One-step fabrication of electrochemical biosensor based on DNA-modified three-dimensional reduced graphene oxide and chitosan nanocomposite for highly sensitive detection of Hg(II)

A novel DNA-modified nanocomposite of three-dimensional reduced graphene oxide and chitosan particles (CS@3D-rGO@DNA) was prepared by one-step method and used as a new electrochemical bio sensing strategy to detect Hg2+ in drinking water. This biosensor was fabricated by the chemical coordination of T-Hg2+-T between the T-rich oligonucleotide strands contained in the as-prepared CS@3D-rGO@DNA nanocomposite and Hg2+, thereby varying the electrochemical signals. The developed electrochemical biosensor exhibited high sensitivity toward the determination of Hg2+ with a low detection limit of 0.016 nM, ranging from 0.1 nM to 10 nM. This novel bio sensor also showed high selectivity, good stability, and repeatability. Hence, this proposed CS@3D-rGO@DNA-based electrochemical strategy is feasible and may offer a simple, rapid, cost-effective, highly selective, and sensitive method for Hg2+ quantification. (C) 2015 Elsevier B.V. All rights reserved.