Comparing Extrusion Fragmentation and Microfluidic Droplet Generation for Tunable Hyaluronic Acid based Microgels

• Bethany Watkins, Biomedical Engineering, University of Delaware

• Robert Oakes, Biomedical Engineering, University of Delaware

Hydrogels are polymer-based biomaterials that emulate the structure and mechanical properties of the extracellular matrix, making them valuable for fields like tissue engineering, 3D cell culture, and bioprinting. Granular hydrogels, also known as microgels, offer advantageous properties over traditional bulk hydrogels, including improved injectability, porosity, and tunability of rheological and biochemical properties. Characteristics such as spherical dispersity, uniformity, size, and storage modulus play a key role in evaluating the functionality of the microgels. Tuning these factors for different implantation sites and tissue densities is vital to improve cell infiltration, tissue integration, and immune response upon implantation. In this study, we used norbornene-functionalized hyaluronic acid (NorHA) as the microgel polymer because of its efficient photo crosslinking chemistry and highly customizable mechanical properties. We aim to evaluate and compare the two fabrication methods for producing NorHA microgels: extrusion fragmentation and microfluidic droplet generation. Microgels from both groups were assessed for size distribution, circularity, and rheological properties over a 72-hour time period. By directly comparing these fabrication strategies, this work provides insight into the differences between fabrication methods to assess simplicity, particle uniformity, and mechanical characteristics.