▎ 摘　　要

A novel, ultra-sensitive and selective sensing platform was fabricated for detection of tryptophan (Trp) based on beta-cyclodextrin modified magnetic graphene oxide (MGO-CD) nanocomposites. Magnetic Fe3O4 modified graphene oxide (MGO) was prepared by a simple coprecipitation method, then beta-CD was conjugated on the surface of MGO through strong hydrogen bond and hydrophobic interaction. The sensitivity was obviously improved due to the synergistic effects between Fe3O4 and graphene oxide (GO), which would enhance the electron transfer rate as well as increase the surface area to capture a large amount of beta-CD. Furthermore, the graft of beta-CD had strong recognition capability for Trp to form stable host-guest inclusion complexes leading to the promotion of selectivity. The MGO-CD modified glassy carbon electrode (MGO-CD/GCE) was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and it revealed extraordinary electrochemical response towards the determination of Trp. Under the optimized conditions, the electrochemical sensor showed a wide linear range from 5.0 x 10(-7) M to 7.5 x 10(-4) M with a low detection limit of 3.1 x 10(-7) M (S/N = 3). The proposed method displayed good reproducibility and excellent stability, which could be validated for commercial amino acid preparation sample, and satisfactory results were received. This strategy might provide the new clue for the clinic application. (C) 2016 Elsevier B.V. All rights reserved.