Development electrochemical sensor based on molecularly imprinted polymer for determination of levodopa

Levodopa (3,4-dihydroxyphenylalanine) also called L-dopa, is the precursor required by the brain to produce dopamine, a neurotransmitter. Levodopa crosses the protective blood–brain barrier, whereas dopamine itself cannot. Thus, levodopa is used to increase dopamine concentrations in the treatment of Parkinson’s disease (PD), dopamine-responsive and dystonia. However, an excessive amount of levodopa not only helpful but also make serious side effects such as gastritis, paranoia schizophrenia and epilepsy. With dangerous side effects of levodopa with long-term use on human health, this drug should be given an accurate analysis in both pharmaceutical formulations and biological fluids [1]. Forasmuch as levodopa contain phenolic hydroxyl and amino group respectively, which is electrochemically active and can be oxidized. Thus, electrochemical methods because of their good simplicity, sensitivity, and relatively fast response, low cost and good stability are the better choice for determination of levodopa. However, the signal to noise of bare electrode is insufficient to determine the trace level of levodopa. To overcome it, molecular imprinted polymer (MIP) is considered one of the best strategy owing to its pre-determined selectivity for an imprinted template. Molecular imprinting is a technique which is used to molecular recognition via self-assembly of functional monomers around a template molecule through the interaction between their functional groups. This technology has been developed for use in sensors since it can provide enhanced selectivity and/or sensitivity. In addition, molecularly imprinted polymers (MIP) benefit from ease of preparation along with good 14th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 12- 13 Dec, 2018 43 stability in chemical, physical and mechanical properties [2]. A considerable amount of research has been done on MIP based approach for levodopa determination. Levodopa showed a sensitive anodic peak in buffer solution of phosphate (pH=7.0) at the surface of MIP/GCE. The investigation and optimization of the effective factors on the response and electrochemical behavior of target levodopa on the surface of the modified electrode were accurately done. Levodopa response linearly within the range of 0.1-600.0 μM with detection limit of 0.05 μM. The function of this electrode in the determination of biological samples was satisfactory.