Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: POSTER: Biological Systems + New Materials

CPP 20.15: Poster

Wednesday, March 28, 2007, 16:00–18:30, Poster B

Optimization of Alginate-Based Isocapillary Matrices for their Application in Biomedicine — •Matthias Kellermeier, Rainer Müller, and Werner Kunz — Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg

Unidirectional diffusion of divalent cations such as Cu²⁺ or Ca²⁺ into sols of sodium alginate provokes the formation of a hydrogel pervaded by capillaries which are aligned parallel to the direction of the cation flow showing hexagonal arrangement in cross-section. Gelation occurs due to the complexation and dehydration of the polysaccharide chains by the cations, leading to the release of water into the free lumen of the forming capillaries and the fixation of the polymer in the walls around them. Typical pore diameters vary in the range of 5-100 µm. The formation of highly ordered capillaries in alginate gels can be interpreted as a dissipative process similar to Rayleigh-Bénard convection, resulting from opposing diffusion gradients and friction. With respect to biomedical applications, these isocapillary gels can be modified either by incorporating inorganic particles into the gel matrix followed by densification and ceramization, or by stabilization of the alginate framework via covalent cross-linking of the chains, resulting in scaffolds useable as bone implants and for the regeneration of nerves. The aim of the present study is to optimize the pore structure of alginate gels in view of these applications. We focus on the effect of a series of additives in the sol, such as salts, sugars and surfactants. Furthermore, we have studied the variability of the pore structure of alginate gels by employing both different cations and counter-ions.