Collagen–Poly(<i>N</i>‑isopropylacrylamide)\nHydrogels with Tunable Properties

Abstract

There\nis a lack of hydrogel materials whose properties can be tuned\nat the point of use. Biological hydrogels, such as collagen, gelate\nat physiological temperatures; however, they are not always ideal\nas scaffolds because of their low mechanical strength. Their mechanics\ncan be improved through cross-linking and chemical modification, but\nthese methods still require further synthesis. We have demonstrated\nthat by combining collagen with a thermoresponsive polymer, poly­(<i>N</i>-isopropylacrylamide) (PNIPAM), the mechanical properties\ncan be improved while maintaining cytocompatibility. Furthermore,\ndifferent concentrations of this polymer led to a range of hydrogels\nwith shear moduli ranging from 10⁵ Pa down to less than\n10² Pa, similar to the soft tissues in the body. In addition\nto variable mechanical properties, the hydrogel blends have a range\nof micron-scale structures and porosities, which caused adipose-derived\nstromal cells (ADSCs) to adopt different morphologies when encapsulated\nwithin and may therefore be able to direct cell fate.