start-ver=1.4 cd-journal=joma no-vol=134 cd-vols= no-issue=1 article-no= start-page=31 end-page=37 dt-received= dt-revised= dt-accepted= dt-pub-year=2026 dt-pub=20260101 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Structure and acid resistance of fluoride-treated hydroxyapatite particles en-subtitle= kn-subtitle= en-abstract= kn-abstract=Topical fluoride is used in clinical dentistry to prevent dental caries. The primary reaction product formed on the tooth surface after topical fluoride application is calcium fluoride (CaF2). In this study, we investigated the effect of deposited CaF2 on the acid resistance of fluoride-treated hydroxyapatite (HAp). Commercial HAp particles were treated with two types of fluoride-containing acetic acid-sodium acetate (Ac-AcNa) buffer solutions, with and without the addition of phosphate ions. X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) analyses confirmed the formation of fluorine-substituted hydroxyapatite (F-HAp), along with a hydration layer containing calcium phosphate and CaF2. Phase composition analysis revealed that the presence of phosphate ions in the fluoride treatment solution reduced the amount of CaF2 deposited. Acid resistance evaluation and phase composition analysis indicated that the initial dissolution rate of the fluoride-treated HAp in Ac-AcNa buffer solutions decreased on surfaces densely covered with CaF2 particles. en-copyright= kn-copyright= en-aut-name=HayakawaSatoshi en-aut-sei=Hayakawa en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=AndoKazuki en-aut-sei=Ando en-aut-mei=Kazuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=3 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Hydroxyapatite kn-keyword=Hydroxyapatite en-keyword=Fluoride treatment kn-keyword=Fluoride treatment en-keyword=Calcium fluoride kn-keyword=Calcium fluoride en-keyword=Acid resistance kn-keyword=Acid resistance END start-ver=1.4 cd-journal=joma no-vol=134 cd-vols= no-issue=1 article-no= start-page=24 end-page=30 dt-received= dt-revised= dt-accepted= dt-pub-year=2026 dt-pub=20260101 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Preparation of brookite-type titanium dioxide particle layer on titanium surfaces via hydrothermal treatment and evaluation of in vitro apatite-forming ability en-subtitle= kn-subtitle= en-abstract= kn-abstract=In this study, we prepared a brookite-type titanium dioxide particle layer on the surface of titanium substrates via hydrothermal treatment in aqueous urea solutions containing sodium chloride (NaCl) and examined its in vitro apatite-forming ability. Increasing the urea concentration suppressed the formation of anatase-type titanium dioxide on the titanium substrate, forming a particle layer composed of pure brookite-type titanium dioxide. The size and packing density of brookite-type titanium dioxide particles formed on the titanium substrate increased with the NaCl concentration in a 7.0 mol·dm−3 urea solution. When titanium substrates hydrothermally treated in aqueous solutions of 7.0 mol·dm−3 urea and 2.0 mol·dm−3 NaCl were soaked in a simulated body fluid for various periods up to 7 d, the substrate surface was densely covered with hemispherical apatite particles (5.3 µm in diameter) within 3 d, indicating that the brookite-type titanium dioxide particle layer had an excellent apatite-forming ability comparable to that of the anatase-type titanium dioxide particle layer. en-copyright= kn-copyright= en-aut-name=HayakawaSatoshi en-aut-sei=Hayakawa en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=NakamotoYushi en-aut-sei=Nakamoto en-aut-mei=Yushi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KojimaSeiya en-aut-sei=Kojima en-aut-mei=Seiya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NagaokaNoriyuki en-aut-sei=Nagaoka en-aut-mei=Noriyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=KataokaTakuya en-aut-sei=Kataoka en-aut-mei=Takuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=4 en-affil=Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School kn-affil= affil-num=5 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=6 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Brookite-type titanium dioxide kn-keyword=Brookite-type titanium dioxide en-keyword=Hydrothermal treatment kn-keyword=Hydrothermal treatment en-keyword=Urea kn-keyword=Urea en-keyword=Sodium chloride kn-keyword=Sodium chloride en-keyword=Apatite-forming ability kn-keyword=Apatite-forming ability END start-ver=1.4 cd-journal=joma no-vol=133 cd-vols= no-issue=9 article-no= start-page=555 end-page=561 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250901 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Preparation and structural characterization of nanoporous silica/magnesium(II)-whitlockite composite particles en-subtitle= kn-subtitle= en-abstract= kn-abstract=The preparation of particles composed of nanoporous silica (NS) and Mg2+-whitlockite (Mg-WH) would provide valuable insights for designing particles for biomedical applications. In this study, NS and Mg-WH composite particles were successfully synthesized. The addition of chitosan during synthesis possibly promoted the crystallization of calcium phosphate phases in the composite particles. Pore size distribution analysis of the particles showed a maximum at 3.2 nm. Investigating the adsorption of methylene blue onto the particles in a phosphate buffer (pH 7.4) showed that the saturated adsorption amount of methylene blue on the particles was significantly higher than that on commercial hydroxyapatite. The composite particles provided important results for potential applications as drug carriers for bone regeneration and repair. en-copyright= kn-copyright= en-aut-name=KataokaTakuya en-aut-sei=Kataoka en-aut-mei=Takuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=HirotaDaiki en-aut-sei=Hirota en-aut-mei=Daiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=FujiiEiji en-aut-sei=Fujii en-aut-mei=Eiji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=HayakawaSatoshi en-aut-sei=Hayakawa en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=3 en-affil=Industrial Technology Center of Okayama Prefecture kn-affil= affil-num=4 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=5 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Nanoporous silica kn-keyword=Nanoporous silica en-keyword=Magnesium(II)-whitlockite kn-keyword=Magnesium(II)-whitlockite en-keyword=Composite particle kn-keyword=Composite particle en-keyword=Drug carriers for bone regeneration and repair kn-keyword=Drug carriers for bone regeneration and repair END start-ver=1.4 cd-journal=joma no-vol=133 cd-vols= no-issue=1 article-no= start-page=15 end-page=24 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250101 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Comparative study of the effects of fluoride treatment with cyclic variations in pH on the structures of stoichiometric, calcium-deficient, and carbonated hydroxyapatites en-subtitle= kn-subtitle= en-abstract= kn-abstract=The primary objective of this study was to analyze the effects of fluoride treatment with cyclic variations in pH on the structure of stoichiometric hydroxyapatite (HAp), calcium-deficient HAp (CDHAp), and carbonated HAp (CHAp) powders. The structures of HAp, CDHAp, and CHAp before and after fluoride treatment were investigated using X-ray diffraction, Fourier-transform infrared, Raman, and nuclear magnetic resonance spectroscopic analyses. The fluoride treatment with cyclic variations in pH increased the calcium deficiency in HAp and CHAp but decreased in CDHAp. During fluoride treatment, fluoridated CDHAp or fluoridated calcium-deficient CHAp was formed on the surface of the HAp samples via dissolution and crystal growth, accompanied by the selective elution of component ions and partial substitution of OH− groups in the HAp hexagonal lattice with F− ions. No evidence of the formation of Ca(OH)2 and OH− groups outside the HAp crystal lattice was obtained. A new perspective on the formation of structured water at the surface termination of the OH columns (disordered region), with possible interactions with adsorbed water molecules or nonspecifically adsorbed F− ions was provided. The top surface of the fluoridated CDHAp consisted of an amorphous fluoride-rich hydrated layer, which included calcium phosphate and CaF2. en-copyright= kn-copyright= en-aut-name=HayakawaSatoshi en-aut-sei=Hayakawa en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkadaYu en-aut-sei=Okada en-aut-mei=Yu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Hydroxyapatite kn-keyword=Hydroxyapatite en-keyword=Fluoride treatment kn-keyword=Fluoride treatment en-keyword=Microstructure kn-keyword=Microstructure en-keyword=Calcium fluoride kn-keyword=Calcium fluoride en-keyword=Structured water kn-keyword=Structured water END start-ver=1.4 cd-journal=joma no-vol=112 cd-vols= no-issue=2 article-no= start-page=419 end-page=424 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240909 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Electrochemically assisted sol-gel deposition of bioactive gels for biomedical applications en-subtitle= kn-subtitle= en-abstract= kn-abstract=So far, the sol-gel process has been available to prepare precursor gels of bioactive glasses with various compositions. In this report, we described a novel coating method of bioactive gels on a titanium substrate where the sol-gel transition is controlled by applying external electric fields. The application of a constant current of 10 mA/cm2 in an acidic sol containing pre-hydrolyzed tetraethoxysilane, calcium nitrate, and ammonium dihydrogen phosphate led to the deposition of gels on the titanium cathodes due to the generation of OH– by water electrolysis as a catalyst of the sol-gel transition. The obtained gels, which were characterized to be amorphous and consisted of Si, Ca, and P, covered the titanium substrates as a coating. The bioactivity of the gels deposited was confirmed by soaking in a simulated body fluid (SBF) up to 7 days, suggesting that the electrochemically assisted sol-gel process is promising for providing bioactive coatings on metallic implants. en-copyright= kn-copyright= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MiyamotoNaoki en-aut-sei=Miyamoto en-aut-mei=Naoki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HayakawaSatoshi en-aut-sei=Hayakawa en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Biomaterials Laboratory, Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=3 en-affil=Biomaterials Laboratory, Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Sol-gel-derived gels kn-keyword=Sol-gel-derived gels en-keyword=Coating kn-keyword=Coating en-keyword=Water electrolysis kn-keyword=Water electrolysis en-keyword=Bioactivity kn-keyword=Bioactivity en-keyword=SBF kn-keyword=SBF END start-ver=1.4 cd-journal=joma no-vol=2 cd-vols= no-issue= article-no= start-page=37 end-page=39 dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20220331 dt-online= en-article= kn-article= en-subject= kn-subject= en-title=Activity Report of Research Group for Next-Generation Interdisciplinary Science and Engineering in Health Systems kn-title=統合科学次世代研究会の活動報告 en-subtitle= kn-subtitle= en-abstract= kn-abstract= en-copyright= kn-copyright= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name=吉岡朋彦 kn-aut-sei=吉岡 kn-aut-mei=朋彦 aut-affil-num=1 ORCID= en-aut-name=HikasaHaruka en-aut-sei=Hikasa en-aut-mei=Haruka kn-aut-name=日笠晴香 kn-aut-sei=日笠 kn-aut-mei=晴香 aut-affil-num=2 ORCID= affil-num=1 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil=岡山大学大学院ヘルスシステム統合科学学域 affil-num=2 en-affil=Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil=岡山大学大学院ヘルスシステム統合科学学域 END start-ver=1.4 cd-journal=joma no-vol=292 cd-vols= no-issue= article-no= start-page=110325 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=202103 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Crystallization characteristics of amorphous trehalose dried from alcohol en-subtitle= kn-subtitle= en-abstract= kn-abstract=Trehalose forms a glass that can be used to preserve labile substances under desiccation. The crystallization characteristics, namely crystallization temperature (Tcry) and isothermal crystallization behavior of amorphous trehalose, dried from alcohol (methanol, ethanol), was analyzed and the results were compared with those for the amorphous trehalose freeze-dried from water. The use of alcohol as a solvent lowered the Tcry from 184 ± 6 °C for the case of an aqueous solvent to 103 ± 5 °C/methanol and 120 ± 8 °C/ethanol. The formation of multiple forms of crystals and partial melting were suggested by the thermal analysis. Isothermal crystallization experiments showed that the alcohol-originated amorphous trehalose was eventually exclusively converted into β-form crystals. The induction period (tind) before the start of isothermal crystallization was markedly shortened when alcohol was used as the solvent compared to water. The tind values for various amorphous sugar samples including the alcohol-originated ones could be correlated with difference between Tcry and the sample temperature. en-copyright= kn-copyright= en-aut-name=SekitohTakanari en-aut-sei=Sekitoh en-aut-mei=Takanari kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkamotoTakashi en-aut-sei=Okamoto en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=FujiokaAkiho en-aut-sei=Fujioka en-aut-mei=Akiho kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=TeruiShinji en-aut-sei=Terui en-aut-mei=Shinji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=ImanakaHiroyuki en-aut-sei=Imanaka en-aut-mei=Hiroyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=IshidaNaoyuki en-aut-sei=Ishida en-aut-mei=Naoyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=ImamuraKoreyoshi en-aut-sei=Imamura en-aut-mei=Koreyoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=6 en-affil=Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=8 en-affil=Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=Trehalose kn-keyword=Trehalose en-keyword=Crystallization kn-keyword=Crystallization en-keyword=Anhydrous crystal kn-keyword=Anhydrous crystal en-keyword=Methanol kn-keyword=Methanol en-keyword=Vacuum foam drying kn-keyword=Vacuum foam drying END start-ver=1.4 cd-journal=joma no-vol=7 cd-vols= no-issue=1 article-no= start-page=90 end-page=100 dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190211 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Accelerated induction of in vitro apatite formation by parallel alignment of hydrothermally oxidized titanium substrates separated by sub-millimeter gaps en-subtitle= kn-subtitle= en-abstract= kn-abstract= Although autoclaving is a common sterilization method for biomedical devices, the ability to induce deposition of apatite particles on hydrothermally treated titanium is still not fully realized. This is because the induction ability is too weak to be evaluated via in vitro apatite formation in Kokubo's simulated body fluid (SBF) by the conventional immersion method, i.e. using samples with open and smooth surface. This study reports on the surface structure of hydrothermally treated titanium and the ability to induce deposition of apatite particles on the surface of parallel confined spaces separated by sub-millimeter gaps in Kokubo's SBF. Thin-film X-ray diffraction and analyses using Fourier transform infra-red (FT-IR) spectroscopy and Raman spectroscopy revealed that a nano-crystalline anatase-type titanium oxide layer was formed on titanium substrates after hydrothermal treatment at 150 degrees C for 2 h. When growth of the titanium oxide layer was moderately suppressed, the hydrothermally treated titanium surface exhibited a characteristic interference color, silver or gold, which does not impair the esthetic appearance of the titanium-based implant. The ability to induce deposition of apatite particles on hydrothermally treated titanium was remarkably amplified by parallel alignment of substrates separated by sub-millimeter gaps. en-copyright= kn-copyright= en-aut-name=HayakawaSatoshi en-aut-sei=Hayakawa en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkamotoKeigo en-aut-sei=Okamoto en-aut-mei=Keigo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=2 en-affil=Biomaterials Laboratory, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Titanium substrate kn-keyword=Titanium substrate en-keyword=apatite deposition kn-keyword=apatite deposition en-keyword=simulated body fluid kn-keyword=simulated body fluid en-keyword=parallel alignment kn-keyword=parallel alignment en-keyword=titania layer kn-keyword=titania layer END start-ver=1.4 cd-journal=joma no-vol= cd-vols= no-issue= article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20191202 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Comparative study of in vitro apatite-forming abilities of highly ordered rutile nanorod arrays fabricated on cpTi and Ti6Al4V alloys en-subtitle= kn-subtitle= en-abstract= kn-abstract= The surfaces of commercially available pure titanium (cpTi) and Ti6Al4V alloy specimens were modified to form highly ordered rutile nanorod arrays by chemical treatment and subsequent aging treatment. The densities of the rutile rods were (1.04 +/- 0.06) x10(3) and (0.70 +/- 0.10) x10(3) mu m(-2) for the cpTi and Ti6Al4V alloy specimens, respectively. Both the rutile nanorod arrays on the cpTi and Ti6Al4V alloy specimens deposited apatite particles when soaked in simulated body fluid (SBF) for one day. After soaking for various other periods, scanning electron microscopy images and thin-film X-ray diffraction patterns of these specimens showed that the cpTi specimens exhibited a superior rate of apatite nucleation and favored the formation of numerous apatite particles with larger diameter. This superior apatite-forming ability of the cpTi specimens can be attributed to the dense, thick titania layers with higher rutile nanorod density on their surfaces. en-copyright= kn-copyright= en-aut-name=LiuXingzhu en-aut-sei=Liu en-aut-mei=Xingzhu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YoshiokaTomohiko en-aut-sei=Yoshioka en-aut-mei=Tomohiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HayakawaSatoshi en-aut-sei=Hayakawa en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Biomaterials Laboratory, Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Biomaterials Laboratory, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=3 en-affil=Biomaterials Laboratory, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Rutile kn-keyword=Rutile en-keyword=nanorod arrays kn-keyword=nanorod arrays en-keyword=apatite kn-keyword=apatite en-keyword=rod density kn-keyword=rod density END