Drastically Lowered Protein Adsorption on Microbicidal Hydrophobic/Hydrophilic Polyelectrolyte Multilayers

Abstract

Polyelectrolyte multilayer films assembled from a hydrophobic N-alkylated polyethylenimine and a hydrophilic polyacrylate were discovered to exhibit strong antifouling, as well as antimicrobial, activities. Surfaces coated with these layer-by-layer (LbL) films, which range from 6 to 10 bilayers (up to 45 nm in thickness), adsorbed up to 20 times less protein from blood plasma than the uncoated controls. The dependence of the antifouling activity on the nature of the polycation, as well as on assembly conditions and the number of layers in the LbL films, was investigated. Changing the hydrophobicity of the polycation altered the surface composition and the resistance to protein adsorption of the LbL films. Importantly, this resistance was greater for coated surfaces with the polyanion on top; for these films, the average zeta potential pointed to a near neutral surface charge, thus, presumably minimizing their electrostatic interactions with the protein. The film surface exhibited a large contact angle hysteresis, indicating a heterogeneous topology likely due to the existence of hydrophobic-hydrophilic regions on the surface. Scanning electron micrographs of the film surface revealed the existence of nanoscale domains. We hypothesize that the existence of hydrophobic/hydrophilic nanodomains, as well as surface charge neutrality, contributes to the LbL film's resistance to protein adsorption.

Superior Antifouling Performance of a Zwitterionic Peptide Compared to an Amphiphilic, Non-Ionic Peptide

“…These results suggest that both peptides likely adopt a disordered, random configuration on the Au surface. [43][44] A similar result was also observed previously with an EKEKEKE-C peptide. 34 In addition to the secondary structure, the zeta potentials of the CRERERE peptide were also measured at different pH values to confirm its zwitterionic property.…”

Multimonth controlled small molecule release from biodegradable thin films

“…Investigations into tuning of proteolytic susceptibility have shown that although some human proteases have poor activity against LbL films (63), film characteristics including covalent cross-linking (64), L-or D-polypeptides (65), and terminal layer charge (66), among others, can enhance or inhibit degradation. In addition, antifouling modifications like PEGylation (67) and mixed-charge nanodomains (68) can introduce a protein resistance that reduces enzyme contact with the film. This versatility in LbL-assembled films, coupled with the nonenzymatic hydrolytic release mechanism, can readily accommodate a variety of modifications that specifically tune film characteristics to the desired application.…”

Polyelectrolyte Multilayers on Silica Surfaces: Effect of Ionic Strength and Sodium Salt Type

“…On the other hand, Wong and coworkers showed that the protein adsorption is drastically lowered on microbicidal hydrophobic/hydrophilic polyelectrolyte multilayers. [18] It was shown recently [19] that that the extent of adhered bacteria mostly depends on the type of terminating polyelectrolyte layer, although surface roughness and hydrophobicity should be also taken into account.…”