A novel quercetin electrochemical sensor based on molecularly imprinted poly(para-aminobenzoic acid) on 3D Pd nanoparticles-porous graphene-carbon nanotubes composite

A novel molecularly imprinted electrochemical sensor for quercetin (QR) was fabricated via electropolymerization of para -aminobenzoic acid (p-ABA) on a three-dimensional (3D) Pd nanoparticles-porous graphene-carbon nanotubes composite (Pd/pGN-CNTs) modified glassy carbon electrode. The 3D Pd/pGN-CNTs composite was prepared by a facile one-pot hydrothermal method and it exhibited high conductivity, large surface as well as excellent electrocatalysis. The imprinting factor (IF) of MIP sensor toward QR was 3.14, which is higher than those of its analogues (i. e. morin, catechin, rutin, luteolin, and kaempferide). Based on the synergistic effect of the nanocomposite and the molecularly imprinted poly(p-ABA), the resulting electrochemical sensor presented high sensitivity and selectivity. Its linear response range was 0.01–0.50   μM, and the low detection limit was 5.0   nM (S/N   =   3). The sensor also showed good reproducibility and stability. It was successfully applied to the detection of QR in food and medicine samples. In addition, theoretical calculations based on density functional theory (DFT) was conducted, and the result indicated that there was strong hydrogen bond between the QR and p-ABA.