Comparative Stability Studies of Poly(2-methyl-2-oxazoline) and Poly(ethylene glycol) Brush Coatings

Abstract

Non-fouling surfaces that resist non-specific adsorption of proteins, bacteria, and higher organisms are of particular interest in diverse applications ranging from marine coatings to diagnostic devices and biomedical implants. Poly(ethylene glycol) (PEG) is the most frequently used polymer to impart surfaces with such non-fouling properties. Nevertheless, limitations in PEG stability have stimulated research on alternative polymers that are potentially more stable than PEG. Among them, we previously investigated poly(2-methyl-2-oxazoline) (PMOXA), a peptidomimetic polymer, and found that PMOXA shows excellent anti-fouling properties. Here, we compare the stability of films self-assembled from graft copolymers exposing a dense brush layer of PEG and PMOXA side chains, respectively, in physiological and oxidative media. Before media exposure both film types prevented the adsorption of full serum proteins to below the detection limit of optical waveguide in situ measurements. Before and after media exposure for up to 2 weeks, the total film thickness, chemical composition, and total adsorbed mass of the films were quantified using variable angle spectroscopic ellipsometry (VASE), X-ray photoelectron spectroscopy (XPS), and optical waveguide lightmode spectroscopy (OWLS), respectively. We found (i) that PMOXA graft copolymer films were significantly more stable than PEG graft copolymer films and kept their protein-repellent properties under all investigated conditions and (ii) that film degradation was due to side chain degradation rather than due to copolymer desorption.

Design Strategies for Functionalized Poly(2-oxazoline)s and Derived Materials

“…This graft copolymer was used to form surface platforms on Nb 2 O 5 [114] to investigate the adhesion mechanism of Escherichia coli and in particular the influence of fimbriae expression. Expressing type 1 fimbriae bacteria adhered due to van der Waals forces and hydrophobic interactions.…”

On the long term antibacterial features of silver-doped diamondlike carbon coatings deposited via a hybrid plasma process

“…27 Nonetheless, one can question if such surfaces are robust enough for the harsh hospital operating conditions, given the mechanical and chemical fragility of tethered polymer surface layers. [28][29][30][31] Alternatively, biocide-releasing coatings offer the advantage of embedding the bioactive element in a scaffold, which can be chosen, for example, for its mechanical and chemical stability. Therefore, the remaining challenge in this case is to control the release kinetics, which governs the duration and effectiveness of the antibacterial action.…”

The synthesis of polymeric dual-functional antimicrobial surface based on poly(2-methyl-2-oxazoline)

“…Thus, α = I -CH2-N(C=O)- , which results in α value of 0.33. We have previously found that this value is the optimum grafting density value for PLL-g-PMOXA brush as biopassive surface coating (Pidhatika et al, 2010, Pidhatika et al, 2012. Figure 5 shows the NMR spectrum of PLL-g-PMOXA-QAC and the assignment of peaks.…”

“…One of them is loss of biopassive function in case of long-term application. It is believed that PEG degrades by auto-oxidation due to the repetitive oxygen atom in its structure (Pidhatika et al, 2012, Chen et al, 2014.…”

“…Series of brush-like copolymers consisting of a polycationic poly(L-lysine) (PLL) backbone and PMOXA side chains (PLL-g-PMOXA) have been immobilized on Nb 2 O 5 -surface And proven to have very similar protein-repellent properties when compared to the extensively studied (PEG)-based system (PLL-g-PEG) (Pasche et al, 2003). In terms of stability, PMOXA that mimics polypeptide structure was found to be significantly more stable compared to PEG with polyether structure (Pidhatika et al, 2012). However, biopassive coating may deteriorate during longer-term contact with bacteria or body fl uid in general due to mechanical defects of the layer and secretion of oxidative substances from bacteria, requiring other strategies to explore.…”