title: Bioactive surface modification of hydroxyapatite.
abstract: The purpose of this study was to establish an acid-etching procedure for altering the Ca/P ratio of the nanostructured surface of hydroxyapatite (HAP) by using surface chemical and morphological analyses (XPS, XRD, SEM, surface roughness, and wettability) and to evaluate the in vitro response of osteoblast-like cells (MC3T3-E1 cells) to the modified surfaces. This study utilized HAP and HAP treated with 10%, 20%, 30%, 40%, 50%, or 60% phosphoric acid solution for 10 minutes at 25°C, followed by rinsing 3 times with ultrapure water. The 30% phosphoric acid etching process that provided a Ca/P ratio of 1.50, without destruction of the grain boundary of HAP, was selected as a surface-modification procedure. Additionally, HAP treated by the 30% phosphoric acid etching process was stored under dry conditions at 25°C for 12 hours, and the Ca/P ratio approximated to 1.00 accidentally. The initial adhesion, proliferation, and differentiation (alkaline phosphatase (ALP) activity and relative mRNA level for ALP) of MC3T3-E1 cells on the modified surfaces were significantly promoted (P < 0.05 and 0.01). These findings show that the 30% phosphoric acid etching process for the nanostructured HAP surface can alter the Ca/P ratio effectively and may accelerate the initial adhesion, proliferation, and differentiation of MC3T3-E1 cells.
authors.affiliation: Department of Advanced Prosthodontics, Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Minami-ku, Hiroshima, Japan. abey@hiroshima-u.ac.jp
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Abe
authors.forename: Yohei
authors.initials: Y
authors.lastname: Okazaki
authors.forename: Kyou
authors.initials: K
authors.lastname: Hiasa
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yasuda
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nogami
authors.forename: Wataru
authors.initials: W
authors.lastname: Mizumachi
authors.forename: Isao
authors.initials: I
authors.lastname: Hirata
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D017886:Durapatite / Q000494:pharmacology*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D056951:Photoelectron Spectroscopy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics; D017155:Wettability / Q000187:drug effects*; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D012333:RNA, Messenger; D017886:Durapatite; D000469:Alkaline Phosphatase