On Biomimetics
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sub-micron and even smaller scales are the results of human body’s biological and chemical
processing, and we don’t need and also cannot fabricate them. The artificial scaffold acts
only as temporary ECM, and will be resorbed and remodeled by biological and chemical
processes of human body to achieve completely natural bone tissue at the end of the
recovery. Since the high mechanical strength requirement for artificial cortical bone is
difficult to reach from most biomaterials, our target tissue in this research will be the highly
porous lower-strength trabecular bone.Fig. 1. Basic architecture of bone [Rho et al., 1998].Since the porosity of the bone scaffold is very important, many manufacturing techniques
and biomaterials were used to control the pore size and porosity rate. New biocompatible
materials and a number of fabrication technologies have been explored and developed to
create synthetic bone grafts, which process biodegradable and biocompatible materials into
a 3-D scaffold with high porosity and surface area [Hutmacher, 2000]. These technologies
include Porogen Leaching, Fiber Bonding, Gas Foaming, Gel Casting, Solution Casting and
Emulsion Freeze-Drying [Gadzag et al., 1995; Chapekar, 2000; Mikos, Bao, Cima, Ingber and
Vacanti, 1993; Harris, Kim and Mooney, 1998; Coombes and Heckman, 1992; Singhal,
Agrawal and Athannasiou, 1996 and Mooney, Baldwin, Suh, Vacanti and Langer, 1996]. In
the above mentioned methods, although researchers have achieved significant progresses in
making a porous scaffold for bone tissue engineering, many difficulties remain. Most of the
above-mentioned methods for fabricating 3D scaffolds are mainly used for laboratory
testing purpose and are not practical production process, placing substantial limitations on
manufacturing. Consequently, the control of scaffold architecture, such as pore size, shape,
porosity, and interconnectivity is hard to reach, thus using these fabrication techniques is
still highly process driven, not design driven [Lee, Ryu, Lee, Hong, Chang and Lee, 2005].
And most of the above-mentioned processes involve organic solvent or high temperature