Bioactive Polymers and Nanobiomaterials Composites for Bone Tissue Engineering - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 98

with the human body and is considered to be a useful polymer for bio-
medical applications. PA-6,6 displays some structural similarity to col-
lagen, and the depolymerization products (hexamethylenediamine and
hexanedioic acid) act in vivo as antibacterial agents [43]. However PA-6,6
lacks the ability for specifi c interactions with bone tissue. Therefore, it is
compensated by preparation of PA-composites with HAp nanoparticles
additives to enhance bioactivity [43] with the prospect of being an effec-
tive bone replacement material. It has been reported in a separate study,
that polyamide (PA 8063) and nanoHAp can be used to prepare bone-
like composites with high HAp content and with good homogeneity and
chemical interface bonding [44]. Additionally, it can be comparable with
natural bone; the synthetic nanocomposites had been found to give bone-
like structure almost similar to that of human. The nanoHAp provides
the bioactivity for the composite through interactions with natural bone,
and PA is responsible for mechanical strength and toughness. Therefore,
PA/HAp nanocomposites could be one of the better groups of bioactive
materials for load-bearing bone repair or substitution [44]. The solution
method can be used to prepare PA-6/nanoapatite (NA) biocomposites
[45] with uniform distribution in the PA-6 matrix. Authors also reported
that a molecular level of interactions exists between nanoparticles and
PA-6, which eventually improves the mechanical properties of the com-
posites. This will be similar to natural bone architecture with intercon-
nected porous network having porosity of 80% and mean pore size of
~ 300 μm, and at the same time providing good biocompatibility. The com-
posite prepared with 65% NA content with 35% PA showed high mechani-
cal strength close to the natural bone [45]. The scaffolds were fabricated
by the “injecting foam method” with interconnected pores having ~ 80%
porosity and mean pore size of ~ 300 μm. When implanted into cortical
bone, the composite combined directly with the natural bone without
fi brous capsule tissue between implant and host bone.

5.3.3 Poly(ether ether ketone) (PEEK) Nanocomposites

PEEK is a polyaromatic, semicrystalline, rigid, thermoplastic polymer with
high mechanical properties, and resistence to chemicals, radiation and
temperature. It also offers ease of processing. Besides, PEEK is non-cytotoxic
and can be repeatedly sterilized using conventional steam, g -irradiation
and ethylene oxide treatment without deterioration of its mechanical
properties. All these benefi ts have rendered particulate-reinforced PEEK
attractive for structural support material for orthopaedic implants [46].
PEEK is a bioinert polymer, and the addition of ceramic-based nanoparti-
cles such as HAp in the PEEK matrix enhance biocompatibility and natural
bone formation and mechanical properties in the region of cortical bone,
making it a potential candidate for use in load-bearing applications [47].