Abstract:Micro-scale hydrogel particles, known as microgels, are used in industry to control the rheology of numerous different products, and are also used in experimental research to study the origins of jamming and glassy behavior in soft-sphere model systems. At the macro-scale, the rheological behaviour of densely packed microgels has been thoroughly characterized; at the particle-scale, careful investigations of jamming, yielding, and glassy-dynamics have been performed through experiment, theory, and simulation. … Show more
“…2g, Supplementary 5). The analysis confirmed that the geometric parameters (particle shape and porosity) dominate the high-strain behaviors 33 of yielding ( in Fig. 2f and 2g) and the soft plateau ( ), important for shaping and injection.…”
Section: Fig 2 In Silico Simulation and Design Of The Epi Biomaterisupporting
confidence: 63%
“…3d). As expected for an essentially non-frictional 33 Our next aim was precise mechanical matching to adipose tissue 12,13 , while conserving a pore size greater than 50μm required for vascularization 34,35 . Fig.…”
Section: Synthesis and Mechanical Characterizationmentioning
We present a novel type of injectable biomaterial with an elastic softening transition.The material enables in-vivo shaping, followed by induction of 3D stable vascularized tissue adopting the desired shape. We establish the necessary geometrical and physical parameters by extensive numerical simulation. Irregular particle shape dramatically enhances yield strain for in-vivo stability against deformation, while friction and porosity provide the elastic softening transition as an emergent meta-material property.Accordingly, we synthesize our injectable meta-biomaterial as a suspension of irregularly fragmented, highly porous sponge-like microgels. The meta-biomaterial exhibits both high yield strain, and the desired novel elastic softening transition for in-
“…2g, Supplementary 5). The analysis confirmed that the geometric parameters (particle shape and porosity) dominate the high-strain behaviors 33 of yielding ( in Fig. 2f and 2g) and the soft plateau ( ), important for shaping and injection.…”
Section: Fig 2 In Silico Simulation and Design Of The Epi Biomaterisupporting
confidence: 63%
“…3d). As expected for an essentially non-frictional 33 Our next aim was precise mechanical matching to adipose tissue 12,13 , while conserving a pore size greater than 50μm required for vascularization 34,35 . Fig.…”
Section: Synthesis and Mechanical Characterizationmentioning
We present a novel type of injectable biomaterial with an elastic softening transition.The material enables in-vivo shaping, followed by induction of 3D stable vascularized tissue adopting the desired shape. We establish the necessary geometrical and physical parameters by extensive numerical simulation. Irregular particle shape dramatically enhances yield strain for in-vivo stability against deformation, while friction and porosity provide the elastic softening transition as an emergent meta-material property.Accordingly, we synthesize our injectable meta-biomaterial as a suspension of irregularly fragmented, highly porous sponge-like microgels. The meta-biomaterial exhibits both high yield strain, and the desired novel elastic softening transition for in-
“…The dependence of λ on G ’ indicates that the microgel pack is deformed elastically and not yielded during buckling. However, if microgel creep occurs over the long time-scale associated with the process, we expect the slow rearrangement of the microgels to occur at constant packing density 20 .Fig. 3Determining the microbeam moduli to predict λ .…”
Section: Resultsmentioning
confidence: 99%
“…Lightly cross-linked polyacrylamide microgels with 17 mol% methacrylic acid as an ionizable comonomer are prepared 20,42 . A solution of 8% (w/w) acrylamide, 2% (w/w) methacrylic acid, 1% (w/w) poly(ethylene glycol) diacrylate (MW = 700 g mol −1 ), and 0.1% (w/w) azobisisobutyronitrile in ethanol (490 mL) is prepared.…”
With improving biofabrication technology, 3D bioprinted constructs increasingly resemble real tissues. However, the fundamental principles describing how cell-generated forces within these constructs drive deformations, mechanical instabilities, and structural failures have not been established, even for basic biofabricated building blocks. Here we investigate mechanical behaviours of 3D printed microbeams made from living cells and extracellular matrix, bioprinting these simple structural elements into a 3D culture medium made from packed microgels, creating a mechanically controlled environment that allows the beams to evolve under cell-generated forces. By varying the properties of the beams and the surrounding microgel medium, we explore the mechanical behaviours exhibited by these structures. We observe buckling, axial contraction, failure, and total static stability, and we develop mechanical models of cell-ECM microbeam mechanics. We envision these models and their generalizations to other fundamental 3D shapes to facilitate the predictable design of biofabricated structures using simple building blocks in the future.
“…At low shear rates, the shear stress is constant and independent of shear rate, indicating a non-zero yield stress (~1 to 10 Pa) characteristic of a solid material. At higher shear rates, however, the shear stress follows a power law dependence on shear rate, indicating that the solid matrix becomes fluidized-the individual hydrogel particles rearrange with respect to each other and the medium yields (20). This feature enables us to 3D-print populations within the pore space in defined architectures.…”
Chemotactic migration of bacteria—their ability to direct multicellular motion along chemical gradients—is central to processes in agriculture, the environment, and medicine. However, studies are typically performed in bulk liquid, despite the fact that most bacteria inhabit heterogeneous porous media such as soils, sediments, and biological gels. Here, we directly visualize the migration of E. coli populations in 3D porous media. We find that pore-scale confinement is a strong regulator of chemotactic migration. Strikingly, cells use a different primary mechanism to direct their motion in confinement than in bulk liquid. Further, confinement markedly alters the dynamics and morphology of the migrating population—features that can be described by a continuum model, but only when standard motility parameters are substantially altered from their bulk liquid values. Our work thus provides a framework to predict and control the migration of bacteria, and active matter in general, in heterogeneous environments.
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