AN IMMUNOSENSOR BASED ON DISPOSABLE ELECTRODES FOR RAPID ESTIMATION OF FATTY-ACID-BINDING PROTEIN, AN EARLY MARKER OF MYOCARDIAL-INFARCTION

An immunosensor was developed that allows the rapid estimation of fatt y acid-binding protein (FABP) in neat plasma samples. FABP is released into the blood following myocardial infarction and elevated levels ar e found already 3h after onset of symptoms. The sensor is based on scr een-printed graphite working and Ag/AgCl reference electrodes and an i mmunosandwich procedure for the quantification of FABP. The capture an tibodies are bound to the electrode surface by adsorption and will tra p FABP from the plasma sample. The sandwich is then completed by a sec ond monoclonal antibody conjugated with alkaline phosphatase. The enzy me converts p-aminophenylphosphate to p-aminophenol, which is detected amperometrically at + 350mV. The high binding capacity and very short response time of the working electrode allow within 20 min the quanti fication of FABP in the measuring range 10-350 ng/ml, covering the pat hological range of FABP release into the circulation. Measurements of plasma samples from a patient with acute myocardial infarction show an excellent correlation of the results obtained with the biosensor and those obtained with the respective reference ELISA. Owing to the long stability of the electrodes with immobilized capture antibody ( > 3 mo nths) a quick application without the need of labour-intensive electro de preparation is possible. (C) 1997 Published by Elsevier Science Lim ited.