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- Kessler, Vadim, et al.
(author)
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CaptiGel Technology for Encapsulation of Biomaterials and Medicines
- 2009
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Conference paper (other academic/artistic)abstract
- Inorganic materials receive increasing interest as components and major constituents of encapsulation formulations for bio-molecules and microorganisms. Sol-gel technology is broadly recognized as a versatile synthetic approach to colloidal inorganic materials, perspective as potential hydrosol and hydrogel matrices for encapsulation. The industrial development in this field has been mostly focused on silica in the view of the availability of both organic and inorganic precursors of silica gels and, especially, due to their easy handling and facile control over gelation parameters. Metal oxides have been practically excluded from this application domain, because of the high chemical reactivity and apparent bio-incompatibility of the related precursor chemicals. However, the metal oxides with compositions corresponding to naturally abundant biocompatible minerals, for example titanium dioxide (registered even as the Food Additive E171), can represent an attractive alternative to silica. Stable and biocompatible hydrosols and hydrogels of titanium dioxide and other metal oxides can be successfully prepared using modification of the related metal organic precursors with hydrophilic ligands, especially if the latter can be supplied with electric charge through interaction with acids or bases [1]. The produced colloids are then naturally buffered within biocompatible pH region. An attractive feature of the thus produced colloid particles is that they possess a core-shell structure: the crystalline core contributes with attractive UV-protective properties, while the amorphous shell hinders the negative photochemical activity and permits easy aggregation of the particles into continuous films, self-assembling at any phase boundary, for example, a cell membrane of a microorganism. This permits to produce formulations able to protect the encapsulated biomaterial from both chemical and physical hazards. Another attractive feature of titanium dioxide is its specific biodegradability, offering possibility of enhanced chemically and bio-chemically triggered release [2]. Metal oxide surfaces possess even a pronounced affinity to carboxylate and phosphate/phosphonate functions present in the formula of many important medicines. Release of these drugs after their chemosorption in the oxide hydrogels is a slow and kinetically controlled process sought in many medical applications, which makes the produced materials attractive for drug delivery applications. 1. Kessler, V.G.; Seisenbaeva, G.A.; Håkansson, S.; Unell, M, Metal Oxide Hydrogels and Hydrosols, Their Preparation and Use, PCT application WO07145573. 2. Kessler, V.G.; Seisenbaeva, G.A.; Håkansson, S.; Unell, M, Chemically Triggered Biodelivery Using Metal–Organic Sol–Gel Synthesis. Angew. Chem. Int. Ed., 2008. 47(44): p. 8506-8509
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