Formation of defined microporous 3D-structures starting from cross-linked hydrogels

A new and simple technique was developed to obtain polysaccharide (hyaluronane, alginate and carboxymethylcellulose) -based hydrogels with a defined porous morphology. The technique consists of stratifying a cross-linked hydrogel on a filter with known pore diameter. CO2 bubbles, produced by the addition of HCl to a porogen salt NaHCO3, are forced to pass through the filter, and they induce the hydrogel to assume a porous morphology. The presence and distribution of pores was confirmed by scanning-electron microscopy (SEM). A strict correspondence was found between the porosity of the filter and the pore diameter in the hydrogels. Water uptake measurements showed a decreased amount of water taken up by the porous hydrogels compared with the native hydrogels, due to a compacting of the material. An explanation of the porous material properties of Hyal hydrogel was given on the basis of FTIR spectra.