The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Calum J Drummond - One of the best experts on this subject based on the ideXlab platform.
-
effect of cosolvents on the self assembly of a non ionic Polyethylene Oxide polypropylene Oxide Polyethylene Oxide block copolymer in the protic ionic liquid ethylammonium nitrate
Journal of Colloid and Interface Science, 2015Co-Authors: Zhengfei Chen, Tamar L Greaves, Rachel A Caruso, Calum J DrummondAbstract:Abstract The effect of water and methanol on the self-assembled structures formed by the Polyethylene Oxide–polypropylene Oxide–Polyethylene Oxide block copolymer Pluronic P123 in ethylammonium nitrate was investigated by small angle X-ray scattering (SAXS). Two ternary phase diagrams were established. The addition of water had only a minor effect on the liquid crystal structures, however methanol had a significant effect, which was attributed to methanol being a good solvent for both the PEO and PPO blocks of the polymer. No lyotropic liquid crystal phases were retained when methanol reached 25 wt%. The phase behaviour did not change significantly over the temperature range from 25 to 45 °C.
-
Steric stabilisation of self-assembled cubic lyotropic liquid crystalline nanoparticles: high throughput evaluation of triblock Polyethylene Oxide-polypropylene Oxide-Polyethylene Oxide copolymers
Soft Matter, 2011Co-Authors: Josephine Chong, Xavier Mulet, Lynne J. Waddington, Ben J. Boyd, Calum J DrummondAbstract:Nanostructured cubic lyotropic liquid crystalline colloidal particles (Cubosomes™) are of interest for applications such as drug and biomedical imaging agent encapsulation systems. Maintaining the stability and integrity of these nanoparticles over time is essential for their storage and application. It is well known that the triblock Polyethylene Oxide-polypropylene Oxide-Polyethylene Oxide (PEO-PPO-PEO) copolymer, Pluronic F127, imparts a steric barrier to aggregation of non-lamellar lyotropic liquid crystalline particles. However, few other stabilisers have been reported for these systems. Using high throughput methodologies to prepare and characterise dispersions of monoolein and phytantriol, the performance of a wide range of triblock PEO-PPO-PEO copolymers (Pluronics) was evaluated for optimal stabilisation of cubosomes. It is shown that Pluronic F108 is superior to Pluronic F127 as a stabiliser of monoolein based nanostructured particles, as it preserves the integrity of the double diamond inverse bicontinuous cubic phase internal structure of the particles, whilst maintaining colloidal stability.
Hian Kee Lee - One of the best experts on this subject based on the ideXlab platform.
-
Prevention of protein adsorption on surfaces by Polyethylene Oxide-polypropylene Oxide-Polyethylene Oxide triblock copolymers in capillary electrophoresis
Journal of Chromatography A, 1994Co-Authors: Hian Kee LeeAbstract:Protein adsorption to untreated fused-silica capillaries in capillary electrophoresis was prevented by a chemical modification of the capillary surface. This was achieved through the coating of Pluronic polymers onto capillaries which were pre-derivatised with silylating agents. The polymers were made up of Polyethylene Oxide-polypropylene Oxide-Polyethylene Oxide triblock copolymers. The coatings prevent protein adsorption and provide high-efficiency separations. Two different types of silylating agents were used and the effects of the concentrations on the stability and efficiency of the columns were examined. The application of these columns for capillary electrophoretic separation of protein samples was demonstrated.
Jennifer A. Neff - One of the best experts on this subject based on the ideXlab platform.
-
Nisin adsorption to Polyethylene Oxide layers and its resistance to elution in the presence of fibrinogen
Journal of colloid and interface science, 2010Co-Authors: Matthew P. Ryder, Karl F. Schilke, Julie A. Auxier, Joseph Mcguire, Jennifer A. NeffAbstract:Abstract 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 end groups. Triblock-coated microspheres were γ-irradiated to covalently stabilize the PPO-surface 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.
Gunnar A. Niklasson - One of the best experts on this subject based on the ideXlab platform.
-
Proton diffusion in Polyethylene Oxide : Relevance to electrochromic device design
Solar Energy Materials and Solar Cells, 2008Co-Authors: Gunnar A. NiklassonAbstract:Polyethylene Oxide is a frequently used component in polymer electrolytes developed for applications in electrochromic devices. The transmittance variation may occur as a result of either proton or lithium ion intercalation into the electrochromic films. Impedance spectroscopy data in the low-frequency space-charge relaxation regime can be used to obtain estimates of ion concentrations and ion diffusion coefficients in ion-conducting materials. We apply this method to literature data for pure Polyethylene Oxide where the residual conductivity is believed to be due to protons. The obtained diffusion coefficient is found to be in the order of, or higher than, reported lithium ion diffusion coefficients in low molecular weight Polyethylene Oxide. Hence it is likely that proton intercalation will be of importance for electrochromic devices, provided there is a significant amount of protons present.
Jeffrey A. Hubbell - One of the best experts on this subject based on the ideXlab platform.
-
Tissue response to intraperitoneal implants of Polyethylene Oxide-modified Polyethylene terephthalate.
Biomaterials, 2003Co-Authors: Neil P. Desai, Jeffrey A. HubbellAbstract:Polyethylene terephthalate films surface modified with Polyethylene Oxide of mol wt 18,500 g/mol (18.5 k) by a previously described technique, were implanted in the peritoneal cavity of mice, along with their respective untreated controls, for periods of 1-28 d. The implants were retrieved and examined for tissue reactivity and cellular adherence. The control Polyethylene terephthalate surfaces showed an initial inflammatory reaction followed by an extensive fibrotic response with a mean thickness of 60 microns at 28 d. By contrast, Polyethylene Oxide-modified Polyethylene terephthalate showed only a mild inflammatory response and no fibrotic encapsulation throughout the implantation period: at 28 d a cellular monolayer was observed. Apparently either the Polyethylene Oxide-modified surface was stimulating less inflammation, which was in turn stimulating less fibroblastic overgrowth, or the cellular adhesion to the Polyethylene Oxide-modified surface was too weak to support cellular multilayers. [on SciFinder (R)]
-
Surface-immobilized Polyethylene Oxide for bacterial repellence
Biomaterials, 1992Co-Authors: Neil P. Desai, Hossainy Syed F A, Jeffrey A. HubbellAbstract:Polyethylene terephthalate films were surface-modified with Polyethylene Oxide (18,500 g/mol) using a solution technique described previously. These films were investigated for their resistance to bacterial adhesion. Three bacterial strains most commonly associated with implant infections, Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa, were cultured in tryptic soya broth, human plasma and human serum on the polymeric substrates. Significant reductions (between 70 and 95%) in adherent bacteria were observed on the Polyethylene Oxide-modified substrates compared to the untreated control Polyethylene terephthalate. Surface modification with Polyethylene Oxide may reduce the risk of implant-associated infections. Plasma fibrinogen was observed to play an important role in the adhesion of all three of these species on both the Polyethylene Oxide-modified and control Polyethylene terephthalate materials. [on SciFinder (R)]
