Effect of anionic PAMAM with amido groups starburst dendrimers on the crystallization of Ca10(PO4)6(OH)2 by hydrothermal method

Synthesis of hydroxyapatite (HAP; Ca10(PO4)6(OH)2) nanoparticles with ellipsoid-like morphology and different size was achieved by hydrothermal crystallization at 150 °C and pH 9 through a mixture solution of Ca(NO3)2 and (NH4)2HPO4 in the presence of the PAMAM with amido groups at the external surface. As the generation number of the PAMAM dendrimer with amido groups at the external surface increased from G1.0 to G4.0, the particle sizes of hydroxyapatite were decreased from 82, 77, 48 to 38 nm, respectively, and while the shape of hydroxyapatite also were changed from rod- to ellipsoid-like. With further increase in the generation number to G5.0, the particle size was not changed. The relationship between concentration of the dendrimer and the particle size in G4.0 of the PAMAM dendrimer with amido groups was also studied under the same condition. As concentration increased from 5.0 to 40 g l−1, the particle sizes of ellipsoid-like were reduced from 55 to 25 nm.