Date of Completion

4-4-2014

Embargo Period

4-3-2015

Keywords

collagen, apatite, coating, scaffold, bone, tissue engineering

Major Advisor

Mei Wei

Associate Advisor

Bryan D Huey

Associate Advisor

Yu Lei

Field of Study

Materials Science

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Natural bone has a complex hierarchical structure in which well-organized collagen fibrils are reinforced by apatite nano crystals. Inspired by bone, biomimetic collagen-apatite (Col-Ap) materials such as Col-Ap composite coatings and 3-D porous Col-Ap scaffold have been developed to enhance osteointegration between implant and host bone and facilitate bone repair and regeneration, respectively.

First, a bioactive Col-Ap composite coating was created on Ti6Al4V surface using a collagen-containing modified simulated body fluid (m-SBF). The coating achieved was a composite of bone-like carbonated apatite and collagen type I. The coating composition and morphology could be tailored by carefully adjusting the collagen concentration in m-SBF. In vitro cell culture study shows that addition of collagen promotes osteoblast activities, which may lead to early bone formation.

Second, biomimetic Col-Ap composite scaffold was prepared using freeze-drying technique. The scaffolds created have tunable structures and compositions suitable for different tissue repair and regeneration applications. The scaffolds are comprised of hierarchically organized collagen fibers and poorly crystalline apatite nanoparticles mimicking the microstructure of natural bone. At the macrostructure level, the Col-Ap scaffolds with either an isotropic equiaxed structure or a unidirectional lamellar structure have been successfully prepared by controllable freeze casting. The pore size of both scaffold types can be easily adjusted.

Third, a unique multi-level lamellar scaffold consisting of co-aligned micro- and macro- pores has been developed by freeze-drying a mineralized collagen hydrogel. The scaffold preserves the interconnected network-structure of the hydrogel and superior tensile properties of the collagen fibers. This group of novel scaffolds has been found to have bone-like morphology, adjustable structure, improved mechanical strength and good biocompatibility.

In summary, a methodology has been successfully developed for preparation of biomimetic composites with both micro- and macro- structures precisely controlled to meet different requirements in bone tissue engineering applications.

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