Abstract

Spatiotemporally Modifiable Hydrogels from Cellulose

William Gramlich, Assistant Professor, Department of Chemistry, University of Maine

Cellulose derivatives have long been used as hydrogel biomaterials due to their biocompatibility and wide availability, but these materials have traditionally had low modulus as the hydrogels are formed through physical entanglement. The limitations of physically crosslinked cellulose biomaterials have stymied their use in areas such as regenerative medicine and stem cell differentiation. Chemically crosslinked cellulose hydrogels alleviate these limitations, but require pendent reactive groups off cellulose, which typically necessitates using organic solvents to functionalize these molecules. In this work, cellulose derivatives such as carboxymethyl cellulose (CMC) and cellulose nanofibrils (CNF) have been functionalized with pendent groups that allow for spatiotemporal modification of the hydrogel properties.  Norbornene-functionalized CMC and CNF have been crosslinked through radical initiated thiol-ene click chemistry with a variety of dithiol crosslinkers. By selecting crosslinkers that are stimuli responsive, stimuli responsive cellulose hydrogels can be created. Using photopatterning and these stimuli responsive crosslinkers, hydrogels can be spatiotemporally modified in three-dimensions to introduce stimuli response in specific areas, affecting cell behavior.