Abstract:

Using L-tryptophan(L-Trp) as template molecule and o-phenylenedia mine as functional monomer, the sensitive molecularly imprinted polymer films was prepared on the surface of gold electrode by in-situ polymerization. The performance of the imprinted electrode was characterized by cyclic voltammetry(CV), differential pulse voltammetry(DPV) and electro-chemical impedance spectroscopy(EIS). A linear relationship between oxidation peak current and concentration of L-Trp was obtained over a range from 1×10^-8 to 2×10^-7 mol/L with a detection limit of 0.3×10^-8 mol/L. From the selectivity experiments, the imprinting factor of L-Trp imprinted film was 3.72 and the selectivity factors of L-Trp compared to interferents were all larger than 1. Although a minor interference was generated by L-Tyr for its structure similar to L-Trp, the selectivity factor also reached 2.30. The results indicated that the imprinted polymer films had a good selectivity for L-Trp. The kinetics of recognition revealed a two-step process of the imprinted polymer films adsorbing L-Trp, which contains a fast binding process and a slow adsorption process.

Key words: L-tryptophan, Molecular imprinting, Electrochemical polymerization, Sensitive film, Recognition process