ALTERNATING-CURRENT FIELD ENHANCED LATEX IMMUNOASSAY FOR HUMAN MYOGLOBIN AS MEASURED BY IMAGE-ANALYSIS

Square-wave alternating current (ac) was used to accelerate the immunoreaction of latex beads with human myoglobin. The antibody to human myoglobin was adsorbed on the surface of latex beads which had been labeled with a fluorescent dye. The antibody bound latex beads were reacted with its antigen, and the agglutinated beads were counted using a fluorescence image analysis system consisting of a fluorescent microscope. charge-coupled device (CCD) camera, monitor and personal computer. The lowest detection limit for myoglobin was 1 ng/ml with this method. The immunoreaction was accomplished by applying an ac field for 1 min at different potentials and frequencies. This conjugation effect from a square-wave ac is probably due to pearl-chain formation which increases the collision frequency between latex beads.