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Stetsyshyn Y.,Lvivska Polytechnika National University | Zemla J.,Jagiellonian University | Zolobko T.,Lvivska Polytechnika National University | Fornal K.,Jagiellonian University | And 9 more authors.
Journal of Colloid and Interface Science | Year: 2012

Poly(N-isopropylacrylamide) (PNIPAM) coatings attached to glass with novel approach involving polymerization from oligoperoxide grafted to surface with (3-aminopropyl)triethoxysilane exhibit not only temperature- but also pH-dependence of wettability and protein adsorption. Wettability and composition of coatings, fabricated with different polymerization times, were determined using contact angle measurements and Time Of Flight-Secondary Ion Mass Spectrometry (TOF-SIMS), respectively. Thermal response of wettability, measured between 20 and 40. °C, was prominent at pH 9 and 7 and diminished or absent at pH 5 and 3. This indicates a transition between hydrated loose coils and hydrophobic collapsed chains that is blocked at low pH. Higher surface roughness and dramatically increased adsorption of model protein (lentil lectin labeled with fluorescein isothiocyanate) were observed with AFM and fluorescence microscopy to occur in hydrophobic phases (at pH 3, for pH varied at constant temperature of 22. °C and at ∼33. °C, for temperature varied at constant pH 9). Protein adsorption response to pH was confirmed by TOF-SIMS and Principal Component Analysis. © 2012 Elsevier Inc. Source


Kostruba A.,Lviv Institute for Physical Optics | Kostruba A.,Lviv Academy of Commerce | Kulyk B.,Ivan Franko National University of Lviv | Turko B.,Ivan Franko National University of Lviv
Journal of Alloys and Compounds | Year: 2012

Copper-doped ZnO films with thickness about 1200 nm were prepared by radio-frequency (RF)-magnetron sputtering on glass substrates. The influence of dopant on the optical properties was investigated using ellipsometry technique. It has been found that only three layer model of surface can be satisfactory fitted with experimental data of ellipsometric measurements obtained in wide range of incident angles. Presence of additional layers within the model can be explained by the interface roughness. The atomic force microscopy (AFM) analysis indicates that thickness of additional layers and value of interface roughness are commensurable. The optical parameters of copper-doped ZnO structures with different concentration of copper dopant were obtained using the fitting procedure within the three-layer model. Absence of copper clusters in the ZnO:Cu layer microstructure was confirmed using X-ray diffraction and the effective media approximation (EMA) analysis. Refractive indices of doped ZnO:Cu layers (n = 2.002...2.04) are very close to the index of ZnO film (n = 1.98) at 632.8 nm. Extinction coefficient increase gradually to (k = 0.002) with the dopant concentration increasing. © 2012 Elsevier B.V. Source


Stetsyshyn Y.,Lvivska Polytechnika National University | Raczkowska J.,Jagiellonian University | Budkowski A.,Jagiellonian University | Kostruba A.,Lviv Academy of Commerce | And 7 more authors.
Langmuir | Year: 2015

Properties of novel temperature-responsive hydroxyl-containing poly(pentaerythritol monomethacrylate) (PPM) coatings, polymerized from oligoperoxide grafted to glass surface premodified with (3-aminopropyl)triethoxysilane, are presented. Molecular composition, chemical state, thickness, and wettability are examined with time of flight-secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), ellipsometry, and contact angle measurements, respectively. Temperature-induced changes in hydrophobicity of grafted PPM brushes are revealed by water contact angle and ellipsometric measurements. Partial postpolymerization modification of hydroxyl groups (maximum a few percent), performed with acetyl chloride or pyromellitic acid chloride, is demonstrated to preserve thermal response of coatings. Adsorption of bovine serum albumin to PPM brushes, observed with fluorescence microscopy, is higher than on glass in contrast to similar hydroxyl-containing layers reported as nonfouling. Enhanced and temperature-controlled protein adsorption is obtained after postpolymerization modification with pyromellitic acid chloride. © 2015 American Chemical Society. Source

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