Highly efficient nanofibrous sterile membrane with anti-BSA/RNA-fouling surface via plasma-assisted carboxylation process

Constructing a functional porous membrane scaffold for the efficient separation of bacteria from protein and nucleic acid drug stock solution remains a great challenge due to the permeability-selectivity trade-off and fouling propensity of membranes. Here, we adopted the nanofiber suspension coating approach to prepare sterile membrane with nanofiber coverage density of 6 g/m2. The carboxylation surface was further achieved through a facile route including alkaline solution activation and low temperature plasma treatment in sequence. As indicated by experimental and theoretical model analysis, nanofibrous membrane treated by alkali and plasma (NFM-APT) possess an ultrathin nanofiber active layer (about 4.7 μm), narrow pore size distribution (average size: 0.1 μm) and high hydrophilicity, which is beneficial for the absolute interception of E. coli, S. aureus and B. diminuta as well as a relative high and stable permeability (7400.4 L/(m2h), 0.2 MPa). Moreover, NFM-APT presents ultralow adsorption of BSA and RNA in the test of continue-flow and static-immersion modes with an excellent reusability after back-washing process, which is superior to the nascent nanofibrous membrane and commercially available PES membrane. The extraordinary anti-BSA/RNA-fouling performance can be attributed to the excellent hydrophilicity of membrane as well as the robust repulsive interaction between the negatively charged carboxyl group grafted on the surface of fiber and the negatively charged BSA&RNA. The NFM-APT also possesses outstanding performance stability, easy operation, and excellent recoverability. This work may provide a new avenue to design and develop next-generation high-performance sterile membrane for bio-separation.