title: Generation of spatially aligned collagen fiber networks through microtransfer molding.
abstract: The unique biomechanical properties of native tissue are governed by the organization and composition of integrated collagen and elastin networks. An approach for fabricating spatially aligned, fiber-reinforced composites with adjustable collagen fiber dimensions, layouts, and distribution within an elastin-like protein matrix yielding a biocomposite with controllable mechanical responses is reported. Microtransfer molding is employed for the fabrication of hollow and solid collagen fibers with straight or crimped fiber geometries. Collagen fibers (width: 2-50 μm, thickness: 300 nm to 3 μm) exhibit a Young's modulus of 126 ± 61 MPa and an ultimate tensile strength of 7 ± 3.2 MPa. As fiber networks within composite structures, straight fiber layouts display orthotropic responses with Young's modulus ranging from 0.95 ± 0.35 to 10.4 ± 0.5 MPa and tensile strength from 0.22 ± 0.08 to 0.87 ± 0.5 MPa with increasing fraction of collagen fibers (1-10%, v/v). In contrast, composites based on crimped fiber layouts exhibit strain-dependent stiffness with an increase in Young's modulus from 0.7 ± 0.14 MPa to 3.15 ± 0.49 MPa, at a specific transition strain. Through controlling the microstructure of engineered collagen fiber networks, a facile means is established to control macroscale mechanical responses of composite protein-based materials.
authors.affiliation: Department of Surgery, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA, 02115, USA; Wyss Institute of Biologically Inspired, Engineering of Harvard University, Boston, MA, 02115, USA; School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
authors.forename: Nisarga
authors.initials: N
authors.lastname: Naik
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Caves
authors.forename: Elliot L
authors.initials: EL
authors.lastname: Chaikof
authors.forename: Mark G
authors.initials: MG
authors.lastname: Allen
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001696:Biomechanical Phenomena; D003094:Collagen / Q000737:chemistry*; D055119:Elastic Modulus; D004549:Elastin / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D005109:Extracellular Matrix / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism; D013718:Tensile Strength; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D011994:Recombinant Proteins; D003094:Collagen; D004549:Elastin
keywords: bio-MEMS; collagen microfibers; elastin-mimetic protein polymer; fiber reinforced composite
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