Kapillarstrukturen in ionotropen Gelen

Novel Biomaterials with Parallel Aligned Pore Channels by Directed Ionotropic Gelation of Alginate: Mimicking the Anisotropic Structure of Bone Tissue

“…Sketch of the process of ionotropic gelation of alginate. The scheme in the middle was adapted from Wenger (1998) pushed by the gelation front towards the sol creating electrolyte containing and alginate free pore channels (Thiele & Hallich, 1957;Thiele, 1967b). Khairou and co-workers described the sol-gel-formation as diffusion controlled process which one step of primary membran formation and further growth of the anisotropic gel (Khairou et al, 2002).…”

“…So far about growth but what about the initiation of the pores? Thiele and Hallich postulated periodic water droplets which segregate by the dehydration during gelation (Thiele & Hallich, 1957). The contraction of the alginate causes accumulations and lower concentrated areas as nucleation seeds (Purz, 1972).…”

“…Adjusting the pH value, mostly HCl or NaOH is used which also changes the ion strength and therefore the electrostatic conditions within the sol. To achieve a homogenous alginate sol, the aqueous solution should be buffered because at low pH isotropic gelation can occur due to the ability of H + ions to interact with the alginate molecules (Thiele & Hallich, 1957). Fig.…”

“…Within the non-toxic elements, Zn 2+ generates hydrogels with pores larger than those derived from Ca 2+ (Thiele, 1967b). The more the cations orient the alginates molecules, the smaller the pore diameter of the gelled structure which also leads to an increase of the mechanical strength (Thiele & Hallich, 1957). But this does not primarily apply for the ceramics because the fibrous organic part was burnt.…”

Kinetics and Mechanism of Non-Isothermal Decomposition of Ca(II)-, Sr(II)- and Ba (II)- Cross-Linked Divalent Metal-Alginate Complexes

“…It is well-known that alginate as anionic polyelectrolyte has a high affinity for chelation with polyvalent metal ions in particularly with cations of alkaline-earth metal forming the corresponding cross-linked metal alginate complexes (Haugh & Smidsrod, 1965;Smidsrod, 1965;Haugh, Larsen, & Smidsrd, 1974;Schewiger,1964;Thiele & Anderson, 1955;Thiele & Hallich, 1957) through an egg-carton like-structures (Morris, Rees, & Thomas, 1978;Rees, 1972). Although, these polymeric metal alginate biomaterials are of great importance and has wide application in industrial technology such as in biomedical sensors, drug delivery, tissues engineering, skin grafting, medical adhesive, immobilization systems and textiles (Saha et al, 2011;Espevik & Sejak-Braek, 1996), for wound dressing application (Meng, Tian, & Yang, 2010;Kim et.al., 1999), pervaporation dehydration processes (Huang & Moon, 1999), biocatalysts in immobilization systems for ethanol manufacturing (Torres et al, 1998), wastewater purification (Torres, Sanchez-de-la-Vega, Bettran, & Jimenez, 1998), and for removal of toxic heavy metal cations (Nita et al, 2007;Wu, Mimura, & Niibori, 2009 ).…”