Dynamically Reconfigurable Micro-Patterned Hydrogels Based on Magnetic Pickering Emulsion Droplets

Abstract

Reconfigurability within hydrogels has emerged as an attractive functionality that can be used in information encryption, cargo/delivery, environmental remediation, soft robotics, and medicine. Here micro-patterned polymer hydrogels capable of temperature-dependent reconfigurability are fabricated. For this, the hydrogels are provided with micron-sized Pickering emulsion droplets stabilized by magnetic particles, which are capable of harnessing energy from external force fields. The droplets can both migrate under magnetic field gradients and heat the environment when laser irradiated. These functions not only affect a single compartment but have higher-order effects on the mesoscale, thanks to the temperature-responsiveness of the polymeric network. This double responsiveness is exploited to control the spatial organization of hundreds of droplets within the hydrogel matrix and form predesigned and sophisticated patterns. Furthermore, pattern self-reconfiguration driven by the droplets themselves upon laser irradiation is induced. Finally, we show that due to their internal liquid phase, the droplets can be used as reservoirs of hydrophobic nutrients for living cells (i.e., Yarrowia lipolytica yeast) in the solid-like environment of the polymeric network, and demonstrate communication between the droplets and the cells to facilitate nutrient uptake. Altogether, the results provide opportunities for the development of stimuli-sensitive polymer hydrogels with post-synthesis reprogrammable response using micro-compartments as building blocks.

Keywords: hydrogels; magnetic field‐responsiveness; micro‐compartments; self‐reconfigurability; temperature‐responsive polymer.