Article Cite This: Langmuir XXXX, XXX, XXX−XXX
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Evaluating the Effect of Shear Stress on Graft-To Zwitterionic Polycarboxybetaine Coating Stability Using a Flow Cell Andrew Belanger,† Andre Decarmine,‡ Shaoyi Jiang,∥ Keith Cook,⊥ and Kagya A. Amoako*,†,§ Department of Mechanical, ‡Chemical, and §Biomedical Engineering, University of New Haven, West Haven, Connecticut 06516, United States ∥ Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States ⊥ Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States Downloaded via UNIV OF SUNDERLAND on October 12, 2018 at 06:14:45 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.
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ABSTRACT: The effect of surface coatings on the performance of antifouling activity under flow can be influenced by the flow/coating interactions. This study evaluates the effect of surface coatings on antifouling activity under different flows for the analyses of coating stability. This was done by exposing DOPA-PCB-300/dopamine coated polydimethylsiloxane (PDMS) to physiological shear stresses using a recirculation system which consisted of dual chamber acrylic flow cells, tygon tubing, flow probe and meter, and perfusion pumps. The effect of shear stress induced by phosphate buffered saline flow on coating stability was characterized with differences in fibrinogen adsorption between control (coated PDMS not loaded with shear stress) and coated samples loaded with various shear stresses. Fibrinogen adsorption data showed that relative adsorption on coated PDMS that were not exposed to shear (5.73% ± 1.97%) was significantly lower than uncoated PDMS (100%, p < 0.001). Furthermore, this fouling level, although lower, was not significantly different from coated PDMS membranes that were exposed to 1 dyn/cm2 (9.55% ± 0.09%, p = 0.23), 6 dyn/cm2 (15.92% ± 10.88%, p = 0.14), and 10 dyn/cm2 (21.62% ± 13.68%, p = 0.08). Our results show that DOPA-PCB-300/ dopamine coatings are stable, with minimal erosion, under shear stresses tested. The techniques from this fundamental study may be used to determine the limits of stability of coatings in long-term experiments.
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“graft-to”1 with the former requiring initiator immobilization to the surface using adhesive linkers followed by polymerization by atomic transfer radical polymerization initiated by the immobilized initiators.17−20 On the other hand, the “‘graft-to’” method used in this study requires direct attachment of preprepared polymers containing nonfouling zwitterionic and adhesive groups, such as 3,4-dihydroxyphenylalanine (DOPA) groups.21−23 Polybetaines such as polysolfubetaine and polycarboxybetaine have been grafted to or from gold surfaces using thiols as adhesive linkers3,4,7,24−27 on glass with silane linkers,28 and on many hydrophobic surfaces with hydrophobic moieties linkers29−31 or DOPA linkers.13,14 DOPA or catechol derivatives have been successfully used for the functional modification of surfaces21,22,32−42 and have proven to be a versatile technique for the efficient, convenient, and effective anchoring of zwitterionic polymers onto surfaces.1,43 However, while some surfaces coated with pCB can show undetectable nonspecific protein adsorption (
