Alginate-based composites - carriers of bioactive materials Preliminary study
Ewa Stodolak, Marta Błażewicz Akademia Górniczo-Hutnicza, Wydział Inżynierii Materiałowej i Ceramiki, Katedra Biomateriałów, al. Mickiewicza 30, 30-059 Kraków, Poland
Quarterly No. 4, 2008 pages 375-378
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abstract For many years alginates have been used in biomedical engineering. This study is devoted to biopolymeric composite materials based on alginate salts. Three kinds of composite materials were produced and characterised. Dispersed phase consisted of ceramic materials such as: nano-hydroxyapatite (nHAp), nano-silica (nSiO2) or bioglass (BG). The composite matrix was sodium alginate solution consolidated in inorganic salt solution (CaCl¬2). In effect of chemical reactions, ion exchange followed by gelling, composite materials Ca(Alg)2/nHAp, Ca(Alg)2/nSiO2, Ca(Alg)2/BG were obtained. The alginate spheres were made from the bio-polymer powder (NovaMatrix-Biopolymer, Norway) containing 6065% of G monomer. The formation of the spheres was realised by dropping in the sodium alginate solution into a gelling bath with 3% CaCl2 solution. The biopolymer matrix (NaAlg) was modified with: 3% wt. nanohydroxyapatite (AGH-UST, Department of Advanced Ceramics), 3% wt. colloidal silica (nSiO2), 3% wt. bioglass (AGH-UST, Department of Glass and Amorphous Coatings Technology). Spheres without modifying agent were used as the reference material. Surface of the composite spheres and their shrinkage was investigated using stereoscope microscope. Microstructural features of composites beads were observed under scanning electron microscope. Dispersion of ceramic particles in the biopolimer matrix were investigated. All samples Ca(Alg)2/nHAp, Ca(Alg)2/n-SiO2, Ca(Alg)2/BG were tested in vitro condition (incubated in water, at 37C/30 days). Curves of changing pH immersion medium were the same in all types of samples. Result of investigation shown that degradation time of the investigated composite materials is different, and depends on a presence of Na¬¬¬¬¬¬+, K+, and Cl ions. Their durability decreases in the following order of immersing medium: PBS→Ringer solution→water. Dispersion of the modyfing particles depends on their chemical characteristics and size. The best dispersion was achieved in case of n-HAp particles, and the worst in case of BG. The alginate spheres may be an effective carrier of bioactive substances, such as nHAp, n-SiO2, BG, which are released during their degradation and can increase reconstruction and regeneration rates of the damaged tissue. Keywords: alginate, bioactive delivery system, multifunctional composites