L,and the RSD was 7.8%after repeated tests.Compared with the enzyme-linked immunosorbent assay（ELISA）,the results were not significantly different.This method is helpful for the application of SERS in the fields of food safety and medicine.