Graft coupling of PEO to mixed cellulose esters microfiltration membranes by UV irradiation

Journal of Colloid and Interface Science

McGuire

2011

Stable, pendant polyethylene oxide (PEO) layers were formed on medical-grade Pellethane® and Tygon® polyurethane surfaces, by adsorption and gamma-irradiation of PEO-polybutadiene-PEO triblock surfactants. Coated and uncoated polyurethanes were challenged individually or sequentially with nisin (a small polypeptide with antimicrobial activity) and/or fibrinogen, and then analyzed with time-of-flight secondary ion mass spectrometry (TOF-SIMS). Data reduction by robust principal components analysis (PCA) allowed detection of outliers, and distinguished adsorbed nisin and fibrinogen. Fibrinogen-contacted surfaces, with or without nisin, were very similar on uncoated polymer surfaces, consistent with nearly complete displacement or coverage of previously-adsorbed nisin by fibrinogen. In contrast, nisin-loaded PEO layers remained essentially unchanged upon challenge with fibrinogen, suggesting that the adsorbed nisin is stabilized within the pendant PEO layer, while the peptide-loaded PEO layer retains its ability to repel large proteins. Coatings of PEO loaded with therapeutic polypeptides on medical polymers have the potential to be used to produce anti-fouling and biofunctional surfaces for implantable or blood-contacting devices.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Detection of nisin and fibrinogen adsorption on poly(ethylene oxide) coated polyurethane surfaces by time-of-flight secondary ion mass spectrometry (TOF-SIMS)

Journal of Colloid and Interface Science

McGuire

2011

“…In the present study, triblock immobilization on layers formed by the monofunctional silane ADCS was also evaluated; this reagent cannot polymerize, and thus was expected to produce a smoother, more uniform layer for triblock coating than TCVS [19]. Representative zeta potential measurements of uncoated and F108-coated TCVS/ADCS-treated microsphere suspensions which were not γ-irradiated are shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

Nisin adsorption to polyethylene oxide layers and its resistance to elution in the presence of fibrinogen

Ryder

Journal of Colloid and Interface Science

Auxier

et al. 2010

The adsorption and elution of the antimicrobial peptide nisin at silanized silica surfaces coated to present pendant polyethylene oxide chains was detected in situ by zeta potential measurements. Silica microspheres were treated with trichlorovinylsilane to introduce hydrophobic vinyl groups, followed by self assembly of the polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) triblock surfactant Pluronic ® F108, or an F108 derivative with nitrilotriacetic acid endgroups. Triblock-coated microspheres were γ-irradiated to covalently stabilize the PPOsurface association. PEO layer stability was evaluated by triblock resistance to elution by SDS, and layer uniformity was evaluated by fibrinogen repulsion. Introduction of nisin to uncoated or triblock-coated microspheres produced a significant positive change in surface charge (zeta potential) as a result of adsorption of the cationic peptide. In sequential adsorption experiments, the introduction of fibrinogen to nisin-loaded triblock layers caused a decrease in zeta potential that was consistent with partial elution of nisin and/or preferential location of fibrinogen at the interface. This change was substantially more pronounced for uncoated than triblock-coated silica, indicating that the PEO layer offers enhanced resistance to nisin elution.

“…Furthermore, plasma has been used to modify hydrophobic surfaces for improved cell adhesion and so was not deemed an appropriate cleaning method. UV/Ozone was used in initial tests but was ultimately excluded because surfaces did not appear to be improved by the process (data not shown), and UV radiation has been used to graft polymers to hydrophobic surfaces through UV‐induced surface modification, so as with plasma treatment, which was deemed inappropriate for cleaning.…”

Section: Resultsmentioning

confidence: 99%

Cleaning requirements for silica‐coated sensors used in optical waveguide lightmode spectroscopy

Ryder

McGuire

Surface & Interface Analysis

2013

Optical waveguide lightmode spectroscopy (OWLS), based on the incoupling of laser light into a waveguide sensor by an optical grating, allows for the in situ measurement of protein adsorption. Few reports have described cleaning methods for the surfaces of such sensors, and in this investigation, we compare common methods for cleaning of silica surfaces in relation to their effectiveness for cleaning silica‐coated waveguide sensors used in OWLS. For this purpose, atomic force microscopy (AFM) analysis of surface morphology and OWLS detection of protein adsorption kinetics were used to evaluate waveguide sensors before and after cleaning. While AFM line scans showed a substantial increase in average waveguide peak‐to‐valley height after RCA cleaning relative to all other methods tested, chemical etching owing to the alkaline component of the rolling circle amplification method rendered the waveguide unusable for detection of protein adsorption with OWLS. A revised method, based on replacement of the alkaline step with immersion in sodium dodecyl sulfate, was not only effective at cleaning OWLS waveguides off‐the‐shelf but also showed excellent protein adsorption reproducibility after ex situ cleaning. Moreover, the revised method showed excellent reproducibility when applied in situ, between repeated adsorption‐elution cycles. Copyright © 2013 John Wiley & Sons, Ltd.