Biomedical Engineering Reference
In-Depth Information
Furthermore, BCP (HA + β-TCP)/agarose macroporous scaffolds
with controlled and complete interconnection, high porosity,
thoroughly open pores and tailored pore size were prepared for
tissue engineering application [857, 858]. Agarose, a biodegradable
polymer, was selected as the organic matrix because it was a
biocompatible hydrogel, which acted as gelling agent leading to strong
gels and fast room temperature polymerization. Porous scaffolds
with the designed architecture were manufactured by combining
a low temperature shaping method with stereo-lithography and
two drying techniques. The biocompatibility of this BCP/agarose
system was tested with mouse L929 fibroblast and human SAOS-2
osteoblast during different colonization times [859].
Fibrin sealants are non-cytotoxic, fully resorbable, biological
matrices that simulate the last stages of a natural coagulation
cascade, forming a structured fibrin clot similar to a physiological
clot [860]. Biocomposites of calcium orthophosphates with fibrin
sealants might develop the clinical applications of bone substitutes.
The 3D mesh of fibrin sealant interpenetrates the macro- and
micro-porous structure of calcium orthophosphate ceramics
[11]. The physical, chemical, and biological properties of calcium
orthophosphate bioceramics and the fibrin glue might be cumulated
in biocomposites, suitable for preparation of advanced bone grafts
[861-873].
Furthermore,therearebiocompositesofcalciumorthophosphates
with bisphosphonates [874], silk fibroin (that is a hard protein
extracted from silk cocoon) [312, 670-672, 677, 678, 875-881],
chitosan + silk fibroin [882], fibronectin [883], chondroitin sulfate
[299, 733, 884], casein phosphopeptides [885], and vitamins [886].
Besides, the reader's attention is pointed out to an interesting
approach to crystallize CDHA inside poly(allylamine)/poly(styrene
sulfonate) polyelectrolyte capsules resulting in empty biocomposite
spheres of micron size [887]. Depending on the amount of precipitated
CDHA, the thickness of the shell of biocomposite spheres can be
varied between 25 and 150 nm. These biocomposite capsules might
find application as medical agents for bone repairing and catalytic
microreactors [887].
6.4.6
Injectable Bone Substitutes (IBS)
With the development of minimally invasive surgical methods, for
example percutaneous surgery, directly injectable biomaterials are
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