Nucleation bone-like apatite

Poly(oxyethylene)-Si02 ormosils have been prepared as an approach to the preparation of biologically active polymer-apatite composites. For this purpose, Yamamoto et al. [72] obtained these Class II hybrids from triethoxysilyl-terminated poly(oxyethylene) (PEG) and TEOS by using the in situ sol-gel process. After being subjected to the biomimetic process to form the bone-like apatite layer, it was found that a dense apatite layer could be prepared on the hybrid materials, indicating that the silanol groups provide effective sites for CHA nucleation and growth. 

Self-assembled monolayers terminated with COOH and H2PO4 groups, form bone-like apatite on their surfaces in an SBF [34]. This means that COOH and H2PO4 groups are also effective for apatite nucleation. These functional... 

The COOH group is also effective for apatite nucleation, as described in Section 14.1.6. Alginic acid possesses the COOH group in its structure, as shown in Figure 14.1.22. Therefore, its fibres form bone-like apatite on its surface in an SBF within 7 days, when they are previously treated in an aqueous saturated Ca(OH)2 solution, as shown in Figure 14.1.22 (Kokubo, unpublished). Chitin fibres can be modified to form COOH groups on their surfaces by car-boxymethylation. They also form apatite on their surfaces in an SBF within 7 days, when they are previously treated in an aqueous saturated Ca(OH)2 solution [63]. 

Metastable synthetic (or modified) simulated body fluids (SBFs), with an inorganic salt composition similar to that of human blood plasma, incubate and faciUtate the spontaneous nucleation and growth of nanosized, carbonated and bone-like apatite at physiological pH and temperature. SBFs were first used by Kokubo andTakadama (52) in biomimetic synthesis to prove the similarity between the in vitro and in vivo behaviors of certain glass-ceramic compositions. Some typical SBF compositions are listed in Table 12.1. In these studies, the glass-ceramic samples were soaked in SBF solutions and their surfaces coated with a poorly crystallized calcium-deficient and carbonatebone apatite. A metastable SBF has been proven to incubate and facilitate the... 

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