Construction And Application Of Electrochemical Immunosensor Based On Functional Palladium Nanocomposites

Electrochemical immunosensor is a new type of biosensor constructed by combining immunoassay with electrochemical biosensing technology,which is used for detection of various antigens,haptens or antibodies.It is simple,rapid,sensitive and suitable for online connection,playing an important role in clinical diagnosis.The combination of nanotechnology and biosensors has good prospects for disease detection and treatment.Functionalized palladium nanoparticles have attracted extensive attention due to their special physicochemical properties.In this paper,a series of electrochemical immunosensors were constructed by combining carbon materials,metal oxides,metal nanoparticles and palladium nanoparticles.The specific research contents are as follows:1.Detection of hepatitis B surface antigen?HBsAg?by electrochemical immunosensor based on AuPdCu ternary alloy functionalized polymer nanospheres?PS?A label-free electrochemical immunosensor based on AuPdCu/N-GQDs@PS was constructed for the detection of HBsAg.AuPdCu/N-GQDs have excellent catalytic effect on hydrogen peroxide?H₂O₂?and good electrical conductivity.At the same time,PS have excellent biocompatibility and high specific surface area,which have the property of accelerating the electron transfer rate and can well immobilize the loaded antibody?Ab?.The immunosensor constructed by AuPdCu/N-GQDs@PS nanocomposite material realizes the amplification of electrochemical signals and improves the sensitivity of the immunosensor.The prepared immunosensor has high sensitivity and wide detection range.The linear range of detection of HBsAg is 10 fg mL^-150 ng mL^-1,and the detection limit is 3.3 fg mL^-1.2.A label-free electrochemical immunosensor based on TiO₂-NGO/Au@Pd HSs hetero-nanostructures was constructed for detection of human epididymis protein 4 antigen?HE4Ag?A label-free immunosensor was constructed with titanium dioxide functionalized nitrogen-doped graphene-loaded bimetallic Au@Pd holothurian-shaped nanoparticles?TiO₂-NGO/Au@Pd?as a signal amplification platform to achieve quantitative detection of HE4Ag.Nitrogen-doped graphene?NGO?has large specific surface area and good electrical conductivity.Titanium dioxide nanoparticles?TiO₂?have good biocompatibility and special catalytic properties.The hybridization of the NGO and can TiO₂ effectively increase the surface area electrodes and improve the catalytic performance of the signal amplification platform.In addition,bimetallic Au@Pd holothurian-shaped nanoparticles?Au@Pd HSs?can provide catalytic active sites in a large scale and can accelerate the electron transfer rate attribute to the synergy effect between Au and Pd,thereby effectively amplifying electrical signals to improve the sensitivity of immunosensors,and decreasing limit of detection.The constructed sensor has high sensitivity and wide detection range.The linear range of detection of HE4Ag is 40 fmol L^-160 nmol L^-1,and the detection limit is 13.33 fmol L^-1.3.Detection of human epididymis protein 4 antigen?HE4Ag?by electrochemical immunosensor based on enhanced electrocatalytic ability of Au@Pd urchin-shaped nanostructuresA sensitive sandwich-type electrochemical immunosensor was constructed using amine modified graphene supported gold nanorods?Au NRs/NH2-GS?as sensor platform and the improved electrocatalytic bimetallic Au@Pd urchin-shaped nanostructures?Au@Pd USs?as label to realize the quantitative determination of HE4Ag.Since the Au@Pd USs have a high crystal face index and can provide a large number of catalytic active sites,the synergy between Au and Pd can accelerate the electron transfer rate and effectively amplify the electrical signal.NH₂-GS has a large specific surface area and can carry more Au NRs.Meanwhile,Au NRs have good biocompatibility and conductivity,which can effectively increase the loading of HE4 antibody and accelerate the electron transfer efficiency on the electrode surface.The constructed sensor has high sensitivity and wide detection range.The linear range of detection of HE4Ag is 1 pmol L^-150 nmol L^-1,and the detection limit is 0.33 pmol L^-1.