Date of Award
Winter 2025
Project Type
Dissertation
Program or Major
Chemistry
Degree Name
Doctor of Philosophy
First Advisor
Nate J Oldenhuis
Second Advisor
Charles K Zercher
Third Advisor
Brittany M White-Mathieu
Abstract
Hydrogels have become an indispensable tool for studying and engineering cellular microenvironments, yet most synthetic systems remain limited by static network structures, poorly controlled degradation, or reliance on reactive groups that are incompatible with long-term biological applications. These constraints hinder our ability to build materials that accurately recapitulate the dynamic nature of the extracellular matrix (ECM). This work seeks to expand the utility of hydrogel-based ECM mimics by advancing the underlying chemistry to achieve improved degradation control, cleaner and more selective crosslinking strategies, and multi stimuli-responsive networks that more closely mirror the complexity of living tissues.
To address limitations in existing degradable scaffolds, we first evaluated dextran methacrylate (Dex-MA) hydrogels to assess how enzymatic and hydrolytic degradation influences long-term culture performance. Prior work with MMP-cleavable peptides and 3D fibroblast cultures established that Dex-MA scaffolds degrade more rapidly than cells produce ECM, ultimately compromising structural support. Motivated by these limitations, we explored the design of hydrolytically stable, amide-linked dextrans with high degrees of substitution. Although our exploration of epoxide ring opening, alkyl halide substitution, and carboxymethyl-mediated coupling revealed significant constraints on polysaccharide functionalization, this work helped improve the synthetic routes needed for next-generation dextran hydrogels with independently tunable degradation pathways.
We next developed a penicillamine-derived β-thiolactone platform that overcomes longstanding limitations of native chemical ligation (NCL). This system enables rapid, spontaneous gelation in fully aqueous media, eliminates toxic and malodorous byproducts, and selectively targets N-terminal cysteine over competing biological thiols. Using this chemistry, we generated polyethylene glycol (PEG) hydrogels that support both 2D spreading and 3D encapsulation, offering a scalable, inexpensive, and bioorthogonal alternative to traditional thiol-Michael, strain-promoted azide–alkyne cycloaddition (SPAAC), and inverse electron-demand Diels–Alder (IEDDA) strategies.
Building on this foundation, we created multi stimuli-responsive PEG networks that couple the thermal and pH-dependent equilibrium behavior with orthogonal NVOC photodeprotection. These materials remain reversibly assembled until light exposure triggers covalent rearrangement, permanently locking the gel. Such control enables spatial and temporal manipulation of network mechanics and topology, more closely aligning synthetic scaffolds with ECM dynamics.
Together, these studies outline a chemical platform for creating adaptive, biocompatible, and tunable hydrogels suitable for 3D culture and investigations of cell–matrix interactions. These results also open opportunities to apply β-thiolactone NCL to additional biopolymers and to use photopatterning to generate heterogeneous scaffolds that more closely reflect native tissue structure.
Recommended Citation
Currier, Matthew Edward, "From Bioinspired Matrices to Multi-Responsive Networks: Advancing Materials Through Chemistry" (2025). Doctoral Dissertations. 2973.
https://scholars.unh.edu/dissertation/2973