Crosslinking Polymer Brushes with Ethylene Glycol-Containing Segments: Influence on Physicochemical and Antifouling Properties

Abstract

The introduction of different types and concentrations of crosslinks within poly(hydroxyethyl methacrylate) (PHEMA) brushes influences their interfacial, physicochemical properties, ultimately governing their adsorption of proteins. PHEMA brushes and brush-hydrogels were synthesized by surface-initiated, atom-transfer radical polymerization (SI-ATRP) from HEMA, with and without the addition of di(ethylene glycol) dimethacrylate (DEGDMA) or tetra(ethylene glycol) dimethacrylate (TEGDMA) as crosslinkers. Linear (pure PHEMA) brushes show high hydration and low modulus and additionally provide an efficient barrier against nonspecific protein adsorption. In contrast, brush-hydrogels are stiffer and less hydrated, and the presence of crosslinks affects the entropy-driven, conformational barrier that hinders the surface interaction of biomolecules with brushes. This leads to the physisorption of proteins at low concentrations of short crosslinks. At higher contents of DEGDMA or in the presence of longer TEGDMA-based crosslinks, brush-hydrogels recover their antifouling properties due to the increase in interfacial water association by the higher concentration of ethylene glycol (EG) units.

Monophosphonic versus Multiphosphonic Acid Based PEGylated Polymers for Functionalization and Stabilization of Metal (Ce, Fe, Ti, Al) Oxide Nanoparticles in Biological Media

“…It is found that the particles coated with monofunctionalized polymers exhibit a mitigated stability over time (<1 week), whereas the multifunctionalized copolymers provide resilient coatings and long-term stability (> months). [14,15,17,[20][21][22][23][24][25][26][27][28][29][30] Within a few exceptions, [20,[31][32][33][34][35] functional polymers are generally synthesized for a single type of particles and for a predetermined application. The study suggests that the proposed coating allows controlling nanomaterial interfacial properties in biological environments.…”

Loops and Cycles at Surfaces: The Unique Properties of Topological Polymer Brushes

“…Alternatively, the interfacial physicochemical properties of polymer brushes can be conveniently varied by applying different polymer architectures or topologies, beyond linearity, often keeping constant the overall polymer composition. By this approach, the introduction of crosslinks, side chains or branchings along the grafted polymers enabled the precise tuning of brush swelling, its nanomechanical and nanotribological characteristics, while increasing the surface concentration of functional groups available for post‐modification …”

Using Polymers to Impart Lubricity and Biopassivity to Surfaces: Are These Properties Linked?

“…[70 -72] As an example, the conformational restrictions that occur upon crosslinking densely grafted poly(hydrox-yethyl methacrylate) (PHEMA) brushes with oligo (ethylene glycol) dimethacrylates (OEGDMA) during surface-initiated atom transfer radical polymerization (SI-ATRP), [73] lead to an increase in the amount of protein fouling that occurs upon exposure to serum. [74] Surprisingly, though, when the concentration or molecular weight of EG-based crosslinks was increased, the non-specific adsorption of proteins was actually reduced. In other words, it appears that simply the presence of EG in the structure leads to a reduction in protein adsorption, even when the conformational entropy of the brush is reduced by crosslinking.…”

“…Not only the chemical composition but also the architecture of polymer brushes and brush-hydrogels consisting of PHEMA are responsible for determining their tribological and protein-repellent properties. Crosslinking was achieved by means of OEG dimethacrylates (Reprinted with kind permission from Ref [74],. Copyright 2016 American Chemical Society).…”

“…a) Dry thickness of adsorbed proteins on brushes and brush-hydrogels consisting of PHEMA, measured by VASE, and b) the hydrated protein uptake for the same coatings measured by QCMÀ D after 90 minutes of exposure to full serum (FS) (violet bars) and FS + fibrinogen (grey bars). (Reprinted with kind permission from Ref [74],. Copyright 2016 American Chemical Society).…”