Chitosan-calcium alginate hydrogels

Biomimetic mineralization of aqueous carbonate ions into chitosan-calcium alginate hydrogels... 

Two hydrogels of calcium alginate and chitosan-calcium alginate composite were prepared from Na alginate and its composite with chitosan by soaking in O.IM aq. CaCla. A biomimic fixation of aqueous COa - ions as CaCOa was performed. Each of the hydrogels was put into a dialysis membrane tube, and was soaked in 0.1 M aq. NaaCOa (pH 11) at room temperature for 1 day to afford a white precipitate of CaCOa or chitosan-CaCOa and a water-soluble sodium alginate. The dry chitosan-CaCOs composite (60% chitosan and 23% COa -) was stable in aqueous alkaline solutions and unstable in aqueous acidic solutions. 

K. Lee, J. Yoon, J. Lee, S. Kim, H. Jung, S. Kim, et al.. Sustained release of vascular endothelial growth factor from calcium-induced alginate hydrogels reinforced by heparin and chitosan. Transplant. Proc. 36 (8) (2004) 2464-2465. 

Peng P et al (2008) Concurrent elution of calcium phosphate and macromolecules from alginate/chitosan hydrogel coatings. Biointerphases 3(4) 105-116... 

This vibration system involves a Turbotak air-atomizer in which a pressurized air is injected to mix with the sodium alginate solution. Pressurized air forces the minute liquid droplets out through the orifice of a nozzle and is sprayed into the calcium chloride solution. When these droplets come in contact with calcium chloride solution, calcium ions diffuses into the droplets of sodium alginate, which leads to form microgel droplets. Hydrogel particles thus formed can be further reinforced by poly-L-lysine or chitosan to form a membrane on the droplets. The particle size of hydrogel beads can be obtained in the range of 5 and 15 pm by the use of air atomization technique. ... 

Y.-H. Lin, et al, Physically crosslinked alginate/N,0-carboxymethyl chitosan hydrogels with calcium for oral delivery of protein drugs. Biomaterials, 26 (14) 2105-2113, 2005. 

---