Self-organized structural hierarchy in mixed polysaccharide sponges

Hierarchically structured polysaccharide sponges have been prepared by freeze drying of anisotropically ordered alginate–dextran hydrogels produced by dissipative densification in the presence of a uniaxial Ca2+ ion diffusion gradient. The freeze-dried gels exhibit elastic/viscoelastic properties, and consist of aligned micrometre-sized capillaries with complex wall structures comprising interconnected networks of helically ordered micropores. Magnetite or gold nanoparticles can be readily incorporated into the gels with retention of the patterned microstructure. The ability to fabricate such complex microstructures by facile processes should significantly extend the utility of soft materials in diverse encapsulation-based applications.