Application Of Electrochemical Immunoassay Based On Ferrocene-functionalized Nanomaterials

Cancer markers serve as marks for the physiological state of a cell within a certain period of time and changes in the disease process as well as pathogenic process. The accurately and quickly to detecting the level of the cancer marker is very important in the clinical diagnosis and treatment of cancer. Therefore, the development of a highly sensitive and simple detection method is very imminent. Electrochemical immunosensors, combined with electrochemical analysis methods and immunological techniques, is an electrochemical biosensor possesses some advantage such as good sensitive, high selectivity, simple operation. There are three key problems in fabricating such kinds of electrochemical immunosensors. The first problem is how simple, fast and effective to immobilize a large number of antibodies on the electrode surface without denaturation. The second issue is how to accelerate the electron transfer between the redox active center of the mediator and the electrode surface. Finally, the question is how to develop immunosensor signal amplification technology.A series of novel electrochemical immunosensor were prepared based on ferrocene and nanomaterials and using signal amplification system.1. An electrochemical immunosensor was proposed based on Fc-COOH attached to the branched structure of multi-walled carbon nanotubes-chitosan（MWCNT-CS） on electrodes surface for the detection of Carcinoembryonic antigen（CEA）. MWCNT-CS coating contains active secondary reaction functional entities that could form covalent bonds with molecules containing carboxyl or aldehyde groups. A large number of Fc-COOH was attached to the branched structure. The electrode was further modified with PDA and AuNPs. The immunosensor showed a low limit of detection(0.002 ng·mL^-1) and a large linear range(0.01 ng·mL^-180 ng·mL^-1).2. A novel electrochemical immunesensor was developed for CEA based on carbon nanotubes-gold nanoparticles（CNTs-AuNPs） as platform and porous copper oxide nanowires@Ferrocene（pCuOw@Fc） as labels. The pCuOw were prepared by a simple decomposition of Cu（OH）₂ precursor. The immunesensor showed enhanced electrochemical performance toward the detection of CEA with a range from 0.005 ng·mL^-1 to 80 ng·mL^-1 and a detection limit of 0.0008 ng·mL^-1（S/N=3）.3. An electrochemical immunosensor was developed for the detection of CEA using Fe₃O₄@SiO₂-NH₂ as carriers and GO-AuNPs as platform. The Fe₃O₄@SiO₂-NH₂ surfaces were used as linked reagents for co-immobilization of Fc-COOH and Ab₂ to prepare the signal probe, and could hasten the decomposition of H₂O₂. The designed immunosensor show an excellent analytical performance wide dynamic response range of CEA concentration from 0.001 ng·mL^-1 to 80 ng·mL^-1 with a relatively low detection limit of 0.0002 ng·mL^-1（S/N=3）.4. A novel multiplexed electrochemical immunosensor was developed for the detection of alpha fetoprotein（AFP） and CEA using cuprous oxide-graphene oxide-β-cyclodextrin（Cu₂O-GO-CD） and GO-CD-Fc-COOH as probe, and GO-AuNPs as platform. The GO-CD displayed the excellent water-soluble and long-stability in water and exhibited rich capture capability to Fc-COOH and biomolecules. The linear ranges were from 0.001 ng·mL^-1 to 80 ng·mL^-1 for AFP and CEA, and the detection limits were 0.0002 ng·mL^-1 for AFP and 0.0001 ng·mL^-1 for CEA.