The Investigation Of Metallic Supported Nanomaterials Applied In Electrochemical Biosensors

At present,tumor markers were applied to auxiliary diagnosis of many malignancies.Therefore,the sensitive detection of tumor markers plays an important role in early diagnosis of cancer.Electrochemical biosensors are utilized by more and more researchers in the detection of tumor markers due to its advantages such as simple preparation method,fast analysis,high sensitivity and low cost.In this paper,a series of metal-supported nanomaterials with excellent electrochemical activity were prepared by different methods,which were used to construct electrochemical biosensors for the quantitative detection of tumor markers.Metal nanomaterials with good biocompatibility are helpful to maintain the biological activity of biomolecules,and have excellent catalytic and conductive properties that can effectively promote the electron transfer of the electrochemical system,amplify the electrochemical signals.Metal nanomaterials are supported on carbon nanomaterials,metal oxides or other substances that with electrochemical activity,which effectively improves the analytical performance of the biosensor.This paper mainly studies from the following aspects:In this section,a sandwich-type electrochemical immunosensor for the sensitive detection of prostate specific antigen?PSA?was fabricated based on electrodeposited gold as the substrate material and Pd-Ag HDs@MWCNTs-NH₂ as the labels of secondary antibody?Ab₂?.Ag nanoparticles overgrows on Pd nano-octahedron by the method of sulfur ion-assisted,Pd-Ag heterodimers not only exhibited good catalytic activity towards hydrogen peroxide?H₂O₂?reduction but also can effectively maintain the biological activity of the antibody.MWCNTs-NH₂ with large specific surface area,superior conductivity and good hydrophilicity was used as the supporting materials of Pd-Ag HDs.This method can effectively reduce the agglomeration of nanoparticles.It plays a significant role in improving analytical performance of immunosensor.The proposed immunosensor with a detection range from 0.1 pg/mL to 30 ng/mL and a detection limit of 0.03 pg/mL can be successfully used in real sample analysis.In this section,a sandwich-type electrochemical immunosensor achieved the quantitative detection of alpha fetoprotein?AFP?using Au@MPTES-GS as substrate material to capture primary antibody?Ab₁?and Pt NPs/Co₃O₄/graphene as the labels of Ab₂.Due to the presence of Co₃O₄,graphene sheets agglomeration can be effectively prevented,and an electron transfer network is formed,which facilitates the electron transfer of the immunosensor.Co₃O₄ itself has a significant peroxidase activity,the catalytic activity and biocompatibility has been significantly enhanced after loading platinum nanoparticles.Under this signal amplification strategy,the detection range of AFP was 0.1 pg/mL to 60 ng/mL and the detection limit was 0.029pg/mL.The selectivity,reproducibility and practical value of the immunosensor were also evaluated.In this section,Fe₃O₄ nanospheres were synthesized by hydrothermal method.Fe₃O₄ nanospheres affinity was improved after amino functionalization,which is conducive to zirconium ferrocyanide adsorption on the surface of the nanospheres by electrostatic effect.Zirconium ferrocyanide is used as an electron mediator to provide electrochemical signals and has good ability to catalyze the reduction of H₂O₂.In order to enhance the electrochemical signal and increase the amount of the loading antibody,gold nanoparticles were loaded on the surface of the Zirconium ferrocyanide encapsulated Fe₃O₄ nanospheres.A label-free electrochemical immunosensor was fabricated using the nanocomposite as a signal amplification platform to quantify carcinoembryonic antigen?CEA?.The immunosensor showed a lower limit of detection of 0.15 pg/mL and a wide linear range of 0.5 pg/mL to 50ng/mL.In this section,an irregular bulk Cu₂O@Co₃O₄ nanomaterial was prepared by a simple chemical method and pompon-like Pd@Pt nanoparticles were prepared by morphology control.The nanocomposite exhibited excellent catalytic activity for toward the reduction of H₂O₂ due to their large specific surface area,good biocompatibility and synergism among the components after the two are bonded by chemical bonds.The multiple signal amplification of the immunosensor was realized and the ultrasensitive detection of PSA was completed using this nanocomposite as the labels of Ab₂.The detection linear range was 0.01 pg/mL to 100 ng/mL and the detection limit reached 2.0 fg/mL.Has good selectivity and stability testing,with potential practical value.And the immunosensor has a good selectivity,stability testing and potential practical value.