A simple and sensitive sensor based on a molecularly imprinted polymer-modified carbon paste electrode for the determination of curcumin in foods

A highly sensitive and selective molecularly imprinted polymer-modified carbon paste electrode (MIP-CPE) was designed. The curcumin molecularly imprinted polymer (CUR-MIP) was prepared by thermally induced precipitation polymerization, using curcumin (CUR) as the template molecule, methacrylic acid (MAA) as the functional monomer, 2,20-azodiisobutyronitrile (AIBN) as the initiator, and ethylene glycol dimethacrylate (EDGMA) as the cross-linker. The modified electrode was prepared by mixing the polymer, graphite powder, and paraffin oil in specific proportions. The electrochemical behaviour of CUR on this electrode was studied, and a method for direct CUR determination using this electrode was established. The results showed that CUR exhibited a distinct oxidation peak (Epa) at 0.434 V (vs. SCE) in the mixed phosphate buffer solution (PBS) at pH 3.06. The optimum addition ratio of the polymer in the modified electrode was 20%, and the peak current (Ipa) was 4.5-fold higher than that of the bare CPE. The Ipa showed a good linear relationship with concentration in the range 0.1-50 mu M, and the detection limit was 10.1 nM. The method was applied to determine CUR contents in food, giving recovery rates of 90.77-105.7%.