From cholesteric nanocolloidal liquid crystals tonanofibrillar hydrogels

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• Prof. Eugenia Kumacheva (Department of Chemistry, University of Toronto, Canada)
• Friday 20 March 2020, 15:00-16:00
• This talk has been cancelled. .

If you have a question about this talk, please contact Lingtao Kong.

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Recent shift of the paradigm from the organization of colloids in liquid crystals to liquid crystals formed by colloidal particles has stimulated revived interest in cellulose nanocrystals (CNCs), biocompatible and sustainable rod-shape nanoparticles. This presentation will highlight two aspects of CNC -related research in my group Self-assembly of CNCs. Nanoparticle organization in constrained geometries is an area of fundamental and practical importance, since under confinement, nanocolloids exhibit new self-assembly modes. We showed that under spherical confinement, cholesteric liquid crystals formed by CNCs exhibit new self-assembly modalities that, in turn, govern the organization of polymer, metal, carbon and metal oxide nanoparticles in well-defined and stable defects. The resulting hierarchical structures exhibit fluorescence, plasmonic properties, and magnetic actuation.1,2 Furthermore, we demonstrate interactive morphogenesis between the cholesteric CNC host and nanoparticle guests, which stems from the coupling of self-assembly modes of CNCs and guest nanoparticles.3 These results advance our understanding of how the interplay of order, confinement and topological defects affects soft matter materials. Hydrogels derived from CNCs. Synthesis of man-made hydrogels mimicking fibrous biological tissues is an important and challenging task. We developed CNC -based nanofibrillar hydrogel scaffolds for cell culture. One example of such a scaffold is a temperature-responsive hydrogel formed by CNCs end-tethered with polymer molecules. A cell-laden hydrogel formed at 37 oC from an aqueous CNC suspension to support cancer organoid growth. On demand, the organoids were released by reducing the temperature and transferred to another scaffold.4 Another CNC -derived hydrogel was 3D printed to achieve shear-induced CNC alignment and generate structurally anisotropic nanofibrillar hydrogel for replication of in vivo cellular environments.

(1) Y. Li, et al. Nature Comm. doi:10.1038/ncomms12520 (2019). (2) Y. Li, E. Prince, S. Cho, A. Salari, Y.M. Golestani, O.D. Lavrentovich, E. Kumacheva, Proc. Nat. Acad. Sci. U.S.A., 114, 2137-2142 (2017). (3) Y. Li, Y.; N. Khuu, E. Prince, M. Alizadehgiashi; E. Galati. O.D. Lavrentovich, E. Kumacheva, Science Advances 5, eaa1035 (2016). (4) Y. Li, et al. Angew. Chem. Int. Ed. 56, 6083-6087 (2017).

This talk is part of the Chemistry Departmental-wide lectures series.

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