Complex Hydrogel Systems Composed of Polymers, Liposomes, and Cyclodextrins: Implications of Composition on Rheological Properties and Aging
Autor: | Sophia G. Antimisiaris, Christos A. Aggelopoulos, Christos D. Tsakiroglou, Pavlos G. Klepetsanis, Spyridon Mourtas |
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Rok vydání: | 2009 |
Předmět: |
Aging
Polymers Sonication Acrylic Resins Molecular Conformation chemistry.chemical_compound Differential scanning calorimetry Phosphatidylcholine Spectroscopy Fourier Transform Infrared Electrochemistry General Materials Science Cellulose Spectroscopy chemistry.chemical_classification Cyclodextrins Liposome Chromatography Calorimetry Differential Scanning Cyclodextrin Vesicle technology industry and agriculture Hydrogels Surfaces and Interfaces Polymer Condensed Matter Physics Models Chemical chemistry Chemical engineering Liposomes Self-healing hydrogels Phosphatidylcholines lipids (amino acids peptides and proteins) Stress Mechanical Rheology Gels Hydrogen |
Zdroj: | Langmuir. 25:8480-8488 |
ISSN: | 1520-5827 0743-7463 |
Popis: | Rheological properties of complex hydrogels containing different amounts of liposomes and/or cyclodextrin (CD) were evaluated. Sonicated unilamellar vesicles (SUV) were loaded in a hydrogel composed of Carbopol 974 NF and hydroxyethylcellulose (Natrosol 250 HX). Phosphatidylcholine (PC) and hydrogenated-PC (HPC) liposomes, both mixed with cholesterol in a 2:1 lipid/chol mol ratio, were used. In some cases, hydroxypropyl-beta-cyclodextrin was also added (100 or 400 mg/mL). Gels were incubated at 40 degrees C/75% humidity for 7 days or 1 month to evaluate the effect of aging on their rheological properties. FTIR and DSC studies were performed to investigate possible interactions between the polymers and CD molecules at different CD concentrations. Static and dynamic rheological measurements were carried out. All gels had shear-thinning behavior (fitted well by the Cross model) with the exception of gels containing high concentrations of CD that were transformed into nonflowing elastic sticky solids, especially after aging. The more pronounced elastic behavior of gels containing 400 mg/mL CD is reflected by the higher values of relaxation strengths over all relaxation times. Complete interaction between polymers and CD, in the high-CD-content gels, as proven by FTIR and DSC studies, explains the dominating contribution of CD on gel characteristics. The addition of liposomes to such CD-containing gels has a substantial effect on their rheological properties, which are dependent on the liposome type (HPC/chol liposomesPC/chol) and the lipid/CD ratio. This is explained by the "neutralization" of some CD molecules that prefer to interact with chol molecules that they extract from the lipid membranes. Gels with a high CD concentration (400 mg/mL) are almost insensitive to aging, whereas all other gels become slightly more elastic and less viscous as aging proceeds. |
Databáze: | OpenAIRE |
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