A novel thermolysis method of colloidal protein precursors to prepare hydroxyapatite nanocrystals

A novel thermolysis method of colloidal protein precursors is introduced to prepare hydroxyapatite (HAP) nanocrystals. The colloidal protein precursors are sonochemically synthesized from saturated Ca(OH)(2) aqueous solution, Ca(H2PO4)(2) aqueous solution and bovine serum albumin (BSA) molecules. The colloidal protein precursors are amorphous and composed of 15-90 nm near spherical calcium phosphate natioparticles and BSA molecules. The particle size analysis shows the volume particle size distribution is from 9.0 nm to 222.6 nm and the volume-averaged particle size is 45.8 rim. During the calcination procedure BSA molecules are burningly removed and the HAP nanocrystals can be obtained at 500 degrees C. The effects of BSA concentration on the properties of samples are discussed. Results show that BSA combustion can promote the transformation of crystalline HAP from amorphous material. Moreover, the increase of BSA concentration reduces the crystalline sizes of HAP crystals and the crystallinity of product. With BSA concentration of 5 g/L, the obtained HAP nanocrystals are mainly 25 similar to 100 nm similar spherical nanoparticles besides some 40 similar to 70 nmx75 similar to 150 nm short rod-like crystals. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim