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 biosensing strategy to detect Hg 2+ in drinking water . This biosensor was fabricated by the chemical coordination of T-Hg 2+ -T between the T-rich oligonucleotide strands contained in the as-prepared CS@3D-rGO@DNA nanocomposite and Hg 2+ , thereby varying the electrochemical signals. The developed electrochemical biosensor exhibited high sensitivity toward the determination of Hg 2+ with a low detection limit of 0.016   nM, ranging from 0.1   nM to 10   nM. This novel biosensor 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 Hg 2+ quantification.