Biopolymer networks packed with microgels combine strain stiffening and shape programmability
Vignesh Subramaniam,
Abhishek M. Shetty,
Steven J. Chisolm,
Taylor R. Lansberry,
Anjana Balachandar,
Cameron D. Morley,
Thomas E. Angelini
Affiliations
Vignesh Subramaniam
University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA
Abhishek M. Shetty
Advanced Technical Center, Anton Paar USA, Ashland, VA, 23005, USA
Steven J. Chisolm
University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA
Taylor R. Lansberry
University of Florida, Herbert Wertheim College of Engineering, J. Crayton Pruitt Family Department of Biomedical Engineering, Gainesville, FL, 32611, USA
Anjana Balachandar
Stanford University, Department of Bioengineering, Stanford, CA, 94305, USA
Cameron D. Morley
University of California Berkeley, Department of Bioengineering, Berkeley, CA, 94720, USA
Thomas E. Angelini
University of Florida, Herbert Wertheim College of Engineering, Department of Mechanical and Aerospace Engineering, Gainesville, FL, 32611, USA; University of Florida, Herbert Wertheim College of Engineering, J. Crayton Pruitt Family Department of Biomedical Engineering, Gainesville, FL, 32611, USA; University of Florida, Herbert Wertheim College of Engineering, Department of Materials Science and Engineering, Gainesville, FL, 32611, USA; Corresponding author.
Biomaterials that can be reversibly stiffened and shaped could be useful in broad biomedical applications where form-fitting scaffolds are needed. Here we investigate the combination of strong non-linear elasticity in biopolymer networks with the reconfigurability of packed hydrogel particles within a composite biomaterial. By packing microgels into collagen-1 networks and characterizing their linear and non-linear material properties, we empirically determine a scaling relationship that describes the synergistic dependence of the material's linear elastic shear modulus on the concentration of both components. We perform high-strain rheological tests and find that the materials strain stiffen and also exhibit a form of programmability, where no applied stress is required to maintain stiffened states of deformation after large strains are applied. We demonstrate that this non-linear rheological behavior can be used to shape samples that do not spontaneously relax large-scale bends, holding their deformed shapes for days. Detailed analysis of the frequency-dependent rheology reveals an unexpected connection to the rheology of living cells, where models of soft glasses capture their low-frequency behaviors and polymer elasticity models capture their high-frequency behaviors.
