Monolithic gelation of chitosan solutions via enzymatic hydrolysis of urea

• Published in: Carbohydrate polymers Vol. 64; no. 3; pp. 419 - 424
• Main Authors: Chenite, A., Gori, S., Shive, M., Desrosiers, E., Buschmann, M.D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 30-05-2006; Elsevier Science
• Subjects: Applied sciences; chemical concentration; Chitosan; Exact sciences and technology; gelation; hydrocolloids; hydrolysis; Monolithic hydrogel; Natural polymers; pH-induced gelation; phase transition; Physicochemistry of polymers; rheological properties; Rheology; solutions; Sol–gel transition; Starch and polysaccharides; urea; urease; pH-induced gelation; Chitosan; Monolithic hydrogel; Rheology; Sol–gel transition; Viscoelasticity; Sol-gel transition; Gelation; Enzymatic hydrolysis; Temperature effect; Physical gel; Experimental study; Urea; pH; Oside polymer; Kinetics; Hydrogel; Aqueous solution
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2005.12.010

A novel process for the formation of physical hydrogels of chitosan from injectable aqueous solutions is investigated. Uniform neutralization of chitosan solutions with ammonia generated in situ from enzymatic hydrolysis of urea is shown to produce pH-induced hydrogels with monolithic and homogeneous coherent 3D structure. Hydrogel formation was characterized by rheology. We found that the gelation time decreases as temperature increases from 15 to 45
°C as a consequence of synergistic effect of increased reactant diffusion and increased urease activity (maximum activity at 37
°C). The effects of urea and urease concentration are also presented.