In this study, we developed a hybrid biosensor composed of reduced graphene oxide (rGO) sheets decorated with gold nanoparticles (Au NPs) for sequence-specific DNA detection. The DNA probe (HS-DNA) was covalently linked to the surface of Au NPs/rGO via an Au-S bond, and scanning electron microscopy and electrochemical impedance spectra were used to the assemble the electrode surface. Furthermore, differential pulse voltammetry was utilized to monitor the DNA hybridization event by measuring the changes in peak current of the intercalated adriamycin. The peak currents of adriamycin were linear with the concentration of complementary DNA, which ranged from 1.0 x 10(-8) to 1.0 x 10(-13) mol dm(-3) with a detection limit of 3.5 x 10(-14) mol dm(-3) (signal/noise ratio of 3) under the optimal conditions. Moreover, the complementary DNA sequence was detected in the presence of a large amount of three-base mismatched DNA (1000:1), which indicates that the biosensor has high selectivity. (C) 2012 Elsevier Ltd. All rights reserved.