Abstract
An enzyme immunoelectrode system for monitoring theophylline has been developed. The immunoelectrode was composed of an oxygen electrode and an antibody-coupled membrane. Anti-theophylline antibody was covalently immobilized on a nylon net with dimethyl sulfate, 1, 6-hexanediamine, and glutaraldehyde. The reported method for obtaining antibody-coupled membrane was modified and the binding capacity of the membrane was characterized by using [8-3H] theophylline as a tracer. The assay procedure involved the competitive immunochemical reaction of the membrane-bound antibody with catalase-labelled and nonlabelled theophylline. The amount of labelled theophylline bound specifically on the membrane was determined electrochemically from the reducing current of the oxygen generated enzymatically. Under optimum conditions, theophylline could be determined in the concentration range from 9.0 to 90 ng/ml (5×10-8 to 5×10-7M). This immunoelectrode is highly specific for theophylline, and may be applicable as a drug sensor for clinical use.
