Structural Characterization of Microemulsion-based Cellulose Gels used as Carriers of Biocompatible Ingredients
Microemulsion-based gels of cellulose, the most abundant renewable biopolymer in nature, have already been applied as carriers of biocompatible ingredients. In this study we discuss the combined analytical approach, using small-angle X-ray scattering, electron microscopy and other methods for elucidating the structure and properties of this gel system which offers high potential for use in biocompatible encapsulations.
Gels are three-dimensional macromolecular networks that are swollen by large amounts of a solvent. They find wide use in various applications such as food, drug delivery and catalysis.
Gels based on biopolymers e.g., polysaccharides such as cellulose or starch attracted significant at-tention because they originate from renewable re-sources, can be efficiently produced and are biode-gradable. In particular, cellulose derivatives such as hydroxypropyl-methylcellulose (HPMC) are interest-ing materials exhibiting unique physicochemical properties. HPMC is a water-swelling biopolymer which can be combined with a microemulsion to form a microemulsion-based organogel (MBGs).1
In this study, MBG systems based on HPMC and a microemulsion formed with a bis-(2-ethylhexyl) sul-fosuccinate sodium salt (AOT) in isooctane micro-emulsion were investigated. The enzyme lipase was used as a model-encapsulated molecule. Different methods, including small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and electron paramagnetic resonance (EPR) were applied to examine the morphology of the HPMC system. SAXS measurements in particular, performed with the Anton Paar SAXSpoint 5.0 laboratory SAXS/WAXS system provided valuable findings on the investigated microemulsions and the finally obtained MBG sys-tem:
- structure and size of the AOT microemulsions,
- presence of microemulsions after incorporation of the microemulsion into the HPMC matrix, and
- a higher stiffness of the final HPMC gel is reached in dependence of the AOT concentration of the microemulsion.
- Xenakis, A et al., Progr. Colloid Polym. Sci. 2000, 115, 192-195
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