A novel graphene oxide-1,3,4-oxadiazole-2,5-diamine nanomaterial with enhanced bactericide activity

Abstract

BackgroundThe development of effective nanomaterials is becoming important to safeguard the human health from the bacteria-induced infectious diseases. Among the popular nanomaterials, graphene oxide (GO) owns functional groups and exhibits noticeable benefits which are helpful for biological applications. For raising the antibacterial activity with the reinforcement of the active organic molecules like oxadiazoles, a novel GO-1,3,4-oxadiazole-2,5-diamine (ODA) nanomaterial was prepared and characterized for the first time in our study. MethodsGO-diamine nanomaterials were synthesized by simply reacting GO with ODA or aliphatic diamine in a water bath at room temperature. In an in vitro antimicrobial activity investigation, 5 mg of the nanomaterial was immersed in 20 mL of the Escherichia coli culture in agar media at 37 °C, and the growth of bacteria was evaluated after 24 h. Significant FindingsBy XRD analysis, it was found that the increase in d-spacing after the intercalation of aliphatic diamine into GO layers was close to the molecular length of aliphatic diamine, indicating a perpendicular bridging configuration. Conversely, the aromatic ODA reacted with the oxygenated functionalities on the outer surface of GO layer and a free amine was left behind in the terminal. In the bactericide activity test, a near complete E. coli inhibition was achieved only with GO-ODA, much better than pure ODA (30–60 %) and pristine GO (0–20 %). The pure aliphatic diamines showed some extent of antibacterial activity (20–60 %) due to their natural toxicity, but their GO-aliphatic diamine derivatives demonstrated negligible bactericide activity (0–10 %). Conclusively, this study provides a greener and effective antibacterial material without using any catalyst or organic solvent.