Molecularly imprinted electrochemical sensor for ultrasensitive detection of quercetin in grapes and derived products

A dual-functional membrane modified electrode - based molecularly imprinted electrochemical sensor was developed for the ultrasensitive and selective detection of quercetin (Que). The dual-functional membrane consisted of chitosan-modified carboxylated multi-walled carbon nanotubes (cMWCNT-CS) nanocomposites and β-cyclodextrin/dopamine molecularly imprinted polymer (β-CD-DA-MIP). The synergistic interactions between the conductive layer of cMWCNT-CS and the recognition element of β-CD-DA-MIP enabled high-performance detection of Que. This sensor exhibited an ultra-wide linear response range of 1.0 × 10 −14 to 1.0 × 10 −4  M with a limit of detection of 2.9 × 10 −16  M (S/N = 3). The sensor also had the advantages of simple fabrication, rapid response (6 min), excellent reproducibility, and high selectivity. The sensor was successfully used to detect Que. concentration in grape, grape juice, and wine samples with satisfactory results. This study provided a simple, efficient, and ultrasensitive method for monitoring the natural bioactive compounds, which offered potential applications for food quality control and pharmaceutical analysis.