Fabrication And Research Of Electrochemical Biosensor Based On Three-dimensional CNS@ AuNPs And PAni/PdNPs Nanocomposites

The electrochemical biosensor is an instrument which is sensitive to biomass and converts its concentration into electrical signals.It is a system consisting of immobilized biosensitive materials as identification elements(including biologically active substances such as enzymes,antibodies,antigens,microorganisms,cells,tissues,nucleic acids),and appropriate signal converters.The electrochemical biosensor constructed by the new nano-materials which has the advantages of high sensitivity,simple operation,easy detection,good stability and low cost.It can be monitored on-line in the more complicated environment.It has a broad application in the electrocatalytic environment,clinical medicine and other fields.The nanoparticles have the characteristics of large specific surface area,high activity and specificity.We use the green method of synthesis of nano-materials as an electrochemical sensor sensor platform.The use of these materials can make the electrode surface possess good biocompatibility,provide a large surface area and rapid electron transport rate,and also increase the amount of biomolecules immobilization,thereby enhancing the response signal which makes the electrochemical biosensor analysis performance improve significantly.By combining nanoscience and technology,a highly sensitive biosensor is established for bioanalysis.The main research work is as follows:1.Lung cancer now is a major disease that threatens human health.Its early diagnosis is of great significance.In this work,we build an electrochemical cytosensor based on CNS @ AuNPs composite nano-materials to achieve the quantitative detection of lung adenoma cells(A549).The composite material was fixed on the surface of the electrode and anti-CEA was conjugated cross-linking to the surface of the modifide electrode.The carbon nanospheres were obtained by green synthesis method.Then the gold nanoparticles were joined to form a composite material with large specific surface area and fast electron transfer.anti-CEA was immobilized on the surface of the electrode,and the tumor cells were captured by the specific binding of the antibody to the carcinoembryonic antigen which overexpressed on the surface of the human lung adenocarcinoma cell.The tumor cells were quantitatively detected by differential pulse voltammetry(DPV).The detection of human lung adenocarcinoma cells ranging from 4.2 × 101 ~ 4.2 × 106 cells mL-1,and the detection limit was 14 cells mL-1.It has a low detection line.The construction of a new type of cell sensor have a better potential application in the early diagnosis of cancer,drug screening and cell adsorption research and other biomedical fields.2.Cholesterol is an important indicator of clinical biochemical testing.Too high or too low concentration of cholesterol in the human body are harmful to the health.In this study,the combination of polyaniline hydrogel with 3D structure and palladium nanoparticles was used as the sensing interface of biosensor.It has high conductivity and high specificity for cholesterol detection through covalent cross-linking of cholesterol oxidase.The polyaniline hydrogel with 3D structure has many advantages,such as simple and rapid synthesis method,low cost material,good biocompatibility and large specific surface area which can significantly increase the amount of biomolecules immobilization on the electrode surface.In this study,quantitative detection by cyclic voltammetry,the detection range of the cholesterol is 0.8-7mM: the detection line:0.27 mM.This experimental method provides a high detection sensitivity for the human body cholesterol analysis.