Abstract: A new type of non labeled immunosensor for the determination of breast cancer antigen(CA15 3) was made by combining sol gel with cross link techniques and utilizing glutaraldehyde(GA) to link CA15 3 antibody(Ab) on the functional sol gel film, so the sol gel/GA/Ab layer was immobilized on the surface of platinum disk electrode. Infrared spectrum(IR) and cyclic voltammetry(CV) were employed to investigate the structure and the electrochemical characteristics of the immunosensor, respectively. The linearity of CA15 3 in the range of 8—240 U/mL with a detection limit of 5 U/mL and the correlation coefficient of 0 998 are obtained. The experimental results show that the activity of the immobilized CA15 3 antibody is maintained better by this method, and the stability of the immunosensor is improved. The dependences of the potential response on pH, incubation time, sensitivity and reproducibility were studied, and the stability of the sensor was also evaluated. The immunosensor was found to be stable for about 30 days when stored in a dry state at 4 ℃. Satisfactory determination results of CA15 3 in serum samples were obtained by this method.

Key words: Sol gel, Cross link technique, Breast cancer, Immunosensor