Molecularly Imprinted Electrochemical Sensor Based on 3D Wormlike PEDOT-PPy Polymer for the Sensitive Determination of Rutin in Flos Sophorae Immaturus

A molecularly imprinted polymer (MIP) with 3D worm-like nanorod structures was constructed by cyclic voltammetry (CV) polymerization, using 3,4-ethylenedioxythiophene (EDOT) and pyrrole (Py) as bifunctional monomers, and rutin as the template on a glassy carbon electrode (GCE). The optimum polymerization conditions of MIP were obtained by the orthogonal test. The range analysis suggested that the potential range was the most influential factor. Compared with MIP/1.5 and MIP/1.9, the MIP films prepared in the potential range of 0–1.7 V (MIP/1.7) had better current response to rutin, faster charge transfer rate and higher doping levels by differential pulse voltammetry (DPV), Chronocoulometry and X-ray photoelectron spectroscopy (XPS) analysis. Rutin could be detected in the concentration range of 0.5 nM to 1 μM, and 5 to 50 μM with the low detection limit as 0.24 nM (S/N = 3). Moreover, MIP/1.7 exhibited 3-fold increase current response toward rutin by DPV when compared with the corresponding non-imprinted polymer (NIP), revealing the success of the imprinting. This sensor also exhibited high selectivity, good long-term stability, and acceptable reproducibility. The rutin content in Flos Sophorae Immaturus (FSI) was 25.37% with good accuracy.