Protein Interaction with Zwitterionic Spherical Polyelectrolyte Brushes as Observed by Small Angle X-ray Scattering

Understanding how zwitterionic spherical polyelectrolyte brushes (SPB) fulfill their antifouling functions requires knowledge of their interactions with exogenous nanoparticles, such as proteins. In this study, zwitterionic SPB were synthesized by grafting 3-[(2-(methacryloyloxy)ethyl)dimethylammonio]propanoate (CBMA) and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) onto a polystyrene core via photoemulsion polymerization. Small-angle X-ray scattering was employed to elucidate the interactions and protein adsorption behaviors of the zwitterionic SPB and proteins. SAXS results revealed that both PCBMA SPB and PSBMA SPB exhibit minimal protein adsorption compared with cationic and anionic SPB. PSBMA SPB maintained a consistent resistance to protein adsorption across various conditions. However, PCBMA SPB demonstrated tunable protein adsorption properties, enabled by the controllable ionization of carboxyl groups on the brush chains while maintaining consistently low overall adsorption. These insights enhance our understanding of zwitterionic SPB and offer an experimental and theoretical basis for their application in biomaterials and antifouling technologies.