Ultra-sensitive amperometric determination of quercetin by using a glassy carbon electrode modified with a nanocomposite prepared from aminated graphene quantum dots, thiolated β-cyclodextrin and gold nanoparticles.

Thiolated β-cyclodextrin functionalized gold nanoparticles (Au-β-CDs) with layered wrinkled flower structure were prepared. Au-β-CDs were electrostatically combined with protonated aminated graphene quantum dots (NH2-GQDs) to form a nanocomposite with better supramolecular recognition, conductivity, catalysis and dispersion properties. For constructing a quercetin (QU) sensor, the nanocomposites were one-step electrodeposited by a cyclic voltammetry (CV) method onto a glassy carbon electrode to form a stable film. Under optimized conditions, the sensor showed a wide linear response range of 1-210 nM, with a lower detection limit of 285 pM. At the same time, flavonoids with similar structures hardly interfere with the determination of QU. The sensor has been used to determine QU in honey, tea, honeysuckle and human serum with satisfactory results. Graphical abstractSchematic representation of the fabrication of an ultrasensitive quercetin electrochemical sensor based on aminated graphene quantum dots, thiolated β-cyclodextrin and gold nanoparticles (NH2-GQDs/Au-β-CD/GCE).