Responsive hydrogels that undergo controlled shape changes in response to a range of stimuli are of interest for microscale soft robotic and biomedical devices. However, these applications require fabrication methods capable of preparing complex, heterogeneous materials. Here we report a new approach for making patterned, multi-material and multi-responsive hydrogels, on a micrometre to millimetre scale. Nanolitre aqueous pre-gel droplets were connected through lipid bilayers in predetermined architectures and photopolymerized to yield continuous hydrogel structures. By using this droplet network technology to pattern domains containing temperature-responsive or non-responsive hydrogels, structures that undergo reversible curling were produced. Through patterning of gold nanoparticle-containing domains into the hydrogels, light-activated shape change was achieved, while domains bearing magnetic particles allowed movement of the structures in a magnetic field. To highlight our technique, we generated a multi-responsive hydrogel that, at one temperature, could be moved through a constriction under a magnetic field and, at a second temperature, could grip and transport a cargo.
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The data that support the findings of this study are available from the corresponding author upon reasonable request.
The MATLAB code used for image analysis in this study is available from the corresponding author upon reasonable request.
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This research was supported by a European Research Council Advanced Grant and OxSyBio. F.G.D. and R.G.K. were supported by funding from the EPSRC & BBSRC Centre for Doctoral Training in Synthetic Biology (EP/L016494/1). D.J.L. is grateful to the European Union’s Horizon 2020 research and innovation programme for a Marie Curie Global Fellowship (657650). D.J.L. and C.J.H. acknowledge support from the US Army Research Office under contracts W911NF-09-D-0001 and W911NF-19-D-0001 for the Institute for Collaborative Biotechnologies. M.J.B. was supported by Merton College. J.B.S. was supported by funding from the Biotechnology and Biological Sciences Research Council (BB/M011224/1).
H.B. is the Founder, a Director, a share-holder and a consultant for OxSyBio, a company engaged in the development of printed tissues and tissue-like materials. The other authors declare no competing interests.
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Downs, F.G., Lunn, D.J., Booth, M.J. et al. Multi-responsive hydrogel structures from patterned droplet networks. Nat. Chem. 12, 363–371 (2020). https://doi.org/10.1038/s41557-020-0444-1