Amine-Grafted Graphene Oxide Functionalized With N,S-Doped Carbon Dots: Sensitive Electrochemical Sensor for Metronidazole Determination

A selective electrochemical platform for metronidazole was developed by modification of a glassy carbon electrode (GCE) with N,S-doped carbon dots (N,S-CDs) and amine-grafted graphene oxide (GONH2) nanohybrid. After modification of graphene oxide with (3-aminopropyl)triethoxysilane, the resulting GONH2 was covalently functionalized with N,S-CDs by an easy and inexpensive hydrothermal method. To achieve this purpose, GONH2, citric acid, and thiourea were used as the precursors. For the functionalization of GONH2 with N,S-CDs, thiourea was used as a source of N and S atoms in the hydrothermal method. The N,S-CDs/GONH2 were utilized for the GCE modification that was evaluated by spectroscopic and microscopic methods. The electrochemical techniques were then used for the measurement of metronidazole. The GCE/N,S-CDs/GONH2 provided a higher peak current than the bare GCE or GCE/GONH2 for the electroreduction of metronidazole originated from the synergetic role of the GONH2 and N,S-CDs, and the expanded surface area. The detection limit obtained for metronidazole in the concentration span of 0.05–
$100 ~\mu \text{m}$
was equal to 10 nm. In addition to good reproducibility and stability, the GCE/N,S-CDs/GONH2 accurately measure metronidazole in natural specimens with a recovery percentage of 90%–97%.