An Electrochemical Nanosensor Based on Molecularly Imprinted Polymer (MIP) for Detection of Gallic Acid in Fruit Juices

The molecularly imprinted polymer (MIP)-based electrochemical sensor has been attending recently, due to their exceptional advantages and specificity. Here, we successfully designed and fabricated a novel electrochemical nanosensor for determination of gallic acid (GA) based on its specific MIP. The MIP was synthesized using precipitation polymerization technique, via polymerization of methacrylic acid as a functional monomer. The MIP was applied in the multiwalled carbon nanotube-modified carbon paste electrode (MWCNT–CPE), and similarly, MIP and MWCNT-modified CPE (MIP–MWCNT–CPE) was prepared, which acted as the selective recognition element and pre-concentrator agent for GA. The effect of different factors such as quantity of MIP and MWCNT, GA solution pH, and GA accumulation time on an oxidation current of accumulated GA at the electrode were investigated and optimized by central composite design (CCD) as a an experimental design and response surface methodology. The results showed that fabricated nanosensors (MIP–MWCNT–CPE) have higher sensitivity compared with bare CPE, MWCNT–CPE, and MIP–CPE. This sensor showed a linear response range of 0.12–380.0 μM and detection limit of 47.0 nM. Finally, the nanosensor was applied to determine GA in apple, pineapple, orange juices, and a commercial green tea drink as real samples with satisfactory results.