Engineering graphene/quantum dot interfaces for high performance electrochemical nanocomposites in detecting puerarin

CdTe quantum dots (QDs) capped by 1-ethyl-3-methylimidazolium mercaptopropionate ([emim]MP) and the reduced graphene oxide (RG) modified by the amine-terminated ionic liquid ([amim]Br) were synthesized in this work. The coordinating interface interactions between QD and RG render the nanocomposite the excellent electrochemical performances as revealed by cyclic voltammetry, chronocoulometry, and electrical impedance spectroscopy. Based on the experimental results obtained from amimRG, CdTe@MP-amimRG, CdTe@[bmim]MP-amimRG, and CdTe@[emim]MP-amimRG nanocomposites, it is proposed that the synergistic effects between imidazolium rings and graphene are responsible for the enhanced performances. Taking the CdTe@[emim]MP-amimRG nanocomposite as the electrochemical sensor of puerarin, the proposed method demonstrates the linear range over 0.01-4.0 μmol L−1 with the detection limits of 6 nmol L−1 in the aqueous solution (S/N = 3). Moreover, the sensor exhibits fast response time (2s), high sensitivity (74.57 μA μmol L−1 cm−2), as well as reproducibility (RSD ≤ 8%), and can maintain the stability at 4 °C for two weeks.