Design of an electrochemical sensor based on 3-thiophene methanol and 3-methylthiophene supported molecularly imprinted polymer for the sensitive and selective detection of levothyroxine

Abstract

Levothyroxine (L-T4) is the most frequently prescribed drug to treat thyroid hormone deficiency. Herein, a levothyroxine-specific sensor was designed using the molecular imprinting method to increase the selectivity of the target molecule on the electrode surface and prevent interference effects. 3-thiophene methanol (3-TMeOH) and 3-methyl thiophene (3-MT) monomers were electro-polymerized as molecularly imprinted polymer (MIP) on the surface of a glassy carbon electrode (GCE) in the presence of L-T4. Gaps were created on the surface of the designed electrode to fit the target molecule by removing L-T4 molecules. This way, L-T4-specific selective structures were formed on the sensors' surface. The results showed that under optimized conditions, the fabricated modified sensor (3-TMeOH/3-MT@MIP/GCE) exhibited a linear response in the concentration range of 1.0–5.7 μM with limit of determination, limit of quantitation, and sensitivity values  of 1.83 nM, 5.50 nM, and 0.0023 A.L.mmol⁻¹.cm⁻², respectively. The analytical method validation process of the voltammetric determination method using the sensor selective to L-T4 was completed following the method's intended use. The designed modified sensor exhibited high sensitivity, repeatability, excellent stability, selectivity, and high precision and accuracy.