Electrochemical immunoassay for serum parathyroid hormone using screen-printed carbon electrode and magnetic beads

Abstract

• A highly sensitive magneto immunosensor developed for parathyroid hormone detection. • The immunosensors only need small volume, minor wash steps, and low detection limit. • Magnetic beads-based immunosensors may be implementing for point-of-care testing. Using magnetic beads (MBs) in electrochemical immunosensors has been shown to improve their sensitivity, reduce analysis time, and minimize reaction volume. The antigen–antibody interaction can be improved with the correct orientation of the antibody using aminophenyl boronic acid (APBA) as the immobilized ligand. In this work, a highly sensitive magneto immunosensor to detect parathyroid hormone (PTH) was reported. The analysis was based on the immobilization of anti-PTH antibodies onto MBs followed by immunocapture, voltammetric and impedimetric assay. We introduce a facile two-step method to detect PTH by using MBs modified by APBA and antibody-peroxidase complex. Immunocapture of PTH by the antibodies takes place on the modified MBs, and the immunocomplexes are separated by a magnet on a screen-printed electrode. Electrochemical detection was performed by measuring the catalytic current and impedance. The APBA coating, antibody-peroxidase ratio, MB characterization, and electrochemical parameters were systematically investigated in this study. The PTH immunosensor exhibited a linear range between 10 and 300 pg mL −1 , with a limit of detection of 11.56 pg mL −1 by voltammetry and 49.30 pg mL −1 by impedance spectroscopy. A magneto immunosensor was successfully prepared by using modified MBs and a disposable electrode, which can be applied to analyze PTH quickly as a point of care device.