Temperature-Activated PEG Surface Segregation Controls the Protein Repellency of Polymers

Abstract

Poly(ethylene glycol) (PEG) is widely used to modulate the hydration states of biomaterials and is often applied to produce non-fouling surfaces. Here, we present X-ray scattering data which show that it is the surface segregation of PEG, not just its presence in the bulk, that makes this happen by influencing the hydrophilicity of PEG-containing substrates. We demonstrate a temperaturedependent trigger that transforms a PEG-containing substrate from a protein-adsorbing to a protein-repelling state. On films of poly(desaminotyrosyl-tyrosineco-PEG carbonate) with high (20 wt %) PEG content, in which very little protein adsorption would have been expected, quartz crystal microbalance (QCM) data showed significant adsorption of fibrinogen (Fg) and bovine serum albumin (BSA) at 8 °C. The surface became protein-repellent at 37.5 °C. When the same polymer was iodinated, the polymer was protein adsorbent, even when 37 wt % PEG was incorporated into the polymer backbone. This demonstrates that high PEG content by itself is not sufficient to repel proteins. By inhibiting phase separation either with iodine or by lowering the temperature, we show that PEG must phase separate and bloom to the surface in order to create an antifouling surface. These results suggest an opportunity to design materials with high-PEG content that can be switched from a protein-attractant to a protein-repellent state by inducing phase separation through a brief exposure to temperatures above their glass transition temperature.

Single-Molecule Detection of Nucleic Acids via Liposome Signal Amplification in Mass Spectrometry

“…It has been reported that PEG polymers are hydrophilic and can reduce the adsorption of nucleic acids, proteins, and other substances on the nanoparticle surface [ 26 , 27 , 28 ]. The effect of DSPE-PEG2000-N3 on liposome dispersion was investigated by adding different proportions of DSPE-PEG2000-N3 as a liposome component.…”

Disassembly of Nanospheres with a PEG Shell upon Adsorption onto PEGylated Substrates

“…This disassembly is consistent with the flat surface layer seen in AFM (Figure ). It is possible that entanglements of the PEG segments on the corona of the nanosphere and the brushes of the PEG chain on the surface of these substrates produce a Velcro effect causing the nanosphere to unravel . This is the opposite of the repulsion of hydrophilic proteins from the near PEG-rich surfaces.…”

“…It is possible that entanglements of the PEG segments on the corona of the nanosphere and the brushes of the PEG chain on the surface of these substrates produce a Velcro effect causing the nanosphere to unravel. 41 This is the opposite of the repulsion of hydrophilic proteins from the near PEG-rich surfaces. Additionally, interactions between aromatic groups in the nanosphere core and the substrate polymer may result in deformation or disassembly of our nanospheres.…”

Modulation of Platelet-Surface Activation: Current State and Future Perspectives

“…The most prominent molecule that is used to create a hydrophilic surface is poly­(ethylene glycol) (PEG). By PEG coating, the surface becomes rendered polyhydrophilic resulting in reduced protein adsorption. ,, Additionally, the brush structure of the PEG molecules induces steric repulsion of proteins. − Chen et al confirmed that the modification of titanium with PEG improves the platelet’s acceptance and inhibits the activation of platelets . Although the PEGylation of surfaces is used routinely for many biomedical applications, some studies have shown that it cannot be generally referred to be a hemocompatible material.…”

“…By PEG coating, the surface becomes rendered polyhydrophilic resulting in reduced protein adsorption. 52,55,56 Additionally, the brush structure of the PEG molecules induces steric repulsion of proteins. 57−59 Chen et al confirmed that the modification of titanium with PEG improves the platelet's acceptance and inhibits the activation of platelets.…”