dispersed solutions of microscaled HAp powder and CTS at various concentrations.
These films can contain up to 70% HAp without microcracks, phase separation, or
brittleness. The HAp powders were well dispersed in the film without clustering or
aggregation. These observations were explained by the presence of CTS, which
retains the physico-mechanical properties of the film and captures the HAp powders
in the matrix. It is anticipated that these films will be potentially useful for the direct
or indirect delivery of HAp materials in localized areas of osteoporosis via a patch on
skin or bone. Hybrid CTS/HAp composite materials were also developed by Araujo
et al. [145]. The effects of the concentration of a crosslinking agent (genipin),
concentration of lactic acid, and presence of HAp powder on the evolution of
rheological properties have been studied. It was found that the concentration of
lactic acid has a marginal influence on the rheological properties, affecting mostly
the final microstructure. The pore size of composites decreases with increasing
concentration of lactic acid. The microstructure of CTS scaffolds generally consists
of large and interconnected pores, the size of which also tends to decrease with
increasing amounts of genipin. Moreover, the CTS and CTS/HAp scaffolds
exhibited an excellent bioactivity in vitro in the presence of SBF, showing the
formation of an apatitic layer, even in the early stages of immersion.
7 Conclusions
Nature has set a high standard for the scientists and engineers who design bone
grafts to assist in the repair or regeneration of the functions of defective bone tissues
into normal healthy tissues. In this regard, the most preferable goal is to design and
produce bone grafts that mimic all the functional physical, mechanical, chemical,
and biological properties of natural bone. In this chapter, a detailed account of the
structure of natural bone and the different types of bone grafting strategies are
described. Recently, polymer/HAp-based nanocomposite materials have received
much attention in biomimetic bone grafting because the interfacial adhesion
between organic polymers and inorganic nanoHAp is good and also the dispersion
of HAp is uniform at the nanolevel. NanoHAp also provides a large surface area and
surface reactivity and thus the composites are compositionally and structurally
similar to host bone and able to promote bone-related cellular functions extensively. A number of methods have been reported and presented in this chapter for
bone grafting using nanoHAp organic polymers. Among several organic polymers,
the use of nonbiodegradable and biodegradable CTS/nanoHAp has been described
in detail. However, no synthetic graft is yet able to match the performance of
natural bone tissue, even with the advances in science and technology. It is believed
that a combination of osteoconductive matrix with osteogenic cells and
osteoinductive growth factors creates an ideal bone graft. However, the design of
bone grafts is still at the laboratory research level, and thus development of
novel bone grafting techniques is highly desirable and is a big task for scientists.
160
A. Bhowmick et al.
These films can contain up to 70% HAp without microcracks, phase separation, or
brittleness. The HAp powders were well dispersed in the film without clustering or
aggregation. These observations were explained by the presence of CTS, which
retains the physico-mechanical properties of the film and captures the HAp powders
in the matrix. It is anticipated that these films will be potentially useful for the direct
or indirect delivery of HAp materials in localized areas of osteoporosis via a patch on
skin or bone. Hybrid CTS/HAp composite materials were also developed by Araujo
et al. [145]. The effects of the concentration of a crosslinking agent (genipin),
concentration of lactic acid, and presence of HAp powder on the evolution of
rheological properties have been studied. It was found that the concentration of
lactic acid has a marginal influence on the rheological properties, affecting mostly
the final microstructure. The pore size of composites decreases with increasing
concentration of lactic acid. The microstructure of CTS scaffolds generally consists
of large and interconnected pores, the size of which also tends to decrease with
increasing amounts of genipin. Moreover, the CTS and CTS/HAp scaffolds
exhibited an excellent bioactivity in vitro in the presence of SBF, showing the
formation of an apatitic layer, even in the early stages of immersion.
7 Conclusions
Nature has set a high standard for the scientists and engineers who design bone
grafts to assist in the repair or regeneration of the functions of defective bone tissues
into normal healthy tissues. In this regard, the most preferable goal is to design and
produce bone grafts that mimic all the functional physical, mechanical, chemical,
and biological properties of natural bone. In this chapter, a detailed account of the
structure of natural bone and the different types of bone grafting strategies are
described. Recently, polymer/HAp-based nanocomposite materials have received
much attention in biomimetic bone grafting because the interfacial adhesion
between organic polymers and inorganic nanoHAp is good and also the dispersion
of HAp is uniform at the nanolevel. NanoHAp also provides a large surface area and
surface reactivity and thus the composites are compositionally and structurally
similar to host bone and able to promote bone-related cellular functions extensively. A number of methods have been reported and presented in this chapter for
bone grafting using nanoHAp organic polymers. Among several organic polymers,
the use of nonbiodegradable and biodegradable CTS/nanoHAp has been described
in detail. However, no synthetic graft is yet able to match the performance of
natural bone tissue, even with the advances in science and technology. It is believed
that a combination of osteoconductive matrix with osteogenic cells and
osteoinductive growth factors creates an ideal bone graft. However, the design of
bone grafts is still at the laboratory research level, and thus development of
novel bone grafting techniques is highly desirable and is a big task for scientists.
160
A. Bhowmick et al.