Electrochemical biosensor based on three-dimensional reduced graphene oxide and polyaniline nanocomposite for selective detection of mercury ions

Nanorod-like nanocomposite of three-dimensional reduced graphene oxide and polyaniline (3D-rGO@PANI) was synthesized via an in situ chemical oxidative polymerization method and was then used as the sensitive layer of a DNA adsorbent for detecting Hg 2+ in aqueous solution. Amino-group-rich 3D-rGO@PANI exhibited high affinity toward the immobilization of T-rich DNA strands, which preferred to bind with Hg 2+ to form T Hg 2+ T coordination. Electrochemical impedance spectroscopy was applied to determine the difference in the electrochemical performances during Hg 2+ detection. The results demonstrated that the electrochemical biosensor based on 3D-rGO@PANI nanocomposite showed high sensitivity and selectivity toward Hg 2+ within a concentration range from 0.1   nM to 100   nM with low detection limit of 0.035   nM. The proposed nanosensor could be applied for highly sensitive and selective determination of heavy metal ion in various environmental detections.