Bioactive Polymers and Nanobiomaterials Composites for Bone Tissue Engineering - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 91

to restore with time, provide structural support while enhancing bone tissue
formation, and be easy to use clinically and cost-effective [11]. Additionally,
the materials should be shapeable, or polymerizable in situ to ensure good
integration in the defective area [2]. Tissue engineering scaffolds should
facilitate the colonization of cells and possess properties and characteris-
tics that enhance cell attachment, proliferation, migration and expression
of native phenotypes. The physical properties of scaffold such as porosity,
the surface-area-to-volume ratio, pore size, pore interconnectivity, mechani-
cal strength and overall geometry are all critically important factors in the
design and fabrication of materials for bone tissue engineering [10, 12].
The search for innovative biomaterials is an iterative process for the
development of a new therapeutic concept and now encompasses nanoma-
terials and their composites, particularly, polymers and nanocomposites.
Because of high surface area, the nanomaterials have a high level of interac-
tion with the lowest hierarchical levels, thereby enhancing their bioactivity.
Such nanocomposites comprising a polymer matrix and bioactive micro/
nanofi llers constitute specifi c biomaterials for internal bone implants with
biological and mechanical properties tailored for a given medical use.
This chapter focuses on the recent advancement in bioactive polymers
and nanobiomaterial composites, the fabrication of 3D biomimetic scaf-
folds for bone tissue engineering, particularly in the study of polymer and
non-metallic-based nanocomposites, both in in vitro and in vivo bone tis-
sue regeneration. Additionally, this chapter discusses the structure and
properties of the polymer-nanocomposites scaffolds.

5.2 Design and Fabrication of Biomimetic 3D

Polymer-Nanocomposites Scaffolds

A variety of designs and processing and fabrication methods of 3D bone
tissue engineering based on polymer-nanocompsites scaffolds have been
developed. Each method has its advantages and disadvantages. The strate-
gies of incorporation of bionanomaterials into polymer matrices to enhance
structural, mechanical and biological properties are presented in Figure 5.1.
The structure of the scaffold should act as a template for 3D tissue growth,
which should ideally consist of a highly porous interconnected network
with interconnected pores 100 μm

[13, 14]. High porosity, normally between 60% and 80% is required to
accommodate osteoblasts or osteoprogenitor cells, which, in turn, allows
cell proliferation and differentiation to enhance bone tissue formation.
High interconnectivities between pores are also desirable for uniform cell
seeding and distribution to facilitate the diffusion of nutrients into and dif-
fusion of metabolites out of cell or scaffold constructs. The scaffold should
have adequate mechanical stability to provide a suitable environment for

> 50 μm in diameter and pore diameters >