Chitosan-nHA composite scaffolds

Remarkable research has been conducted on chitosan-nHA (Fig. 7.1(b)) in past decades. However, still more advanced investigative research is needed to design a 

Reproduced the figure with permission from Elsevier. (Chen et al., 2002) 

whereas chitosan with nHA was prepared with an in situ hybridization method. The highest degree of bone regeneration potential observed in nHA powder, with the bone regeneration lowest in nHA with 6g of chitosan (Tavakol et al., 2013). 

Chitosan with nHA macrosphere has also been prepared using a water-in-oil emulsion by in situ generation method. The availability of nHA in the microsphere is poorly crystalline in nature, similar to biological apatite (Ding et al., 2012). Electrospun scaffolds of chitosan and nHA composite were prepared using SBF solution (Thien et al., 

Particle size of HA plays an important role in bone regeneration. The additions of nano HA and micro HA in the chitosan matrix were developed with freeze dry lyo-philization method. Lee et al. reported on the effects of the surface characteristics of nHA and micro-HA films on the behavior of human mesenchymal stem cells (hMSCs) in vitro. The cell proliferation of hMSC in chitosan with nHA shows better performance than micro-HA with chitosan due to higher surface area of nHA (Lee et al., 2011). The tensile modulus increases more for composites containing nHA than composites containing micro-HA due to nHA being uniformly distributed in the matrix 

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Saravanan et al. (2011) have suggested that addition of nanosilver (nAg) to the chitosan-nHA composite scaffold significantly improved antimicrobial properties those composite scaffolds, which are nontoxic to rat osteoprogenitor cells and human osteosarcoma cell line, were prepared by the freeze-dry method. Zinc has been proven to have an antimicrobial property the addition of nanozinc in nHA to chitosan showed better performance toward bone-tissue engineering (Tripathi et al., 2012). Chen et al. reported two methods for the preparation of chitosan-nHA, the in situ and sol-gel methods. In situ additions of HA possess better performance in elastic modulus, compressive strength, cell proliferation and alkaline phosphatase activity. This may be because, uniformly dispersed and chemical interaction may be possible in in situ formation of HA in the chitosan matrix (Chen et al., 2011). 

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