▎ 摘　　要

The occurrence of multidrug resistance (MDR) has become a major obstacle to the successful performance of chemotherapy for cancer patients, so it is highly required to develop methods to explore the new strategy to early diagnose the MDR. Here, we report a novel label-free electrochemical DNA biosensor for simple, effective and convenient determination of MDR1 gene based on Au nanoparticles/toluidine blue-graphene oxide (Au NPs/TB-GO) modified electrode. The resulting Au NPs/TB-GO nanocomposites were characterized by scanning electron microscopy, atomic force microscope, ultraviolet-visible spectrometry, cyclic voltammetry, and electrochemical impedance spectroscopy. Differential pulse voltammetry was employed to monitor the hybridization of DNA by measuring the changes in the peak currents of TB. Under optimal conditions, the decreased currents were proportional to the logarithm of the concentration of the target DNA in the range of 1.0 x 10(-11)-1.0 x 10(-9) M with a detection limit of 2.95 x 10(-12) M (at an S/N of 3). In addition, the biosensor exhibited good selectivity, acceptable stability and reproducibility. The proposed method was simple, fast and inexpensive for the determination of MDR1 gene at low levels. (C) 2014 Elsevier B.V. All rights reserved.