Patterning of anisotropic physical cues in granular PEG hydrogel composites using magnetic templating

Granular hydrogels represent an important advancement in hydrogel biomaterials for tissue engineering. These granular materials hold advantages over the traditionally formulated hydrogel because the constituent microgels add modularity and a high degree of porosity upon assembly. While granular hydrogels have shown great promise in tissue engineering, their increased porosity is still randomly distributed, unlike the structure of tissues like nerve which possess an anisotropic or hierarchical degree of porosity. We have developed and utilized a technique termed magnetic templating which allows the micropatterning of aligned sacrificial magnetic porogens that can be then removed upon hydrogel crosslinking, leaving an aligned pore architecture. Here we demonstrate the feasibility of magnetic templating of scaffolds consisting of synthetic polymer within a granular hydrogel system. To do so, we evaluated the extent to which microgel concentration impacts the rheology of jammed granular gels and utilized nano computed tomography to evaluate its concomitant influence on the degree of porogen chain alignment. Lastly, we show that the porogens are effectively cleared from templated granular hydrogels. This work establishes proof-of-concept for using magnetic templating to impart highly anisotropic structure within granular PEG hydrogel composites, with potential applications in regenerative medicine and tissue engineering.