The anisotropy in the shape of polymeric particles has been demonstrated to have many advantages over spherical particulates, including bio‐mimetic behavior, shaped‐directed flow, deformation, surface adhesion, targeting, motion, and permeability. The layer‐by‐layer (LbL) assembly is uniquely suited for synthesizing anisotropic particles as this method allows for simple and versatile replication of diverse colloid geometries with precise control over their chemical and physical properties. This review highlights recent progress in anisotropic particles of micrometer and nanometer sizes produced by a templated multilayer assembly of synthetic and biological macromolecules. Synthetic approaches to produce capsules and hydrogels utilizing anisotropic templates such as biological, polymeric, bulk hydrogel, inorganic colloids, and metal–organic framework crystals as sacrificial templates are overviewed. Structure‐property relationships controlled by the anisotropy in particle shape and surface are discussed and compared with their spherical counterparts. Advances and challenges in controlling particle properties through varying shape anisotropy and surface asymmetry are outlined. The perspective applications of anisotropic colloids in biomedicine, including programmed behavior in the blood and tissues as artificial cells, nano‐motors/sensors, and intelligent drug carriers are also discussed.
Granular hydrogels have emerged as a new class of injectable and porous biomaterials that improve integration with host tissue when compared to solid hydrogels. Granular hydrogels are typically prepared using spherical particles and this study considers whether particle shape (i.e., isotropic spheres vs anisotropic rods) influences granular hydrogel properties and cellular invasion. Simulations predict that anisotropic rods influence pore shape and interconnectivity, as well as bead transport through granular assemblies. Photo‐cross‐linkable norbornene‐modified hyaluronic acid is used to produce spherical and rod‐shaped particles using microfluidic droplet generators and formed into shear‐thinning and self‐healing granular hydrogels, with particle shape influencing mechanics and injectability. Rod‐shaped particles form granular hydrogels that have anisotropic and interconnected pores, with pore size and number influenced by particle shape and degree of packing. Robust in vitro sprouting of endothelial cells from embedded cellular spheroids is observed with rod‐shaped particles, including higher sprouting densities and sprout lengths when compared to hydrogels with spherical particles. Cell and vessel invasion into granular hydrogels when injected subcutaneously in vivo are significantly greater with rod‐shaped particles, whereas a gradient of cellularity is observed with spherical particles. Overall, this work demonstrates potentially superior functional properties of granular hydrogels with rod‐shaped particles for tissue repair.
more » « less- NSF-PAR ID:
- 10364417
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 34
- Issue:
- 12
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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