POLYANILINE LABEL-BASED CONDUCTOMETRIC SENSOR FOR IGG DETECTION

A new method based on a biochemical binding system is developed for de tecting the presence and measuring the concentration of a definite ana lyte in fluids. The conductometric scheme of detection has been employ ed for detection of the binding reaction of immunoglobulins. Two ident ical pairs of gold interdigitated electrodes deposited on the insulati ng solid support have been used as a detector. An electrically conduct ing polymer, namely polyaniline, has been proposed as a label for immu nosensor development. A set of water-soluble forms of polyaniline with different molecular weights and oxidation levels have been prepared b y chemical oxidation of aniline and characterized using gel-permeation chromatography. The acceptability of different kinds of polyaniline, and the selectivity and sensitivity of sensor response have been studi ed. The method of antibody detection in competitive electroimmunoassay has been developed. The lowest antigen concentration which may be det ected in the competitive mode was found to be about 500 ng/ml. The res ults of impedance spectroscopy measurements obtained for different sta tes of the electrodes are analyzed in order to clarify the mechanism o f the sensor response.