Papers by Keyword: Osteoconductivity

Abstract: The cytocompatibility of the poly (dimethylsiloxane) (PDMS) surfaces can be improved by the coating with biomaterials. In this study, the methodology for the particulate titania (PT) coating on the PDMS film was investigated via the combined process of microfluidic synthesis system with spin-coating, leading to the one-step synthesis and coating. The PT was successfully deposited on the O₂-plasma-treated PDMS films by mixing titanium tetraisopropoxide, isopropyl alcohol, water and octadecylamine in a microfluidic reactor and subsequently dropping. The rotation speed in the spin-coating plays an important role in the PT morphologies and deposition amounts on the PDMS films. Through the detailed investigation, the efficient condition for adhering PT to PDMS as well as inducing apatite formation from simulated body fluid was successfully discovered.

Abstract: MC3T3-E1 cell differentiation and related surface potentials of rutile-type TiO₂ scales formed on Ti are controlled by varying the Ti heat treatment conditions in a N₂ atmosphere containing a trace amount of O₂. The zeta potentials of the samples heated at 873 and 973 K for 1 h show large negative and positive values, respectively, while cell differentiation on the surface is enhanced in both cases (14 days incubation). In the case of untreated Ti, the cell differentiation diminishes and the zeta potential becomes more neutral. Protein detection by an immunogold-labeling technique and Ca and P detection by time-of-flight secondary ion mass spectrometry reveal that Ca and P, rather than an adhesive protein such as fibronectin, predominantly adsorbed on the scales formed in 1 h at 873 and 973 K, respectively. In the case of untreated Ti, both fibronectin and a non-adhesive protein such as albumin adsorbed, but no Ca and P were detected. The present findings illuminate the relationship between charged surfaces and MC3T3-E1 cellular response.

Abstract: The surface potential of the TiO₂ scale formed on Ti was controlled by varying the Ti heat treatment conditions in a N₂ atmosphere containing a trace amount of O₂. The surface potential was attributed to the effective charge of nitrogen-related defects in the TiO₂, where the positive and negative surface charges were associated with (N₂)₀+2 and (NO)₀^-1, respectively. The latter defects were formed only during the early stages of the heat treatment, and with increasing treatment time, this was followed by the formation of voids containing N₂ in the scale rather than the disappearance of the defects in the TiO₂ crystal lattice, resulting in zero surface charge. Hydroxyapatite (HAp) formation and osteoconductivity were enhanced on nitrogen-doped TiO₂ scale with either a positive or negative surface potential. In contrast, for the unchanged TiO₂ scale, no HAp formation was observed and the osteoconductivity was low.

Abstract: We have established a processing method to fabricate three - dimensional porous carbonate apatite (CO₃Ap) with interconnected porous structure and improved mechanical strength. Briefly, porous CO₃Ap materials were produced via phosphorization of porous calcite precursor in hydrothermal condition. In order to make porous calcite precursor, negative replication of modified polyurethane foam template was conducted. In this study, an in vivo behavior of that porous CO₃Ap was evaluated. The interconnected porous CO₃Ap material was implanted in the tibia of Japanese male rabbits and removed after a period of 6 months. Micro-computed tomography (μ-CT) scanner and histological analysis were used to characterize the bone formation response of the porous CO₃Ap. The results suggest that porous CO₃Ap with enhanced mechanical strength was not only osteoconductive but also bioresorbable therefore it could be used as bone substitute material.

Abstract: Regulation of DCPD formation on β-TCP granules was achieved by exposing β-TCP granular with different concentration of acidic calcium phosphate solution. It was found that a higher amount of DCPD was formed when exposed β-TCP granular with the higher concentration of acidic calcium phosphate solution. Morphological observation shows that the surface of β-TCP granular was fully coated with DCPD crystals after exposed with the higher concentration of acidic calcium phosphate solution. These results demonstrated that the DCPD formation on the β-TCP granular surface could be regulated by varying the concentration of acidic calcium phosphate solution.

Abstract: In this study, we conferred superhydrophilic properties on anodized TiO₂ coatings using a hydrothermal treatment, and developed a method to maintain this surface until implantation. The osteoconductivity of these coatings was evaluated with in vivo tests. A hydrothermal treatment made the surface of as-anodized samples more hydrophilic, up to a water contact angle of 13 deg. Storage in PBS(-) led to a reduction in the water contact angle, because of the adsorption of the inorganic ions in the solution, and the sample retained its high hydrophilicity for a long time. As the water contact angle decreased, the hard tissue formation ratio increased continuously up to 58 %, which was about four times higher than the hard tissue formation ratio on as-polished Ti.

Abstract: Anti-corroded valve metals, such as Ti, Nb, Ta, and Zr have been used as metallic biomaterials. However, as untreated surfaces, they do not have high osteoconductivity, and surface coatings with bioactive substances are needed for the implantation into the bone. Surface property, especially hydrophilicity, is considered to have a strong influence on the biological reactions. However, the influence of a hydrophilic surface on osteoconductivity is not completely clear. In this study, we produced super-hydrophilic surface on valve metals (Ti, Nb, Ta and Zr) using a hydrothermal treatment at 180 °C for 180 min. in the distilled water, and then the treated samples were stored in 5PBS(-). This maintained water contact angle less than 10 (deg.) in an apparent. The osteoconducivity of super-hydrophilic treated metals was evaluated with in vivo tests. The hard tissue formation on the samples increased with decreasing the water contact angle. That is to say that super-hydrophilic valve metals without coating of bioactive substances had high osteoconductivity, and the surface properties strongly affected on the osteoconductivity.

Abstract: MC3T3-E1 cell responses, such as cell adhesion and proliferation, to original and bovine serum albumin (BSA) coated disc (original-disc, BSA-disc) of hydroxyapatite (HA) or alpha-type alumina (α-Al₂O₃) was studied. There was no significant difference in the cell proliferation between BSA-discs and original-discs even after incubated for 14 days, but the cell number at day 14 tended to be higher (p = 0.054) on the BSA-discs of HA than on the original-discs of HA. Incidentally, the amount of adsorbed protein was higher on BSA-discs than on original-discs only until incubated in culture medium for 3 h. BSA adsorption might influence the MC3T3-E1 cell adhesion to HA, as a result the specific adsorption of albumin on HA is likely to affect the expression of the osteoconductivity of materials.

Abstract: We are developing a new bone paste (CaNaP paste), consists of calcium sodium phosphate (CaNaPO₄), alpha-TCP, beta-TCP and citrate. It has improved handling and mechanical property with decreased setting time. For in vivo analysis using a rabbit model, four kinds of materials (Material 1: CaNaPO₄ + alpha, beta-TCP + citrate, Material 2: commercially available CaP paste, Material 3: CaNaPO₄ + alpha-TCP + citrate, and Material 4: commercially available porous beta-TCP) were prepared, and they were implanted into the rabbit femoral condyles (n=8). After 4 weeks and 12 weeks, histo-morphometrical analyses were performed, and bone-material contact index, bone area in the material, bone area ratio around the material, degree of bone penetration into the material, and material absorptivity were calculated. Results showed that Material 1 (newly developed CaNaP pasted containing beta-TCP) is more osteoconductive than Material 2 and Material 3 (CaNaP paste without beta-TCP), and can be expected as an attractive alternative for the bone substitute material.

Abstract: To improve surface hardness of dental implant made of pure titanium (Ti), titanium nitride (TiN) coating was introduced. However, studies revealed that TiN only showed osseointegration similar or inferior to that of Ti. Therefore it is necessary to improve the biocompatibility of TiN for dental implant coating. In the present study, TiN coating was prepared on pure Ti substrates and hydrothermal treatment was conducted to modify its surface properties. It was found that, TiN surface was partially oxidized after treatment and calcium (Ca) was successfully combined onto its surface. Surface morphology, roughness and hardness were not affected after treatments below 140°C and wettability was obviously improved.