Improvements in microstructural, mechanical, and biocompatibility properties of nano-sized hydroxyapatites doped with yttrium and fluoride

Hydroxyapatite was doped with Y3+ (2.5, 5 and 7.5 mol%) and F (2.5 mol%) ions (2.5YFHA, 5YFHA, 7.5YFHA, respectively) to compare its structural and mechanical properties and cellular response with pure-hydroxyapatite. No second phases were observed by X-ray diffraction spectra of 2.5YFHA. Doped hydroxyapatites had F- bonds in addition to OH- bonds. Hydroxyapatites sintered at 900 and 1100 degrees C were in nano-size. 7.5YFHA sintered at 1300 degrees C had the highest microhardness value. 2.5YFHA sintered at 1100 degrees C had the highest fracture toughness value. MTT viability assays showed high cell attachments on 2.5YFHA. Cell proliferation on 2.5YFHA and 5YFHA sintered at 1100 and 1300 degrees C was comparable with the control after 5-day culture. The highest ALP production and calcium deposition were observed on all hydroxyapatites sintered at 1100 degrees C. 2.5YFHA sintered at 1100 degrees C can be an alternative for hydroxyapatite in orthopedic applications. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.