Impact of the various buffer solutions on the temperature‑responsive properties of POEGMA‑grafted brush coatings

The effect of temperature and buffer solutions with different pH (often used in biomedical applications) on the behavior of POEGMA brush coatings, synthesized without incorporated functional groups, was for the first time studied in details using water contact angle (CA) measurements and atomic force microscopy (AFM). Thermal response of grafted brush-coatings based on poly(oligo(ethylene glycol) methacrylate)s (POEGMA)s is driven by lower critical solution temperature (LCST) phenomenon. Obtained CA and AFM results suggest strong impact of the buffer solutions on the values of LCST transition and contact angle ranges, as well as on coatings morphology. In turn, ellipsometry data reflect penetration of salt ions from buffer solutions into brush-coatings. In contrast to “typical” behavior of POEGMA coatings in water, different mechanisms available below LCST in the buffer solutions destroy hydrated layers surrounding POEGMA macromolecules leading to their collapse

Temperature-controlled three-stage switching of wetting, morphology and protein adsorption

The novel polymeric coatings of oligoperoxide-graft-poly(4-vinylpyridine-co-oligo(ethylene glycol)ethyl ether methacrylate246) [oligoperoxide-graft-P(4VP-co-OEGMA246)] attached to glass were successfully fabricated. The composition, thickness, morphology, and wettability of resulting coatings were analyzed using X-ray photoelectron spectroscopy, ellipsometry, atomic force microscopy, and contact angle measurements, respectively. In addition, adsorption of the bovine serum albumin was examined with fluorescence microscopy. The thermal response of wettability and morphology of the coatings followed by that of protein adsorption revealed two distinct transitions at 10 and 23 °C. For the first time, three stage switching was observed not only for surface wetting but also for morphology and protein adsorption. Moreover, the influence of the pH on thermo-sensitivity of modified surfaces was shown

Cholesterol-based grafted polymer brushes as alignment coating with temperature-tuned anchoring for nematic liquid crystals

Novel alignment coating with temperature-tuned anchoring for nematic liquid crystals (NLCs) was successfully fabricated in three step process, involving polymerization of poly(cholesteryl methacrylate) (PChMa) from oligoproxide grafted to the glass surface premodified with 3-aminopropyltriethoxysilane. Molecular composition, thickness, wettability of the PChMa coating and its alignment action for a NLC were examined with time of flight-secondary ion mass spectrometry, ellipsometry, contact angle measurements, polarization optical microscopy and commercially produced PolScope technique allowing for mapping of the optic axis and optical retardance within the microscope field view. We find that the PChMa coating provides a specific monotonous increase (decrease) in the tilt angle of the NLC director with respect to the substrates normal upon heating (cooling) referred to as anchoring tuning

Temperature-controlled orientation of proteins on temperature-responsive grafted polymer brushes : poly(butyl methacrylate) vs poly(butyl acrylate) : morphology, wetting, and protein adsorption

Poly(n-butyl methacrylate) (PBMA) or poly(n-butyl acrylate) (PBA)-grafted brush coatings attached to glass were successfully prepared using atom-transfer radical polymerization "from the surface". The thicknesses and composition of the PBMA and PBA coatings were examined using ellipsometry and time-of-flight secondary ion mass spectrometry (ToF-SIMS), respectively. For PBMA, the glass-transition temperature constitutes a range close to the physiological limit, which is in contrast to PBA, where the glass-transition temperature is around −55 °C. Atomic force microscopy studies at different temperatures suggest a strong morphological transformation for PBMA coatings, in contrast to PBA, where such essential changes in the surface morphology are absent. Besides, for PBMA coatings, protein adsorption depicts a strong temperature dependence. The combination of bovine serum albumin and anti-IgG structure analysis with the principal component analysis of ToF-SIMS spectra revealed a different orientation of proteins adsorbed to PBMA coatings at different temperatures. In addition, the biological activity of anti-IgG molecules adsorbed at different temperatures was evaluated through tracing the specific binding with goat IgG

Synthesis and postpolymerization modification of thermoresponsive coatings based on pentaerythritol monomethacrylate : surface analysis, wettability, and protein adsorption

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

Temperature-responsive properties of poly(4-vinylpyridine) coatings : influence of temperature on the wettability, morphology, and protein adsorption

Although the pH-response of poly(vinylpyridine)-based systems is well-known and indeed used in several biomedical applications, the impact of temperature on the properties of this polymer has not been investigated in detail so far. Herein, we demonstrate the temperature-responsiveness and switchable wettability of two poly(4-vinylpyridine) coatings, mimicking the behavior of materials with lower critical solution temperature. The thermal response of P4VP spin-coated films, solvent cast on a glass, is weaker than that observed for P4VP-grafted brushes, fabricated via polymerization from an oligoperoxide grafted on an amino-silanized glass. Both the P4VP coatings exhibit a temperature dependence of the water contact angle with a well-defined transition at 13–14 °C. This transition is absent at acid pH levels wherein almost all pyridyl groups are protonated. The P4VP-grafted brushes were used to examine the impact of temperature on the surface morphology and protein adsorption. The coating surface, recorded with atomic force microscopy, evolved noticeably at alkaline pH, from being relatively smooth at 10 °C to structured and rough at 20 °C. In turn, at acid pH levels, flat surfaces with rare elevations were observed at both temperatures. The adsorption of bovine serum albumin and human fibrinogen was observed with fluorescence microscopy to be significantly more efficient for temperatures above the transition, indicating that P4VP coatings can act as a noteworthy switching material