An Impedimetric Sensor for Levothyroxine Detection towards Point of Care Applications

Nanotechnology gains more interest in the field of medical applications due to the use of metallic and carbon-based nanomaterials to improve the detection of various biomolecules (e.g., hormones). Thus, we used bimetallic nanoparticles such as nickel-cobalt loaded on reduced graphene oxide for the sensitive detection of levothyroxine (LT4). LT4 is a medication used to adjust hormone concentration in the blood to a physiological level for various medical conditions, e.g., hypothyroidism. The goal of this article is to optimize an electrochemical sensor for quantification of LT4. To achieve optimum performances, we tested carbon film sensors modified with different nanostructured materials with electrocatalytic role towards LT4 sensitive detection and compared their parameters. We used electrochemical methods for the characterization of the nanostructured materials. We studied the oxidation mechanisms of LT4 together with the interfacial changes, which occur due to their electrochemical properties at sensor surfaces, by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). EIS was also the analytical method used for LT4 detection, where highest sensitivities and lowest detection limits in the picomolar range (6.1pM) were obtained. Thus, a very sensitive impedimetric sensor for LT4 detection was developed.