Protein Resistant Property of Nanometer-Scale Architecture of Polymer Chains

We recently reported that a few nanometer-thick polymer layer formed on a solid, which consists of physisorbed non-charged homopolymer chains, exhibits anti-fouling properties against a model protein, bovine serum albumin (BSA), independent of polymer hydrophilicity/hydrophobicity[1]. We revealed that the highly packed chain architecture plays a crucial role in its protein resistant property over surface chemistry. Here, we further illuminate how this nanometer-scale chain structure impacts the protein adsorption on ultrathin polymer films. Polymer films with different thicknesses ranging from 2 nm to 200 nm of polystyrene, poly(2-vinyl pyridine), polybutadiene, poly(methyl methacrylate), and polypropylene were prepared. Adsorption of fluorescein labeled BSA and fibrinogen on these thin films were studied as a function of film thickness using photon counting spectrofluorometry. We observe that the critical thickness of the adsorption transition from anti-fouling to fouling appeared irrespective of the type of polymers and proteins. In addition, molecular dynamics simulations were performed to mimic the protein adsorption process. We will discuss the mechanism behind the phenomenon.
[1] Endoh et al., ACS Macro Lett. 2019, 8, 1153.