A novel sensitive biosensor for Ca2+ based on electropolymerized melatonin modified electrode

An electropolymerized melatonin modified glassy carbon electrode (EPMT/GCE) was prepared by electrochemically polymerizing of melatonin in a 0.04 mol l−1 perchloric acid solution. In KCl solution, Ca2+ was found to perform a reversible complex reaction on the EPMT/GCE to produce a sharp complex adsorption wave. The configuration of the electropolymerized membrane was characterized by scanning electron microscope and various electrochemical techniques. Based on which, a novel sensitive Ca2+ electrochemical sensor was established. The peak current showed a linear relationship with Ca2+ concentration in range of 6.2 × 10−7–1.0 × 10−4 mol l−1 with detection limit of 4.5 × 10−7 mol l−1. The developed electrochemical sensor has been used for determination of Ca2+ in body fluid.