A graphene oxide/silver nanoparticle composite as a novel agricultural antibacterial agent against Xanthomonas oryzae pv. oryzae for crop disease management

Bacterial leaf blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most destructive diseases in the growth and development of rice (Oryza sativa L.). Various chemical biocides have been used to manage this disease, which has led to residual contamination in rice, resistance among the Xoo and significant risks to human health. Here, a graphene oxide/silver nanoparticle (GO-Ag) composite was developed and its antibacterial properties against Xoo were also investigated. The results indicated that the GO-Ag composite displayed almost a four-fold enhancement as compared to that of pure Ag NPs. The bacteria were completely inactivated at a relatively low concentration of 2.5 mu g mL(-1). At the cellular level, the integrity of the cell was damaged and the intercellular contents leaked out by slow-releasing of silver ions from the GO-Ag composite. At the molecular level, this composite induced the production of reactive oxygen species and inhibited DNA replication. More importantly, the phytotoxicity test demonstrated that the as-prepared GO-Ag composite had lower toxicity for the plants than Ag NPs, making it a potential candidate for application in crop disease prevention.