COMPARISON OF ANTIBACTERIAL ACTIVITY OF GRAPHEN OXIDE- SILVER NANOCOMPOSITE SYNTHESIZED BY TWO DIFFERENT GREEN APPROACHES

Background and Aim:There are many disagreements on the antibacterial behavior of Graphene Oxide (GO). However, GO was used as an ideal substrate for tethering metal nanoparticles to overcome their drawbacks, because of its unique properties, such as biocompatibility. Hence, exploration of the antibacterial properties of graphene-based nanocomposites has been one of the most important research fields.Methods:In this study, Ag-GO nanocomposites were green synthesized by using Walnut extract at two different approaches: 1) GO + silver nitrate + extract, and 2) GO + extract + silver nitrate. Physicochemical properties of the final products were characterized by UV-Vis, FT-IR, XRD, and FE-SEM. Subsequently, the antibacterial activity of the products was assessed on both gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacterial strains and their activity compared with silver nanoparticles and Tetracycline.Results:According to the results, GO did not reveal any antibacterial activity and Tetracycline had high activity only against S. aureus. Moreover, Antibacterial activity of products could be summarized as AgNPs ˃ nanocomposite 2 ˃ nanocomposite 1. In the both of the approaches, AgNPs were well dispersed on GO sheets. However, FE-SEM pictures revealed that in approach 1, AgNPs are placed between GO sheets. While in approach 2, AgNPs covere the surface of sheets. Therefore, it seems at approach 2 AgNPs decorated on GO sheets had more interaction with bacterial cells than approach 1 products.Conclusion:It is concluded that the composition of AgNPs and GO could lead to controlled antibacterial activity and their stability, depending on the synthetic approach.

Keywords:

Silver nanoparticles , Graphene Oxide , Nanocomposite , Antibacterial Agent