Self-assembly Of The Antibody Film Igg Immune Sensor

A highly sensitive immunosensor by means of covalent coupling of anti-immunologloblin G (anti-IgG ) onto a gold or a silver electrode which is modified by SAMs has been prepared and its potentiometric response to the immunoglobulin G (IgG) was investigated. The preparation of the immunosensor is described as follows:1. The formation of SAMs on the surface of the electrode.2, The anti-IgG was covalently linked with the SAMs with the aid of NHS and EDC.The prepared IgG immunosensor was found to have a sensitively Nernst response to IgG because of the antigen-antibody reaction. The change of potential from beginning to end (the potentiometric difference, A E) is made of quantifying parameter.Different substrates such as gold planar, gold wire and silver wire is used to fabricate this immunosensor. It shows that the immunosensor using gold wire is more sensitive and more stable.As for the immunosensor made of gold wire, the following research has been conducted.1 .Two kinds of thio-alkohols ( SH(CH2)10COOH and EG60CH2COOH ) were used to immobilize the anti-lgG onto the surface of gold electrode made of gold wire. The characteristics of the immunosensors prepared by these two thio-alkohols have been investigated in detail, respectively.For the immunosensor using EG60CH2COOH, the response time to IgG is less than 8 min and the calibration curve for MlgG was obtained in the concentration range of 0.04-0.5ng. mL-1 with the correlation coefficient of 0.9986.The detection limit was estimated to be less than 0.04 ng. mL-1.For the immunosensor using SH(CH2)10COOH, the response time to IgG is less than 7 min and the calibration curve for MlgG was obtained in the concentration range of 0.1-0.4 ng.ml-1 with the correlation coefficient of 0.9982. The detection limit was estimated to be less than 0.1 ng.mL-1.2.The responses of these two immunosensors to MlgG at different tempratures and acids have also been monitored respectively. It shows that the sui liable temprature and acid for immunosensors using EG60CH2COOH is 40 , PH-7.4 and 35 , PH=5. 5 for the immunosensor using SH(CH2)10COOH.3.A comparation between these two immunosensors has also been done. It shows that the immunosensor using EG60CH2COOH has a larger detection range and a better linear relationship between the potentiometric difference ( K) and the concentration of IgG. The reason has also been dicussed.4.The characterization of the SH(CH2)10COOH SAM on gold surface has been made by electroanalytical method. The characterization of the antibody layer has also been done.As for the immunosensor made of silver wire, the following research has been conducted.1. The responses of this immunosensor to MIgG at different tempratures and acids have been determined. It shows that the suiltable temprature and acid for this immunosensor is 40 ,PH=5. 5.2. The lifetime of the immunosensor has also been studied. It shows that it can be reused no more than 3 days when it is stored in PH=7.4 buffer at room temperature. This research is still on study.