(65e) Investigating Reactive Oxygen Species of Chitosan-Graphene Oxide Composites for Water Treatment Membranes

Graphene oxide (GO) is a promising candidate material for antimicrobial membranes due to oxidative debris (OD) that can serve as reactive oxygen species (ROS) generation sites. However, the underlying mechanisms of oxidation have not been resolved. This study demonstrates the role of the superoxide radical (O2- •) in the oxidative properties of GO, coupled with the electrostatic interactions of cationic chitosan (CS) in GO composite membranes (CSGO). Biofilm studies confirm growth inhibition is attributed to both contact-based physical interactions coupled with oxidative stress in a “trap and treat” mechanism. Bacteria applied to the surface of the CSGO composite were unable to thrive on the material, thus indicating that its surface was an unfavorable environment for cell growth instigating interruptions in vital cellular processes due to stress on the membrane from interactions with GO materials. Both superoxide dismutase (SOD) assay and electron spin resonance (ESR) confirmed the generation of the ROS, superoxide. The oxidation of glutathione (GSH) confirms the presence of superoxide at levels capable of inducing oxidative stress. The synergistic mechanisms of CSGO produce a viable antimicrobial platform for a broad spectrum of pathogens present in environmental and wastewater applications. For water treatment, production of reactive oxygen species originating from GO containing OD with oxygen based functional groups from the CSGO composite can further discourage biofouling from bacteria overgrowth. Due to scalability and performance of the CSGO composite for both bacterial entrapment and cellular inhibition make this material an attractive option as an antifouling membrane in water treatment applications. The results demonstrate that the composites fabricated in this study can be utilized in the future to inactivate pathogens in the medical, food processing, and water treatment industries as well as in the field of environmental remediation.