A new tool to produce alginate-based aerogels for medical applications, by supercritical gel drying

Alginate-based aerogels with a cylindrical shape to be used for medical applications were produced by supercritical drying. First, alginate (Alg) solutions at different polymer concentrations (from 5% to 15% w/w) were extruded using a new custom-made device, in a coagulation bath of CaCl2 at 5% w/w or CuSO4 at 1.5% w/v, where hydrogels were generated; then, the corresponding aerogels were produced by supercritical drying at 200 bar and 45 °C for 4 h. Scanning electron microscopy showed that nanostructured morphology of native Ca- and Cu-Alg-hydrogels was preserved by supercritical drying. The same apparatus was also tested to produce alginate-chitosan (Alg-Ch) aerogels; they showed an hybrid morphology characterized by the microporosity of chitosan and the nanofibers of alginate, homogeneously distributed in the gel structure.