Microgels Formed by Spontaneous Click Chemistries Utilizing Microfluidic Flow Focusing for Cargo Release in Response to Endogenous or Exogenous Stimuli.

Protein therapeutics have become increasingly popular for the treatment of a variety of diseases owing to their specificity to targets of interest. However, challenges associated with them have limited their use for a range of ailments, including the limited options available for local controlled delivery. To address this challenge, degradable hydrogel microparticles, or microgels, loaded with model biocargoes were created with tunable release profiles or triggered burst release using chemistries responsive to endogenous or exogeneous stimuli, respectively. Specifically, microfluidic flow-focusing was utilized to form homogenous microgels with different spontaneous click chemistries that afforded degradation either in response to redox environments for sustained cargo release or light for on-demand cargo release. The resulting microgels were an appropriate size to remain localized within tissues upon injection and were easily passed through a needle relevant for injection, providing means for localized delivery. Release of a model biopolymer was observed over the course of several weeks for redox-responsive formulations or triggered for immediate release from the light-responsive formulation. Overall, we demonstrate the ability of microgels to be formulated with different materials chemistries to achieve various therapeutic release modalities, providing new tools for creation of more complex protein release profiles to improve therapeutic regimens.