Biomedical Engineering Reference
In-Depth Information
perturbation due to nHA particles, however, was small even in proportions
of up to 50% due to their nanometer scale and uniform distribution. The
SEM images showed that the nHA particles were dispersed in the pore walls
of the scaffolds and bound to the polymer very well. PLLA/nHA scaffolds
prepared using a pure solvent system had a regular anisotropic but open 3D
pore structure similar to neat polymer scaffolds, whereas PLLA/mHA
scaffolds had an isotropic irregular pore structure.
TiO
2
nanoparticles (nTiO
2
) have recently been proposed as attractive
fillers for biodegradable PDLLA matrices (Boccaccini et al., 2006). 3D
PDLLA foams containing both nTiO
2
and Bioglass
â
additions have been
synthesized by TIPS. The foams demonstrated enhancement of bioactivity
and surface nanotopography.
17.4.3 Electrospinning
The electrospinning technique has attracted great interest because it allows
the production of fibrous non-woven micro/nano fabrics for tissue
engineering, mainly due to structural similarity to the tissue extracellular
matrix (ECM) (Bianco et al., 2009; Greiner and Wendorff, 2007). The
composition and topology of the ECM was found to affect cell morphology,
function and physiological response (Causa et al., 2007). Electrospun
nanofibrous scaffolds, which aim to mimic the architecture and biological
functions of ECM, are considered very promising substrates for tissue
engineering. PCL scaffolds, a bioresorbable aliphatic polyester, have been
used to provide a 3D environment for in-vitro embryonic stem cell cultures.
Electrospun nanocomposite scaffolds based on bioresorbable polymers and
conventional HA allow osteoblast proliferation and differentiation, and are
thus considered very promising as bone scaffolding materials (Bianco et al.,
2009).
Fibrous PCL/Ca-deficient nHA nanocomposites were obtained by
electrospinning. The electrospun mats showed a non-woven architecture,
with average fiber size of 1.5
m, porosity of 80-90% and specific surface
area of 16 m
2
/g (Fig. 17.7). Murine embryonic stem (ES) cell response to
neat PCL and to PCL/Ca-deficient nHA (6.4 wt%) mats was evaluated by
analyzing morphological, metabolic and functional markers. Cells growing
on either scaffold proliferated and maintained pluripotency markers at
essentially the same rate as cells growing on standard tissue culture plates
with no detectable signs of cytotoxicity, despite a lower cell adhesion at the
beginning of culture. These results indicate that electrospun PCL scaffolds
may provide adequate supports for murine ES cell proliferation in a
pluripotent state, and that the presence of Ca-deficient nHA within the mat
does not interfere with their growth.
Aligned nanocomposite fibers of PLGA/nHA were fabricated using a
μ
