Formation and characterisation of a modifiable soft macro-porous hyaluronic acid cryogel platform

A facile method for the synthesis of cell supportive, highly macro-porous hyaluronic acid (HA) hydrogels via cryogelation is presented. Unmodified HA was chemically cross-linked via EDC/NHS zero-length cross-linking at sub-zero temperatures to yield cryogels with high porosity and high pore interconnectivity. The physical properties of the HA cryogels including porosity, average pore size, elasticity and swelling properties were characterised as a function of cryogelation conditions and composition of the precursor solution. The HA cryogels swell extensively in water, with the average porosities observed being ~90% under all conditions explored. The morphology of the cryogels can be controlled, allowing scaffolds with an average pore size ranging from 18 ± 2 to 87 ± 5 μm to be formed. By varying the cross-linking degree and HA concentration, a wide range of bulk elastic properties can be achieved, ranging from ~1 kPa to above 10 kPa. Preliminary cell culture experiments, with NIH 3T3 and HEK 293 cell lines, performed on biochemically modified and unmodified gels show the cryogels support cell proliferation and cell interactions, illustrating the biomedical potential of the platform.