(674a) Dynamic Covalent Hydrogels As Responsive Biomaterials

Authors: 
Tibbitt, M. W., University of Colorado
Marco-Dufort, B., ETH Zürich
Recent efforts in the design and fabrication of polymer networks have emphasized a class of soft matter based on dynamic covalent chemistry, which combines the mechanical properties of both physically and chemically cross-linked materials [1]. Dynamic covalent networks (DCNs) produce responsive, moldable, and self-healing materials, due to the reversible covalent bonds that break and reform on experimental timescales. Increasingly, these DCNs are being investigated as responsive biomaterials for a range of applications as viscoelastic cell culture platforms, materials for 3D bioprinting, and drug delivery technologies. This requires that the backbone and linkage chemistries be tolerated by biological systems and that the reversible properties of the networks can be controlled in aqueous environments. In this work, we exploit boronic ester bonds to assemble DCNs as responsive hydrogels. Critical to their use, we present a thorough investigation of how network topology and environmental conditions influence material properties, e.g., plateau modulus and relaxation time. In addition, we relate chemical detail from experimental and modeling techniques to the macroscale properties of the materials toward structure-function property relations in these materials. We exploit the DCNs as a platform technology for the thermal stabilization of a range of biomacromolecules.Many biomolecules are damaged upon exposure to thermal stress and the distribution around the world of vaccines, biotherapeutics, and proteins relies on an integrated cold chain (2–8 °C) from the point of manufacture to the point of use.[2] Our data demonstrates that direct encapsulation within DCNs can be used as excipients to avoid the need for a continuous cold chain and enable on-demand release at the point of use. Overall, the presentation will present a robust understanding of how dynamic covalent materials can be leveraged for biomedical applications.

References:

[1] B. Marco-Dufort and M.W. Tibbitt, Mater. Today Chem. 2019, 12, 16–33.

[2] B.V. Sridhar, J.R. Janczy, Ø. Hatlevik, G. Wolfson, K.S. Anseth, and M.W. Tibbitt, Biomacromolecules 2018, 19, 740–747.