Microgels are traditionally formed from synthetic polymers, and elaborate architectures, such as core/shell or Janus type morphologies, typically require tedious multistep reaction pathways. Here, we embark on an entirely different way and use pathway complexity in self-assembling DNA multiblock copolymer systems to structure metastable all-DNA microgels with complex architectures using a controlled heating pathway. The resulting architectures include simple microgels, microgel capsules and most importantly core/shell microgels with tunable dynamics of the encapsulated DNA. Interesting protocell architectures with liquid DNA encapsulated in a hydrogel DNA shell can be prepared and varied to the extent to change the internal dynamics to a full core/shell microgel/microgel structure. Origin of this complex phase behavior is the fact that we discovered a DNA LCST phenomenon (the polymer character), which can be overlaid with classical DNA hybridization (the supramolecular character). Both processes - phase segregation and hybridization - oppose each other during heating and cooling, and act on vastly different time, energy, and length scales. Based on elaborate kinetic control over these parameters it is possible to develop outstandingly defined and diverse morphologies. We finally show that even plasmonic nanoparticles can be integrated to achieve photothermal and spatiotemporally controlled release of DNA of core/shell microgel capsules, and demonstrate approaches for condensation into cellular hydrogels. The emphasis of this talk will be on the fundamental elucidation of the kinetics, pathway control and structural diversity of this new type of hierarchically structure DNA microgels.

Pathway-controlled complexity of metastable DNA microgels based on sequence-defined multiblock copolymers

255th National Meeting (2018)

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