Composite Microgels with Dynamically Switchable Stiffness

Whereas macroscopic hydrogels with precisely controllable and dynamically adjustable properties do exist, the development of similar platforms at the microscale is much more challenging. Here, we introduce a novel composite microgel system comprising the two cytocompatible biopolymers alginate and mucin, which are functionalized to simultaneously enable covalent and ionic cross-linking. As a consequence, the initial stiffness of the generated microgels can not only be tailored over a range from ∼350 Pa to ∼7 kPa, but it is also possible to first increase and then decrease the microgel stiffness on demand at any time point post-production. Owing to the two distinct biopolymer components in the microgels, they can be enzymatically degraded and resist biofouling events by bacteria. With this set of properties, this microgel system should be highly suitable for versatile applications in bioengineering or mechanobiology.