Comparative study of in vitro apatite-forming abilities of highly ordered rutile nanorod arrays fabricated on cpTi and Ti6Al4V alloys

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

Accelerated induction of in vitro apatite formation by parallel alignment of hydrothermally oxidized titanium substrates separated by sub-millimeter gaps

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

Preparation of alginic acid layers on solid substrates for biomedical applications

Alginic acid was immobilized on γ-aminopropyltriethoxysilane-coated glass as a model substrate since an alginic acid layer was known to prevent cell adhesion. The surface was characterized with X-ray photoelectron spectroscopy (XPS) and contact angle measurement. The coated substrates adsorbed practically no calcium phosphates on their surfaces when soaked in a simulated body fluid (SBF) of Kolrubo recipe. Since calcium ions are one of the factors for blood clotting, the present alginic acid coating is one of the candidates to improve blood compatibility of clinical materials

Electrophoretic deposition of cellulose nanofibers in aqueous suspensions

Cellulose is one of the most abundant organic polymers in nature and a promising biomass. Since cellulose nanofibers (CNF) have attractive features such as a low thermal expansion coefficient, a high elastic modulus, high mechanical strength, and high eco-friendliness, CNFs are envisaged to be applied for biomaterials, tissue engineering scaffolds, filtration media, and reinforcement in nanocomposites. In this study, in order to develop a coating technology with nanofibers for biomedical applications, CNFs in aqueous suspensions were deposited on titanium and aluminum substrates by an electrophoretic deposition (EPD) technique. CNFs used were obtained from Sugino Machine Ltd. (Japan). Aqueous suspensions of the CNFs were prepared using a wet pulverizing and dispersing device. The obtained 0.2wt% aqueous suspensions of the CNFs were stable and not observed the aggregation of the nanofibers. EPD was conducted in a two-electrode system, where titanium or aluminum sheets were used as anode and a platinum sheet as cathode. The constant voltages of 10-30 V were applied to the system for 10-60 seconds. After the process, it was observed that the CNFs were successfully deposited on the anodes. The deposition amount of CNFs on either anode increased linearly with an increase of the applied time at the constant voltage of 20 V. Moreover, the amount also increased as a function of the applied voltages between 10 to 30 V at the constant applied time of 30 seconds. These results indicated that negatively charged CNFs in the aqueous suspension moved to the anodes by the electrophoresis. The adhesiveness of the deposited CNFs was superior on the aluminum anode compared with the titanium anode, indicating that the interaction between them depended on the kind of metal. In conclusion, EPD of the CNFs paves the way for the development of a coating technology with nanofibers for biomedical applications

Crystallization characteristics of amorphous trehalose dried from alcohol

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

Surgical Resection of Hepatic Cystic Echinococcosis Impaired by Preoperative Diagnosis

Cystic echinococcosis (CE) is a rare afferent infectious disease in Japan. This paper reports a case of a hepatic cyst being diagnosed after surgical resection. A 40-year-old Syrian male was admitted for evaluation of a hepatic cyst. Serum antibodies of echinococcosis were negative. Enhanced computed tomography of the abdomen revealed a large cystic lesion, 9 cm in diameter, in the left lateral sector of the liver, which had many honeycomb-like septa and calcified lesions. Magnetic resonance imaging of this lesion revealed high intensity in the T2 weighted image. We preoperatively diagnosed this lesion as cystadenocarcinoma or CE and performed a left hepatectomy. Pathological examination revealed the presence of protoscolices in the fluid of the cysts and led to a diagnosis of this lesion as CE. In conclusion, on seeing patients with huge hepatic cysts who come from an epidemic area, we should consider hepatic CE

Preparation of chitosan-hydroxyapatite composite mono-fiber using coagulation method and their mechanical properties

Autograft has been carried out for anterior cruciate ligament (ACL) reconstruction surgery. However, it has negative aspect because patients lose their healthy ligaments from other part. We focus on a chitosan-hydroxyapatite (HAp) composite fiber as a scaffold of ligament regeneration. Chitosan- HAp composite fiber was made by using coagulation method. Chitosan-NaH2PO4 solution was coagulated with coagulation bath including calcium ion to get the mono-fiber and then treated with sodium hydroxide solution to form HAp in fiber matrix. The mechanical property of the fiber was improved by the stretching of the wet one because of the orientation of chitosan molecule and the interaction between chitosan and HAp. Maximum stress was improved with increasing of sodium dihydrogen phosphate until 0.03 M. The swelling ratio of the fiber was inhibited by composited with HAp. Additionally, bone-bonding ability was confirmed by SBF soaking tests

Genetic population structure of the precious coral Corallium japonicum in the Northwest Pacific

Population sizes of the Japanese red coral Corallium japonicum have been severely affected by poaching and overfishing. Although genetic structure and connectivity patterns are considered important parameters for conservation strategies, there are few studies focusing on the population genetics of C. japonicum in the Northwest Pacific. We examined the genetic population structure of C. japonicum, in the Northwest Pacific. We used restriction-site-associated DNA sequencing (RAD-seq), which can be used to identify genome-wide single-nucleotide polymorphism (SNPs), to reveal detailed within-species genetic variations. Using the variable SNP loci identified from this analysis, we successfully evaluated the population-level genetic diversity and patterns of gene flow among multiple populations of C. japonicum around Japan. The results of genetic analysis basically showed that gene flow is widely maintained in the geographic range examined in this study, but the analysis in combination with larval dispersal simulations revealed several populations that were genetically distinct from the other populations, suggesting geographically limited gene flows. The information obtained from this study will be useful for the design of effective management schemes for C. japonicum, which is under threat from overfishing