Advances in Synthesis and Functional Modification of Nanohydroxyapatite

Table 1

Difference between natural bone and synthetic nanoapatite.

	Morphology	Dimension	Calcium phosphate ratio	Crystallinity	Representative method
Natural bone	Needle	5–10 nm	1.50	low
	Flaky	20–50 nm
Chemical synthesis	Needle	130–170 nm	1.640–1.643	high	Hydrothermal
		15–25 nm			Coprecipitation
Organic polymer template synthesis	Needle	70–90 nm	1.35	low	Polyamide
		10–20 nm			Polyacrylic acid
		2–5 nm			Polyethylene glycol
	Spherical	30–50 nm			Polyethyleneimine
		1–5 µm
Biological template synthesis	Flaky	7–8 nm	1.5–1.66	low	Collagen
	Fusiform	30–40 nm			Chitosan
	Flaky	6 nm			Chondroitin sulfate
		12 nm