Zwitterion-Conjugated\nProtein Coatings for Enhanced\nAntifouling in Complex Biofluids: Underlying Molecular Interaction\nMechanisms

Biofouling can cause severe infections, device malfunctions,\nand\nfailures in diagnostics and therapeutics. Proteins such as bovine\nserum albumin (BSA) have recently been used as coatings to resist\nbiofouling because they combine surface anchoring and antifouling\nproperties. However, their antifouling effectiveness will significantly\ndeteriorate in complex biofluids with high salinity, limiting their\npractical applications. In this work, we developed a zwitterion-conjugated\nprotein with enhanced antifouling capability by grafting zwitterionic\n2-methacryloyloxyethyl phosphorylcholine (MPC) onto BSA protein via\na click reaction. This conjugated protein can easily anchor on various\nsubstrates, both inorganic and organic, and exhibits efficient and\nbroad-spectrum fouling resistance to metabolites, proteins, and complex\nbiofluids. Even in the complex fetal bovine serum with higher salinity,\nthe BSA@MPC coating can also maintain 99% fouling resistance robustly,\nover 6-fold superior to native BSA-coated surfaces in antifouling\ncapability. Direct surface forces measurement reveals that such outstanding\nantifouling properties of conjugated protein BSA@MPC could be attributed\nto the stable hydration layer on its surface and the steric repulsion\nfrom the antipolyelectrolyte behavior of zwitterionic MPC polymer\nin the high-salinity environment. Our findings advance the development\nof protein-based functional materials and provide valuable insights\nfor designing novel antifouling surfaces for marine, food, and bioengineering\napplications.