Study On Immunosensors Based On Oxide Nanoparticles And Multi-walled Carbon Nanotube

Electrochemical immunosensor are widely used for clinical diagnosis,environmental inspection and food analysis,and have been have gained considerable attention due to their small volume,intrinsic selectivity,fast analytical time,simple measurement,high sensitivity and low cost, It has been reported that the performance of biosensors largely contact with the fabrication of biorecognition molecule.Thus,it's important work how to immobilize effectively on the cleaned electrode with biorecognition molecule in high amounts with retention of their bioactivity.In this article,we have constructed several immunoelectrodes immobilized antibody onto substrate electrode based on SiO₂ and methylene blue(MB) nanocomposite,nano-MnO₂ and chitosan(CS) composite,gold nanoparticles(nano-Au) and multi-walled carbon nanotube(MWNT) as matrixes. The detailed materials are shown as follows:1.Amperometrie immunosensor for carcinoembryonic antigen based on ehitosan entrapped SiO₂ and methylene blue nanoeompositeAn amperometric immunosensor for the detection of carcinoembryonic antigen(CEA) has been developed by means of sol-gel techniques.SiO₂+MB-CS nanocomposite membrane was combined.Subsequently,nano-Au was adsorbed by CS with a large amount of amido matrixes, which owned a high surface area,good bioconsistent.Carcinoembryonic antibody(anti-CEA) was adsorbed by nano-Au firmly.Then a potentiometric immunosensor with good sensitivity and stability was prepared.The characteristics of the modified electrode at different stages of modification were studied by cyclic voltammetry(CV) and transmission electron microscope (TEM).The resulting immunosensor exhibits wide linear range from 1.0 to 80.0 ng·mL^-1 with a detection limit of 0.333 ng·mL^-1.The correlation coefficient is 0.9978.2.Study on immunosensor based on gold nanoparticles/chitosan and MnO₂ nanoparticles composite membrane/prussian blue modified gold electrode A novel amperometric immunosensor for the detection of carcinoembryonic antigen(CEA) has been developed by means of electrodeposition and electrostatic adsorption techniques.In this study,Prussian blue(PB) was used as a mediator to amplify the current signal.And nano-MnO₂/CS composite with positively charged was adsorbed on the negatively charged PB.Subsequently, nano-Au was immobilized by CS.A large amount of carcinoembryonic antibody(anti-CEA) was adsorbed by nano-Au.Then an amPerometric immunosensor with good sensitivity and stability was made.The characteristics of the modified electrode at different stages of modification were studied by using cyclic voltammetry(CV)and scanning electron microscope(SEM).The performances of the immunosensor were studied in detail.The immunosensor showed a specific response to CEA in the range 0.25 to 8.0 ng·mL^-1 and 8.0 to 100 ng·mL^-1 with a detection limit of 0.083 ng·mL^-1.The correlation coefficient is 0.9982.The immunosensor was used to analyze the serum samples with satisfactory results.3.An immunosensor based on poly(sodium 4-styresulfonate) grated-carbon nanotube/niekel hexacyanoferrate/gold nanoparticles modified gold electrode.A novel immunosensor has been developed by electropolymerizing Nickel Hexacyanoferrate (NiHCF) on to a Poly(sodium 4-styrenesulfonate)(PSS)-grafted Multi-walled Carbon Nanotube (MWNT) and electro-depositing nano-Au for determination of prostate specific antigen(PSA). After the developed immunosensor was incubated with different concentrations of PSA samples at 25℃for 35 min,the current response decreased with an increasing PSA concentration in the sample solution.The decreased percentage of the current was proportional to PSA concentration ranging froml.5 to 35 ng·mL^-1 PSA with a detection limit of 0.51 ng·mL^-1 PSA(S/N = 3). Analytical results of 50 specimens using the developed immunosensor showed satisfactory agreement with those using ELISA,indicating the method to be a promising alternative for detecting PSA in clinical diagnosis.