title: A novel strategy for preparing mechanically robust ionically cross-linked alginate hydrogels.
abstract: The properties of alginate films modified using two cross-linker ions (Ca(2+) and Ba(2+)), comparing two separate cross-linking techniques (the traditional immersion (IM) method and a new strategy in a pressure-assisted diffusion (PD) method), are evaluated. This was achieved through measuring metal ion content, water uptake and film stability in an ionic solution ([Ca(2+)] = 2 mM). Characterization of the internal structure and mechanical properties of hydrated films were established by cryogenic scanning electron microscopy and tensile testing, respectively. It was found that gels formed by the PD technique possessed greater stability and did not exhibit any delamination after 21 day immersion as compared to gels formed by the IM technique. The Ba(2+) cross-linked gels possessed significantly higher cross-linking density as reflected in lower water content, a more dense internal structure and higher Young's modulus compared to Ca(2+) cross-linked gels. For the Ca(2+) cross-linked gels, a large improvement in the mechanical properties was observed in gels produced by the PD technique and this was attributed to thicker pore walls observed within the hydrogel structure. In contrast, for the Ba(2+) cross-linked gels, the PD technique resulted in gels that had lower tensile strength and strain energy density and this was attributed to phase separation and larger macropores in this gel.
authors: School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors: Aparna
authors: A
authors: Jejurikar
authors: Gwen
authors: G
authors: Lawrie
authors: Darren
authors: D
authors: Martin
authors: Lisbeth
authors: L
authors: Grøndahl
mesh_terms: D000464:Alginates / Q000737:chemistry*; D001464:Barium / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry*; D020285:Cryoelectron Microscopy / Q000379:methods; D004058:Diffusion; D005782:Gels / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D007477:Ions; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008956:Models, Chemical; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013718:Tensile Strength
chemical_list: D000464:Alginates; D003432:Cross-Linking Reagents; D005782:Gels; D006603:Hexuronic Acids; D020100:Hydrogels; D007477:Ions; D001464:Barium; D020723:Glucuronic Acid; D002118:Calcium