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Apatite Nanocrystals (apatite + nanocrystal)
Selected AbstractsMedical Potentialities of Biomimetic Apatites through Adsorption, Ionic Substitution, and Mineral/Organic Associations: Three Illustrative Examples,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Ahmed Al-Kattan Biomimetic calcium phosphate apatites are particularly adapted to bio-medical applications due to their biocompatibility and high surface reactivity. In this contribution we report three selected examples dealing with mineral/organic interactions devoted to convey new functionalities to apatite materials, either in the form of dry bioceramics or of aqueous colloids. We first studied the adsorption of risedronate (bisphosphonate) molecules, which present potential therapeutic properties for the treatment of osteoporosis. We then addressed the preparation of luminescent Eu-doped apatites for exploring apatite/collagen interfaces through the FRET technique, in view of preparing "advanced" biocomposites exhibiting close spatial interaction between apatite crystals and collagen fibers. Finally, we showed the possibility to obtain nanometer-scaled apatite-based colloids, with particle size tailorable in the range 30,100,nm by controlling the agglomeration state of apatite nanocrystals by way of surface functionalization with a phospholipid moiety. This paper is aimed at illustrating some of the numerous potentialities of calcium phosphate apatites in the bio-medical field, allowing one to foresee perspectives lying well beyond bone-related applications. [source] Fabrication and Drug Delivery of Ultrathin Mesoporous Bioactive Glass Hollow FibersADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Youliang Hong Abstract Ultrathin mesoporous bioactive glass hollow fibers (MBGHFs) fabricated using an electrospinning technique and combined with a phase-separation-induced agent, poly(ethylene oxide) (PEO), are described. The rapid solvent evaporation during electrospinning and the PEO-induced phase separation process demonstrated play vital roles in the formation of ultrathin bioactive glass fibers with hollow cores and mesoporous walls. Immersing the MBGHFs in simulated body fluid rapidly results in the development of a layer of enamel-like apatite mesocrystals at the fiber surfaces and apatite nanocrystals inside the hollow cores. Drug loading and release experiments indicate that the drug loading capacity and drug release behavior of the MBGHFs strongly depends on the fiber length. MBGHFs with fiber length >50,µm can become excellent carriers for drug delivery. The shortening of the fiber length reduces drug loading amounts and accelerates drug release. The MBGHFs reported here with sophisticated structure, high bioactivity, and good drug delivery capability can be a promising scaffold for hard tissue repair and wound healing when organized into 3D macroporous membranes. [source] Growth of osteoblast-like cells on biomimetic apatite-coated chitosan scaffoldsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008I. Manjubala Abstract Porous scaffold materials that can provide a framework for the cells to adhere, proliferate, and create extracellular matrix are considered to be suitable materials for bone regeneration. Interconnected porous chitosan scaffolds were prepared by freeze-drying method, and were mineralized by calcium and phosphate solution by double-diffusion method to form nanoapatite in chitosan matrix. The mineralized chitosan scaffold contains hydroxyapatite nanocrystals on the surface and also within the pore channels of the scaffold. To assess the effect of apatite and porosity of the scaffolds on cells, human osteoblast (SaOS-2) cells were cultured on unmineralized and mineralized chitosan scaffolds. The cell growth on the mineralized scaffolds and on the pure chitosan scaffold shows a similar growth trend. The total protein content and alkaline phosphatase enzyme activity of the cells grown on scaffolds were quantified, and were found to increase over time in mineralized scaffold after 1 and 3 weeks of culture. The electron microscopy of the cell-seeded scaffolds showed that most of the outer macropores became sealed off by a continuous layer of cells. The cells spanned around the pore wall and formed extra cellular matrix, consisting mainly of collagen in mineralized scaffolds. The hydroxyproline content also confirmed the formation of the collagen matrix by cells in mineralized scaffolds. This study demonstrated that the presence of apatite nanocrystals in chitosan scaffolds does not significantly influence the growth of cells, but does induce the formation of extracellular matrix and therefore has the potential to serve for bone tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] The crystallinity of ancient bone and dentine: new insights by transmission electron microscopyARCHAEOMETRY, Issue 3 2002I. Reiche We studied various archaeological and palaeontological bones and dentines from different burial environments by Fourier transform infrared spectroscopy (FT,IR), X,ray diffraction (XRD) and transmission electron microscopy (TEM), in the framework of a general study of diagenesis. FT,IR and XRD were used to evaluate the global preservation state of the bone and dentine mineral phase by determining a splitting factor (SF) or a crystallinity index (CI), respectively. These data can be combined with studies on the nanometer scale made with TEM. This latter technique,coupled with electron microdiffraction, provides determination of dimensions and shapes of individual bone and dentine apatite nanocrystals as well as of secondary minerals formed during diagenesis. It enables us to distinguish between heat,induced recrystallization processes and crystal growth in solution occurring during diagenesis. [source] | ||||||||||