Surface functionalization using two-dimensional (2D)
graphene oxide
(GO) materials is a promising technique to enhance the biofouling
resistance of membranes used in water purification and reuse. However,
the role of GO exposure, which is crucial for the contact-mediated
toxicity mechanism, has not been well evaluated or elucidated in previous
studies. Herein, we employ bioinspired polydopamine chemistry to fabricate
GO-functionalized membranes through two strategies: coating and blending.
The two types of GO-functionalized membranes displayed comparable
roughness, hydrophilicity, water permeability, and solute retention
properties but different degrees of GO nanosheet exposure on the membrane
surface. When in contact with the model bacterium, Escherichia coli, the GO-coated membrane exhibited
enhanced biofouling resistance compared to that of the GO-blended
membrane, as evidenced by lower viable cells in static adsorption
experiments, and lower water flux decline and higher flux recovery
in dynamic biofouling experiments. Moreover, the development of biofilm
on the GO-coated membrane was also inhibited to a greater extent than
on the GO-blended membrane. Taken together, our findings indicate
the paramount importance of GO exposure on the membrane surface in
conferring antibacterial activity and biofouling resistance, which
should be considered in the future design of antibiofouling membranes
using 2D nanomaterials.