Electrochemical sensors based on L-tryptophan molecularly imprinted polypyrrole and polyaniline

The aim of this work was to compare two different conducting polymers (polypyrrole and polyaniline) in the design of the molecularly imprinted polymer (MIP). An L-tryptophan was selected as a template molecule in such MIP-based layers deposited on the graphite electrodes. Further, the MIPs with L-tryptophan imprints were applied in the design of electrochemical sensors for the detection of L-tryptophan. All polymer layers were electrochemically deposited on the electrode surface by the application of potential cycling. The characteristics of all modified electrodes were evaluated by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The results demonstrate that the molecularly imprinted polypyrrole MIPpy layer has a greater affinity toward L-tryptophan molecules in comparison with other layers evaluated in this study. This observation proves that polypyrrole is more suitable for the design of the molecularly imprinted polymer-based sensors for the determination of L-tryptophan than polyaniline. The linear relationship between the current intensity of DPV signal obtained on the molecularly imprinted polypyrrole and the concentration of L-tryptophan was obtained from 50 mu M to 100 mu M with the limit of detection (LOD) of 16.6 mu M and the limit of quantitation (LOQ) of 49.8 mu M.