Biomedical Engineering Reference
In-Depth Information
and inally be affected by sterilization. Till now, there are no known
materials which totally satisfy these criteria so when a foreign
material is placed into a biological environment, inevitable reactions
occurs which are detrimental to both the host and the material.
The surface properties of biomaterials are associated with cell
adhesion and subsequent various cell behaviors, such as proliferation,
migration, cytoskeletal arrangement, differentiation, and apoptosis
[12, 99]. In particular, a large number of studies on cell adhesion to
various substrate surfaces have been conducted. Cell adhesion and
its performance have been reported to depend on the characteristics
of substrates, including the chemical composition, surface charge,
water wettability, roughness, and size of the cytophilic area
[5, 23, 44, 62, 63, 67, 68, 90, 104, 106, 107, 133, 135, 138, 141−143].
Understanding the mechanisms whereby cells sense and respond to
chemical, physical and biological signals from material surfaces will
facilitate the development of novel biomaterials for the control of
cell behavior.
All implantable materials possess inherent morphological,
chemical, and electrical surface qualities which elicit reactionary
responses from the surrounding biological environment. In
fact, biocompatibility can be described as multifactorial in that
simultaneous stimuli from any of these material properties can
affect the host response.
Using nanotechnology for regenerative medicine becomes
obvious when examining nature [153]. Bone is a nanocomposite
that consists of a protein based soft hydrogel template (i.e., collagen,
non-collagenous proteins (laminin, ibronectin, vitronectin), and
water) and hard inorganic components (hydroxyapatite, HA,
Ca
10
(PO
4
)
6
(OH)
2
) [139, 154]. Speciically, 70% of the bone matrix is
composed of nanocrystalline HA [57].
In addition to the dimensional similarity to bone/cartilage
tissue, nanomaterials also exhibit unique surface properties (such
as surface topography, surface chemistry, surface wettability, and
surface energy) due to their signiicantly increased surface area and
roughness compared to conventional or micron structured materials.
As known, material surface properties mediate speciic protein (such
as ibronectin, vitronectin, and laminin) adsorption and bioactivity
before cells adhere on implants, further regulating cell behavior
and dictating tissue regeneration [139]. Furthermore, an important
criterion for designing medical implant materials is the formation
