Papers by Keyword: α-Tricalcium Phosphate (α-TCP)

Abstract: Functionally graded Ca-Ti-O/Ca-P-O films were prepared by MOCVD. The phases, composition and morphology of Ca-Ti-O and Ca-P-O films changed depending on the molar ratio of each precursors, total pressure (Ptot) and substrate temperature (Tsub). CaTiO3 films in a single phase were obtained at Tsub = 973 and 1073 K. CaTiO3 films prepared at 873 K had a dense and smooth surface, whereas that prepared at Tsub = 1073 K had complicated rough surface with a cauliflower-like texture. The graded texture of CaTiO3 films from columnar to fine grains was advantageous to good adherence for metal substrates. -TCP and HAp films in a single phase were obtained at Tsub = 973 and 1073 K. Both -TCP and HAp films had a dense and smooth surface. The maximum deposition rate of Ca-Ti-O and Ca-P-O films were 44 and 20 m/h, respectively, and several 10 times grater than that of sputtering method. Apatite formation rate strongly depended on the surface morphology of film. Apatite formed after 3 days on the CaTiO3 film, 14 days on the -TCP film and 6 hours on the HAp film in a Hanks’ solution.

Abstract: In this study, a biocomposite comprising nanostructured α-tricalcium phosphate (α-TCP) in a poly(D,L-lactic-co-glycolic acid) (PLGA) matrix was fabricated by a modified solution evaporation method. As a potential temporary bone fixation and substitution material, its bioactivity was evaluated by its ability to form bone-like apatite layer in simulated body fluid (SBF). Owing to the increased surface area covered by the osteoconductive bioceramic of α-TCP, rapid apatite formation was observed. After 7 days of immersion, enhanced nucleation of apatite was observed on the nanocomposite. At day 14, dense lamellar-like apatite was formed on the nanocomposite whilst apatite nucleation had only just started to develop on the surface of pure PLGA. At the same time, a preliminary in-vitro cell culture study was conducted using human osteoblast-like (HOB) cells. A significant increase in cell number with culturing time was observed for the nanocomposite. After 9 days incubation, a confluent lamellar-like apatite layer was formed on the composite surface. This apatite layer was also shown beneath the proliferating HOB cells at Day 16.

Abstract: Apatite foam (AP foam) is an ideal material for bone substitutes and scaffolds in bone tissue regeneration. This is because its highly porous interconnected pores provide the space for cell growth and tissue penetration, and that its composition induces excellent tissue response and good osteoconductivity. In the present study, the feasibility of apatite foam fabrication was evaluated based on so-called dissolution-reprecipitation reaction of α-tricalcium phosphate (α-TCP) foam granules. When α-TCP foam granules were placed in water at 37°C for 24h, no reaction was observed. However, α-TCP foam set to form AP foam when treated hydrothermally at 200°C. The network of fully interconnected pores was retained, and porosity was as high as 82%. Pore size ranged from 50 to 300 0m with average pore size at 160 0m. Compressive strength was 207 kPa. Although no setting reaction was observed at 37°C, setting reaction caused by hydrothermal treatment of α-TCP foam granules at 200°C allows AP foam of any shape to be fabricated. Therefore, this method was suggested to be useful for the fabrication of bone substitutes and the scaffold in bone tissue regeneration.

Abstract: The present work suggests a modified gel casting process, including polyethylene wax spheres addition to the suspension with the objective of creating uniform and interconnected pores in the body of samples. In the present study, apatite powders were synthesized at pH 10 and pH 12 in order to give rise to biphasic and triphasic bioceramics after sintering.

Abstract: Calcium phosphate films were prepared by MOCVD using Ca(dpm)2 and (C6H5O)3PO precursors. The phases, composition and morphology of films changed depending on the molar ratio of Ca to P precursors (RCa/P), total pressure (Ptot) and substrate temperature (Tsub). α-tricalcimu phosphate (α-TCP, α-Ca3(PO4)2) films in a single phase were obtained at Tsub = 1073 K, 0.1 < RCa/P < 0.4 and Tsub = 973 K, RCa/P < 0.4. Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) films in a single phase were obtained at Tsub = 1073 K, 0.8 < RCa/P < 1.0 and Tsub = 973 K, 0.5 < RCa/P < 0.6. Ca-P-O films had a dense and smooth surface. HAp formed within 1 day on the α-TCP film and wholly covered the specimens within 2 weeks in a Hanks’ solution. The surface of CVD-HAp film was covered by precipitated HAp within 6 hours.

Abstract: Unsintering macroporous calcium phosphate scaffolds with macropore sizes of 200∼400μm and hydroxyapatite nanofiber of in-situ growth were prepared by coating porous polyurethane templates with α-tricalcium phosphate bone cement (CPC) slurry, and their subsequent hydrolysis to calcium deficient hydroxyapatite (HAp) during the self-setting processes are presented. The effects of Sr2+ (SrNO3) on the nucleation, growth of the hydroxyapatite nanofiber and phase constitution were studied. The results show that the main component of the coating is HA after hydrolysis for 72h and the Sr2+ added could depress the growth of block or sheet HA crystal and promote the nanowhisker growth. This new processing technique can be used to improve the bioactivity of porous polymer template while maintaining its macroporous structure.

Abstract: Calcium sulphate hemihydrate/α-tricalcium phosphate (CSH-TCP) cement are promising bone replacement materials with controllable-degradation rate and setting time and excellent delivery matrix for sustained release. In the present study, setting behaviors of binary bone cement composed of α-TCP and CSH and release of ciprofloxacin from this cement were investigated in vitro. XRD and SEM results demonstrated that the setting products of CSH-TCP cement were calcium sulphate dihydrate with pillar morphology and hydroxyapatite with needle morphology. Only 20% ciprofloxacin was released from CSH-TCP cement in 7 days in vitro. Fibers of hydroxyapatite enhanced strength of binary cement through fiber-reinforce mechanism. At initial stage (less than 100 hours), the release of ciprofloxacin from CSH-TCP cement was diffusion control, and at subsequent stage the release was matrix dissolution & diffusion control.

Abstract: The purpose of this study was to determine if a strontium (Sr)-containing mixing liquid could be used as an exchanging agent for calcium phosphate cement crystallized with Sr-replacing hydroxyapatite (Sr-HAP). Alpha-tricalcium phosphate (α-TCP) powder was mixed with Srcontaining and phosphorous (P)-containing solutions, that is, SrCl2 or SrCl2+CaCl2 solution and NaH2PO4 or Na2HPO4 solution. After storage in the incubator for 7 days, the α-TCP crystals in all set cements were confirmed to have been transformed to HAP crystals by the mixing liquids. The XRD patterns of the set cements implied that the Sr-HAP could be precipitated by using Srcontaining solutions as the mixing liquid because of the chemical shift of a peak (002) in XRD of the HAP crystal. The solubility (shaking immersion in physiological saline) of set cements containing Sr was markedly higher than that of set cement not containing Sr. These results revealed that the Sr-containing solutions used as mixing liquids for α-TCP cement acted as precipitating agents for Sr-HAP. Sr-HAP-precipitating cement could be useful because of its pharmacological activity with high solubility.

Abstract: α-tricalcium phosphate (α-TCP) was prepared by a wet precipitation reaction between calcium hydroxide and orthophosphoric acid solutions. The as-synthesised powder was then characterised using a Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectroscope (EDS), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscope (FTIR). Analyses revealed that a phase-pure powder with a Ca/P ratio of 1.5 was produced. In addition, nanosized α-TCP particles of diameter ~ 70 nm were agglomerated to form larger particles of 10μm in diameter. It was found that by the combination of attritor milling and solution evaporation, the agglomerates of α-TCP nanoparticles could be broken down, and distributed evenly within the poly(D,L-lactic-co-glycolic acid) (PLGA) matrix. Thus, a α-TCP/PLGA nanocomposite was successfully produced by a modified solution evaporation method at room temperature followed by hot pressing at 150 °C. The achievable ceramic loading was approximately 38 wt.%, which was confirmed by thermal gravimetric analysis (TGA).