Water–Hydrogel Binding Affinity Modulates Freeze-Drying-Induced Micropore Architecture and Skeletal Myotube Formation

Freeze-dried hydrogels are increasingly used to create 3D interconnected micropores that facilitate biomolecular and cellular transports. However, freeze-drying is often plagued by variance in micropore architecture based on polymer choice. We hypothesized that water-polymer binding affinity plays a significant role in sizes and numbers of micropores formed through freeze-drying, influencing cell-derived tissue quality. Poly(ethylene glycol)diacrylate (PEGDA) hydrogels with alginate methacrylate (AM) were used due to AM's higher binding affinity for water than PEGDA. PEGDA-AM hydrogels with larger AM concentrations resulted in larger sizes and numbers of micropores than pure PEGDA hydrogels, attributed to the increased mass of water binding to the PEGDA-AM gel. Skeletal myoblasts loaded in microporous PEGDA-AM hydrogels were active to produce 3D muscle-like tissue, while those loaded in pure PEGDA gels were localized on the gel surface. We propose that this study will be broadly useful in designing and improving the performance of various microporous gels.