AN IMMUNOLOGICAL INTERLEUKIN-6 CAPACITIVE BIOSENSOR USING PERTURBATION WITH A POTENTIOSTATIC STEP

An instrument for potentiostatic capacitance measurements, based on pe rturbation with a potentiostatic step was used. The capacitive sensor consisted of self-assembled sulfur compounds on gold to which antibodi es towards Interleukine 6, Il-16, had been immobilized. The biosensor was part of a potentiostatic three-electrode system with an extra refe rence electrode. Two different methods using epoxy- or carbodiimide co upling of the polyclonal antibodies were compared. The antigen Il-6 co uld be detected from 5 x 10(-16) to 5 x 10(-13) M with one immobilizat ion method and to more than 5 X 10(-9) M with the other. No labels wer e necessary since the binding of the antigen was detected directly. Th e insulating properties of the different layers of the biosensor were investigated. (C) 1998 Elsevier Science S.A. All rights reserved.