Label-free amperometic immunosensor for detection of brucella antibody

In order to improve the detection sensitivity of brucella antibody and discover diseased livestock earlier for reducing economic losses, a disposable label-free immunosensor for rapid and quantitative detection was prepared. It was made by modification of cysteamine onto screen-printed gold electrode surface and immobilization of antigens. By the method of cyclic voltammetry, it was shown that there is a linear relationship between the changes of peak current and the different brucella antibody concentrations within the range of 10-5~10-3 IU/mL, the relevant correlation coefficient is 0.9999 and the lower detection limit is 2.8×10-5 IU/mL. Furthermore, semi-differential transformation was applied to all of the cyclic voltammograms, the correlation between the changes of semi-differential values and the corresponding concentration of brucella antibody has been established, the correlation coefficient is 0.9929 and the lower detection limit is 2.7×10-6 IU/mL in the range of 10-5~10-3 IU/mL, and the correlation coefficient is 0.9992 in the range of 10-2~1 IU/mL. It was shown that the detection range and the lower detection limit were improved greatly by the semi-differential transformation.