Biosynthesis of Bonelike Apatite 2D Nanoplate Structures Using Fenugreek Seed Extract

An innovative, biomimetic, green synthesis approach was exploited for the synthesis of humane and environmental friendly nanomaterials for biomedical applications. Ultrafine bonelike apatite (BAp) 2D plate-like structures were prepared using fenugreek seed extract during the biosynthesis wet-chemical precipitation route. The chemical analysis, morphology and structure of the prepared 2D nanoplates were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-OES), electron microscopy (SEM and TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. A 2D plate-like nanostructure of BAp with an average width (length) of 12.67 ± 2 nm and thickness of 3.8 ± 1.2 nm was obtained. BAp 2D crystals were tuned by interaction with the fenugreek organic molecules during the fabrication process. In addition to Ca and P ions, bone mineral sources such as K, Mg, Na, SO4 and CO3 ions were incorporated into BAp nanoplates using fenugreek seed extract. The overall organic molecule concentration in the reaction process increased the effectiveness of hydroxyl groups as nucleation sites for BAp crystals. Accordingly, the size of the biosynthesized BAp plate-like structure was reduced to its lowest value. Biosynthesis BAp 2D plate-like nanocrystals showed good viability and higher growth of MC3T3 osteoblast-like structures than that of the control sample. BAp 2D nanoplates prepared by a facile, ecofriendly and cost-effective approach could be considered a favorable osteoconductive inorganic biomaterial for bone regeneration applications.

Fabrication of Bioactive Stainless Steel by the Function of Apatite Nuclei

Micropores were formed on the surfaces of stainless steel (SUS) by sandblasting methods and Apatite Nuclei (AN) were formed in the pores. By this treatments, a bioactive SUS was fabricated. Apatite-forming ability of the SUS was evaluated by immersing in an acellular simulated body fluid. Formation of bonelike apatite was induced on the surface of the SUS within 1 day. High bonding strength of the bonelike apatite layer was achieved by a mechanical interlocking effect between the bonelike apatite formed in the pores and the SUS specimen.

Enzyme Immobilization by Using Apatite Microcapsules with Magnetic Properties

Apatite Nucleus (AN) was attached on the surfaces of maghemite (γ-Fe2O3) particles and soaked them in SBF. By this treatment, formation of bonelike apatite was induced by AN and the apatite covered the whole surface of the γ-Fe2O3 particles. Urease was immobilized on the surfaces of microcapsules and collected by a neodymium magnet. The immobilized urease has an ability of a urea decomposition in an aqueous solution.

Towards Enhanced Bioactivity: Calcium Ion-Doped Polypyrrole

Based on the unique redox property of electrically conductive polymers, Ca2+ was incorporated into polypyrrole (PPy) film that previously doped with polyelectrolyte heparin. Then the apatite-forming ability of the Ca2+-doped PPy was examined by a biomimetic method using stimulated body fluid (SBF), which has ion concentration nearly equal to those of human blood plasma. It was found that the Ca2+-doped PPy successfully formed bonelike apatite deposition on its surface after soaking in SBF for only 3 days, whereas the similar apatite deposition was formed on Ca2+-free PPy after soaking in SBF for 7 days. These indicated that the entrapment of Ca2+ into PPy could accelerate the formation of apatite deposition and the Ca2+-doped PPy was possessed of enhanced bioactivity. It is expected that the Ca2+-doped PPy would be a useful bioactive coating material of metallic medical devices or tissue engineering scaffolds to promote the bone tissue regeneration.

Characterization of HA/Ta Composite Coatings Fabricated by Vacuum Plasma Spraying

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrates have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the low bonding strength between HA and Ti substrates is still problematic in the long-term implantation lifespan. In this paper, HA/Ta composite coatings with various Ta contents (20% and 60%) were fabricated by vacuum plasma spraying (VPS). The microstructure, phase composition of the coatings was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results revealed that the coatings had a rough surface and lamellar structure including some pores. ASTM C-633 standard was used for the measurement of bonding strength, which was found increasing with the increase of Ta contents in the composite coatings. The bonding strength of the composite coating containing 60% Ta (H4T6) reached to 37.2 MPa, which is about 1.9 times that of HA coating. In vitro bioactivity evaluated in simulated body fluids (SBF) showed that bonelike apatite layer was formed on the composite coatings surface, which indicated the good bioactivity of the HA/Ta composite coatings.