Biomedical Engineering Reference
In-Depth Information
functionalized with inorganic regions). If the presence of soluble calcium
and a silica component are important for Bioglass and Bioverit for bone
bonding and osteogenic stimulation, organic materials having either
Si-O bonds or Ca as their ingredients might not only exhibit good
cytocompatibility but also stimulate similar reactions in the body's
environment to form strong bonds with bone tissue. The hybridization
not only yields flexible and bioactive materials but also causes diverse
effects favorable to biomedical applications. The Si-O bonds provide
a tough inorganic siloxane skeleton like that of silicone as the result
of self-condensation among
>
Si-OH groups (the symbol
>
stands for
additional bonds).
10.3 SELF-ASSEMBLED HYBRID FILMS AND LAYERS
OF GRAFTED SILANES
Another type of hybrid is materials that are given new functionality
by adding molecules to the surfaces of inorganics (Figure 10.3), for
example, nanoparticles. The added functionality could be used to attach
specific proteins or growth factors to an implant surface or to guide
nanoparticles toward specific locations, for example, tumor targeting.
Particularly, complex porous particles can contain drugs and have
surface functional groups that direct them toward tumors (rather than
other cells) so that they release their payload in the right place.
NH 2
C
-Si-
SiO 2
O
Si
^
Figure 10.3 Schematic of a silica surface functionalized with aminosilanes. The
-NH 2 groups protruding from the surface of the material change the functionality
of the surface and could be used for attaching drugs or growth factors.
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