Fabrication of surface molecularly imprinted electrochemical sensor for the sensitive quantification of chlortetracycline with ionic liquid and MWCNT improving performance

Chlortetracycline (CTC) is a widely used broad-spectrum antibiotic, its residue likely occurs in the environment and foods, bringing some negative effects to human health. Hence the detection and quantification of CTC in environmental and food samples is relevant. Herein, a novel electrochemical sensor based on surface molecularly imprinted polymer (SMIP) was constructed for the quantitative detection of CTC. The SMIP was synthesized by using ionic liquid (IL) functionalized MWCNT (MWCNT-IL) as supporter, 1-carboxymethyl-3-vinylimidazolium bromide (IL1) as functional monomer, CTC as template, ethylene glycol dimethyl acrylate as crosslinker, and azobisisobutyronitrile as initiator. The obtained composite IL1-SMIP exhibited high adsorption capacity for CTC and the imprinting factor was ca. 4.1. It was found that IL played an important role in improving the property of SMIP, which was also evaluated by DFT-based calculation. The resulting sensor IL1-SMIP/MWCNT-IL/GCE showed high selectivity, sensitivity and reproducibility. CTC could be quantified from 0.4 μM to 55 μM with a detection limit of 0.08 μM (S/N = 3) under the optimized conditions. The practical applicability of the sensor was demonstrated successfully by determining CTC in real samples.