Electroanalytical sensor design based on molecular imprinted polymer for levothyroxine detection

Aim: The main aim of this study is to construct a molecularly imprinted polymer-based electroanalytical sensor which was chosen as a medication molecule, and Levothyroxine, a molecule used to treat hypothyroidism and Hashimoto's thyroiditis. The electrochemical concept of the sensor is based on the measurement of current owing to oxidation/reduction reactions occurring on the electrode surface and the application of a voltage in the electrochemical cell as a result. Material and Method: In order to maximize the selectivity of the target molecule on the electrode surface and reduce interference, a Levothyroxine-specific sensor design is combined with a molecular imprinting approach in this study. 3-thiophenemethanol and 3-methylthiophene monomers were electropolymerized on the surface of the glassy carbon electrode (GCE) in the presence of Levothyroxine. By eliminating the template molecules, gaps are produced on the surface of the intended electrode to fit the target molecule. As a result, the surface of the sensors develops Levothyroxine-selective structures. In addition, the second sensor design for the determination of Levothyroxine was carried out by dropping the polymer obtained as a result of the chemical polymerization of multi-walled carbon nanotube, tetrahydrofuran, triethoxy vinyl silane, and methacrylic acid onto the GCE surface. Results: The MIP-based modified sensor has a detection limit of 1.65 nM and a sensitivity of 0.023 for a linear range of 0.0010-0.0057 mM. The sensitivity of the chemical polymer-based modified sensor was calculated as 0.408 and the detection limit as 2.7 nM for the linear range of 0.002-0.044 mM. Conclusion: Analytical validation processes have been completed to prove the precision and accuracy of the designed new sensors and voltammetric determination method. Under optimum conditions, the modified sensors exhibited high sensitivity, repeatability, excellent stability, and selectivity along with high sensitivity and accuracy.