Study On The Application Of Electrochemical And Electrochemiluminescent Immunosensor Based On Functioned Nanocomposite

With the characters of easy design,high sensitivity,good selectivity,fast detection,electrochemical immunosensors have become one of the major analytical techniques for detecting biomolecules.In recent years,nanotechnology has been gradually applied to the field of biosensors,and gotten a breakthrough.Therein,nanocomposite materials because of the properties of the controllable preparation,has attracted widespread attention in biological sensors field.（1）A novel label-free electrochemical immunosensor for the detection of alpha fetoprotein（AFP）has been developed by immobilizing anti-AFP on graphene sheet（GS）and thionine（TH）modified glassy carbon electrode.The modification procedure was characterized by cyclic voltammetry（CV）.The detection is based on the peak current change of the modified electrode before and after the antigen–antibody reaction.Tests relating to the detection of AFP demonstrated that the immunosensor exhibited high sensitivity,wide linear range(0.05-2.00 ng?mL^-1),low detection limit(5.77 pg?mL^-1 based S/N=3)and good long-term stability.The reliability of the developed immunosensor has been proved by the detection of AFP in serum samples with satisfactory results.（2）For the specificity of prostate cancer markers,protsate specific antigen（PSA）has been widely used in prostate cancer screening,diagnosis,and treatment after monitoring.In normal male serum,PSA can only be detected in traces of 0-4 ng?mL^-1.In this paper,we constructed an electrochemical immunosensor for PSA detection using a nanocomposite film of graphene sheets–methylene blue-chitosan（GS-MB-CS）as electrode material.The nanocomposite film showed high binding affinity to the electrode and was used to immobilize the antibody of PSA.The modification procedure was monitored by cyclic voltammetry（CV）.An amperometric biosensor was easily developed based on the response of peak current to the capture of PSA induced by specific antigen-antibody reactions.Under optimum conditions,the amperometric signal decreased linearly with PSA concentration(0.05-5.00 ng?mL^-1).A low limit of detection(13 pg?mL^-1)and a high selectivity are obtained.Moreover,the prepared immunosensor was applied for the analysis of PSA in serum samples with satisfactory results.The proposed method may have a promising future in biochemical assays for high selectivity,good reproducibility and stability.（3）In this paper,a new functionalization mesoporous silica nanoparticles（MSN）is compounded.It spreaded well and its grain diameter is about 100 nm.MSN compound was hybridization with ferriferrous oxide nanoparticles（Fe₃O₄）as a carrier to carry secondary antibodies tripolycyanamide and horseradish peroxidase（HRP）,composed of markers,the marker was prepared with the melamine electrochemical immunosensor with a good electrochemical activity.The electrode showed a high thermal stability.The immunosensor on the reduction of H₂O₂ showed good electrocatalytic response.The immunosensor in a low concentration of melamine with a linear detection,linear range is:0.05-10.0 ng·mL^-1,the detection limit is:0.03 ng·mL^-1,and has good stability and selectivity.（4）A novel ultrasensitive multiplexed immunoassay method was developed by platinum nanoparticles functionalized SBA-15（Pt@SBA-15）at a disposable immunosensor array.The immunosensor array was prepared by covalently immobilizing capture antibodies on graphene modified screen-printed carbon electrodes.After immunoreactions,the Pt@SBA-15 was captured on an immunosensor surface to catalyze the H₂O₂ which was seeming to the buffer solution.And the nonenzymatic and nonsubstrate nlectrochemical nmmunoassay was developed.Using diethylstilbestrol and estradiol as model analytes,this multiplexed immunoassay method showed wide linear ranges with the detection limits down to 0.6 and 3pg?mL^-1,respectively.The newly designed strategy avoided cross talk for the electrochemical immunoassay and,thus,provided a promising potential in clinical application.（5）An advanced electrogenerated chemiluminescence（ECL）immunosensor is reported for the sensitive detection of alpha fetoprotein（AFP）by using the grapheme-luminol system.The graphene film shows good electronic conductivity,fast response,and satisfactory stability,all of which holds great promise for the fabrication of ECL biosensors with improved sensitivity.Good electronic conductivity and fast response made graphene a good catalyst in the ECL of luminol.The ECL immunosensor has an extremely sensitive response to AFP in a linear range of 5 pg·mL^-1-14 ng·mL^-1 with a detection limit of 2.0 pg·mL^-1.The proposed sensor exhibits high specificity,good reproducibility,and long time stability,and may become a promising technique for protein detection.