Systematic Silk Hydrogel Microfiber Design: Platform for Meticulous Fibrous Biomaterial Scaffolds.
Bradner, Sarah.
2019
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Collagen fibrils are
the fundamental unit of complex native tissue that assemble for multiscale
structure-function properties. Characteristic non-linear tissue response is afforded to
native tissue through extrafibrillar interactions add plasticity to stiff units for
energy dissipation between stiff-soft interfaces. In bone, mineral crystals serve as an
additional dissipative interface that ... read morerenders stiff-soft transitions between
mineral-collagen boundaries. Fiber units play an essential role for acute material
responses for fracture resistance, but also provide hierarchical biochemical cues for
localized cell response for tissue maintenance. We develop a microfiber platform to
serve as fundamental units of fibrous scaffold design through adaptation of silk fibroin
protein. Silk overcomes mechanical limitations of reconstituted collagen materials and
can be processed into a versatile range of formats. Here, we utilize enzymatic
cross-linking to fabricate a silk hydrogel microfiber platform to investigate as a fiber
unit for future fibrous material design. The silk hydrogel microfiber is structurally
and mechanically characterized as a singular unit to assess fabrication and
post-processing techniques on fibril arrangements as a function of strain. The fiber
unit is then functionalized through the incorporation of a model glycoprotein, bovine
serum albumin (BSA), and a biosilica precursor peptide, R5, to add a biomimetic
fiber-matrix response with strain. To assess ion presence on material response,
quasi-static tensile tests were performed in calcium DI water baths at physiological
concentration. We propose that silk provides mechanical and structural nanofibrous
template that models native collagen. When combined as a biomimetic hybrid with BSA, we
achieve improved structural and thus, mechanical fiber properties. Though multiscale
energy dissipation from protein-protein and protein-water interactions, fiber matrices
are stabilized for short and long-range rearrangements with strain with controlled
structural order prior to material failure. Incorporation of R5 peptide reveals
strain-driven biomineralization along the fiber axis and within the porous
ultrastructure for potential mineralized fibrous materials. This microfiber platform has
potential for broader material design and provides a meticulous approach for
architecture fibril materials; functionalization provides broader implications
stretching outside of tissue engineering such as conductive materials such as optics,
robotics, and drug delivery.
Thesis (Ph.D.)--Tufts University, 2019.
Submitted to the Dept. of Biomedical Engineering.
Advisor: David Kaplan.
Committee: Fiorenzo Omenetto, Peggy Cebe, and Gulden Camci-Unal.
Keyword: Biomedical engineering.read less - ID:
- fb494n58t
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