▎ 摘　　要

In this paper a new electrochemical DNA biosensor was prepared by using graphene (GR) and nickel oxide (NiO) nanocomposite modified carbon ionic liquid elctrode (CILE) as the substrate electrode. GR and NiO nanoparticles were electrodeposited on the CILE surface step-by-step to get the nanocomposite. Due to the strong affinity of Ni0 with phosphate groups of ssDNA, oligonucleotide probe with a terminal 5'-phosphate group could be attached on the surface of NiO/GR/CILE, which could further hybridize with the target ssDNA sequence; Methylene blue (MB) was used as the electrochemical indicator for monitoring the hybridization reaction. Under the optimal conditions the reduction peak current of MB was proportional to the concentration of salmonella enteritidis gene sequence in the range from 1.0 x 10(-13) to 1.0 x 10(-6) mol L-1 with a detection limit as 3.12 x 10(-14) mol L-1. This electrochemical DNA sensor exhibited good discrimination ability to one-base and three-base mismatched ssDNA sequences, and the polymerase chain reaction amplification product of salmonella enteritidis gene sequences were further detected with satisfactory results. (C) 2014 Elsevier B.V. All rights reserved.