Electroanalytical Sensor Based on Molecularly Imprinted Polymer-Modified Screen- Printed Carbon Electrode for the Determination of Thyroxine

A susceptible voltammetric sensor for thyroxine is designed and generated by electro polymerization of molecularly imprinted polymer (MIP). Thyroxine selective molecularly imprinted polymer is synthesized by electropolymerization of the p-phenylenediamine‒ resorcinol mixture directly on the screen-printed carbon electrode (SPCE) surface in the presence of the thyroxine molecules. Electropolymerization of monomers deposited a film on the electrode surface which blocked ferricyanide reduction. Elimination of the Thyroxine forms the cavities which caused a remarkably improved ferricyanide signal which was again blocked after the rebinding of thyroxine. The decrease of the ferricyanide peak of the MIP electrode depended linearly on the thyroxine concentration. Various factors affecting the current response of the electrode were studied and optimized. This sensor shows a linear response range of 1 × 10^-8 - 2 × 10^-6M and a lower detection limit of 5 × 10^-9 M. The sensor was successfully applied to the detection of thyroxine in human plasma samples.