Complex Tuning of Physical Properties of Hyperbranched Polyglycerol-Based Bioink for Microfabrication of Cell-Laden Hydrogels

Microfabrication technology has emerged as a valuable tool for fabricating structures with high resolution and complex architecture for tissue engineering applications. For this purpose, it is imperative to develop bioink that can be readily converted to a solid structure by the modus operandi of a chosen apparatus, while optimally supporting the biological functions by tuning their physicochemical properties. Herein, a photocrosslinkable hyperbranched polyglycerol (acrylic hyperbranched glycerol (AHPG)) is developed as a crosslinker to fabricate cell-laden hydrogels. Due to its hydrophilicity as well as numerous hydroxyl groups for the conjugation of reactive functional groups (e.g., acrylate), the mechanical properties of resulting hydrogels could be controlled in a wide range by tuning both molecular weight and degree of acrylate substitution of AHPG. The control of mechanical properties by AHPG is highly dependent on the type of monomer, due to the hydrophilic/hydrophobic balance of polyglycerol backbone and acrylate as well as the dynamic conformational flexibility based on the molecular weight of polyglycerol. The cell encapsulation studies demonstrate the biocompatibility of the AHPG-linked hydrogels. Eventually, the AHPG-based hydrogel precursor solution is employed as a bioink for a digital light processing based printing system to generate cell-laden microgels with various shapes and sizes for tissue engineering applications.