Hydrolytically Degradable Poly(ethylene glycol) Hydrogel as a Tunable Scaffold for Neural Tissue Engineering

The objective of this work was to create 3D hydrogel matrices with defined mechanical properties, as well as tunable degradability for use in applications involving protein delivery and cell encapsulation in neural tissue engineering. Thus, we report the synthesis and characterization of a novel hydrolytically degradable poly(ethylene glycol) (PEG) hydrogel composed of PEG vinyl sulfone (PEG-VS) cross-linked with PEGdiester-dithiol. Unlike previously reported degradable PEG-based hydrogels, these materials are homogeneous in structure, fully hydrophilic and have highly specific cross-linking chemistry. We characterized hydrogel degradation and associated trends in mechanical properties, i.e., storage modulus, swelling ratio, and mesh size. Degradation time and the monitored mechanical properties of the gel correlated with cross-linker molecular weight, cross-linker functionality, and total polymer density. The hydrogels were covalently modified with several cell adhesive peptides and the subsequent changes in hydrogel mechanical properties with were further investigated. We will report our findings of neuronal response to these novel materials and their ability to promote neuronal viability and neurite outgrowth. These results will ultimately lead to a fundamental quantitative understanding of how to more effectively design tissue engineering scaffolds for directed neuronal response and may result in advanced model systems for in- vitro neurobiology studies as well as improved materials to treat neural injuries.