Resolving the Effects of Hydration and Salt Bridges on Protein Adhesion Resistance of Zwitterionic Polymer Brushes via AFM/MD

Zwitterionic polymer brushes have received much attention due to their excellent antiprotein adhesion properties. However, there is a lack of clarity on the origin of the protein adhesion resistance of polymer brushes and the correlation between protein adhesion resistance and structure. In this study, the interaction force between poly methacryloyl ethylsulfobetaine (PSBMA) brushes and proteins was subjected to a comprehensive and systematic analysis employing atomic force microscopy (AFM) and molecular dynamics simulation (MD). The findings demonstrated that the modified PSBMA brushes markedly diminished protein adhesion to the surface in AFM tests. Protein adhesion decreased with increasing graft density, with the highest reduction in protein adhesion exceeding 95%. Molecular dynamics simulations demonstrated that an increase in grafting density resulted in a reduction in the number of salt bridges between proteins and polymer brushes and an enhancement in the hydration repulsion of the polymer brushes. These combined effects led to a decline in protein adhesion. This study reveals, at the atomic level, that the antiprotein adhesion properties of PSBMA brushes are structure-dependent, thereby providing valuable guidance for the design and development of more effective antiadhesion polymer brush coatings.