Macroporous methacrylated hyaluronic acid cryogels of high mechanical strength and flow-dependent viscoelasticity

We present here a new approach for the fabrication of macroporous hyaluronic acid (HA) cryogels with a tunable porous structure, flow-dependent viscoelasticity, and a high mechanical strength. They were synthesized from methacrylated HA in aqueous solutions at −18 °C by free-radical mechanism using in situ prepared poly(N, N-dimethylacrylamide) (PDMAA) as a spacer. Both the porosity and the average diameter of the pores decrease from 99 to 90% and from 150 to 90 μm, respectively, with increasing PDMAA content of the cryogels due to the simultaneous decrease in the amount of ice template during cryogelation. The cryogels also exhibit reversible strain-dependent apparent gel-to-sol transition due to the flowing-out and flowing-in water through the pores. This flow-dependent viscoelasticity is of great interest as it protects HA network from damage under large strain and hence acts as a self-defense mechanism.