A novel molecularly imprinted electrochemical sensor modified with carbon dots, chitosan, gold nanoparticles for the determination of patulin

In this paper, molecular imprinting technique was applied to the electrochemical sensor. We used 2-oxindole as dummy template, ρ-Aminothiophenol (ρ-ATP) as functional monomers, combined with the high sensitivity of electrochemical detection, to achieve a specific and efficient detection of patulin in fruit juice. In addition, carbon dots and chitosan were used as the modifying material to improve electron-transfer rate, expand the electroactive surface of glassy carbon electrode and enhance strength of the signal. The Au–S bond and hydrogen bond were employed to complete the assembly of the ρ-ATP and 2-oxindole on the surface of the electrode. Then, polymer membranes were formed by electropolymerization in a polymer solution containing ρ-ATP, HAuCl4, tetrabutylammonium perchlorate (TBAP) and the template molecule 2- oxindole. After elution, the specific cavity can adsorb the target patulin. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were performed to monitor the electropolymerization process and its optimization. Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) analyses were used for characterization. This was the first time that the molecularly imprinted polymer (MIP) technology combined with carbon dots, chitosan and Au nanoparticles modification and was applied in the electrochemical detection of patulin. The linear response range of the MIP sensor was from 1 × 10–12 to 1 × 10−9 mol L−1 and the limit of detection (LOD) was 7.57 × 10–13 mol L−1. The sensor had a high-speed real-time detection capability, low sample consumption, high sensitivity, low interference, good stability and could become a new promising method for the detection of patulin.