Protein Fouling Characteristics of Graphene Oxide Membranes

Advancing the knowledge of surfaces and protein interactions is paramount to development of non-fouling membranes for many applications, particularly continuous blood flow wearable and implantable devices. Here, highly controlled experiments to understand the effect of graphene oxide (GO) surface properties on its protein adsorption are presented. A newly developed self-assembly process is implemented to build a GO membrane with an atomically smooth surface to eliminate the effect of surface roughness on protein adsorption. The GO oxidation level is varied to change the overall membrane hydrophilicity while the nanoplatelets size and edge area is maintained constant. The fouling characteristics of the membrane are examined through scanning electron microscope imaging and long-term water flux measurements. These measurements unambiguously prove that proteins are primarily adsorbed on the basal areas of nanoplatelets, on the graphitic regions, away from the nanoplatelets edges. As a result, while decreasing the oxidation level reduced the overall surface hydrophilicity leading to more protein adsorption, the membrane mass flux is minimally impacted. Studies on a polymer membrane under similar conditions show expansion of protein agglomerates over time leading to formation of large biofilm domains, while the GO nanoplatelets edges function as a barrier to formation of an expansive biofilm.