Effect of Network Topology on the Protein Adsorption Behavior of Hydrophilic Polymeric Coatings

We prepared polyurethane (PU) network coatings with various cross-linking densities that were based on polypropylene glycol (PPG) and polytetramethylene glycol (PTMG) macrodiols with different lengths and containing similar amounts of hydrophilic methoxy polyethylene glycol (mPEG) dangling chains. Then, we investigated the effect of the network cross-linking density on the coating-water interface and protein adsorption through coarse-grained (CG) molecular dynamics (MD) simulations and experimental studies on molecular and macroscopic scales. Our CG MD simulations reveal that although a higher cross-linking density provides more connecting sites for hydrophilic dangling chains in the PU network, it diminishes the orientation of the hydrophilic dangling chains toward the water interface. Besides, our experimental results confirm that tighter networks with a similar total mPEG content display lower hydrophilicity (larger advancing water contact angle), a lower amount of mPEG migration to the interface (lower surface roughness measured by atomic force microscope), and higher human serum albumin and human fibrinogen adsorption, in agreement with CG MD simulation results.