Stop-flow lithography for the production of shape-evolving degradable microgel particles.

Microgel particles capable of bulk degradation have been synthesized from a solution of diacrylated triblock copolymer composed of poly(ethylene glycol) and poly(lactic acid) in a microfluidic device using stop-flow lithography (SFL). It has been previously demonstrated that SFL can be used to fabricate particles with precise control over particle size and shape. Here, we have fabricated hydrogel particles of varying size and shape and examined their mass-loss and swelling behavior histologically and mechanically. We report that these features, as well as degradation behavior of the hydrogel particles may be tailored with SFL. By reducing the applied UV dose during fabrication, hydrogel particles can be made to exhibit a distinct deviation from the classical erosion profiles of bulk-degrading hydrogels. At higher UV doses, a saturation in cross-linking density occurs and bulk-degrading behavior is observed. Finally, we synthesized multifunctional composite particles, providing unique features not found in homogeneous hydrogels.