Surface Preconditioning Influences the Antifouling Capabilities of Zwitterionic and Nonionic Polymer Brushes

Abstract

Polymer brushes not only represent emerging surface platforms for numerous bioanalytical and biological applications but also create advanced surface-tethered systems to mimic real-life biological processes. In particular, zwitterionic and nonionic polymer brushes have been intensively studied because of their extraordinary resistance to nonspecific adsorption of biomolecules (antifouling characteristics) as well as the ability to be functionalized with bioactive molecules. However, the relation between antifouling behavior in real-world biological media and structural changes of polymer brushes induced by surface preconditioning in different environments remains unexplored. In this work, we use multiple methods to study the structural properties of numerous brushes under variable ionic concentrations and determine the impact of these changes on resistance to fouling from undiluted blood plasma. We describe different mechanisms of swelling, depending on both the polymer brush coating properties and the environmental conditions that affect changes in both hydration levels and thickness. Using both fluorescent and surface plasmon resonance methods, we found that the antifouling behavior of these brushes is strongly dependent on the aforementioned structural changes. Moreover, preconditioning of the brush coatings (incubation at a variable salt concentration or drying) prior to biomolecule interaction may significantly improve the antifouling performance. These results suggest a new simple approach to improve the antifouling behavior of polymer brushes. In addition, the results herein enhance the understanding for improved design of antifouling and bioresponsive brushes employed in biosensor and biomimetic applications.

Functionalizable Antifouling Coatings as Tunable Platforms for the Stress-Driven Manipulation of Living Cell Machinery

“…Using the available methods (for more details, see also the Supplementary Materials), a direct determination was found to be quite challenging. For example, while the level of immobilized RGD peptides on OEG SAM was quantified by the SPR method, it was not possible to determine the RGD-peptide surface concentration on the pCB-based coatings due to a very high pCB-based zwitterionic surface hydrophilicity [33,39,53] combined with a relatively small molecular weight of the RGD peptide ( Figure S2 in the Supplementary Materials). Therefore, we were not able to directly compare the level of functionalization of pCBAA, pCBMAA-based coatings, and OEG-based coatings.…”

Biorecognition antifouling coatings in complex biological fluids: a review of functionalization aspects

“…It is worth mentioning that the choice of the characterization technique influences the portion of fouling properties that are observed, and thus potentially leads to different results obtained for the same sample. 191,192 This section provides a brief overview of the techniques and experimental conditions most frequently used for fouling measurements with an emphasis on their major limitations.…”

“…86,197 Moreover, the SPR technique may be prone to the interference of the refractive index changes caused by the bound mass with refractive index changes caused by swelling of highly hydratable structures. 192…”

“…It is worth noting that in ref. 192 the authors suggest that the resistance of polymer brushes can be influenced by surface preconditioning. For example, for higher salt concentration-preconditioning the resistance of pCBMAA was shown to be higher compared to pCBAA.…”

Controlling Experimental Parameters to Improve Characterization of Biomaterial Fouling

“…Furthermore, many techniques use sensors or surfaces that are coated with low-fouling materials; grafting efficiency will therefore further introduce variability. Additionally, it has recently been shown that minor deviations during sample preparation for characterization techniques can also impact fouling levels (Visova et al, 2020). To overcome these differences in sample preparation, as well as reduce variability between samples, several techniques for characterizing low-fouling coatings have been extended to high-throughput screening (HTS) (Hook et al, 2010(Hook et al, , 2012Magennis et al, 2016).…”