title: Hydroxyapatite-TiO(2)-based nanocomposites synthesized in supercritical CO(2) for bone tissue engineering: physical and mechanical properties.
abstract: Calcium phosphate-based nanocomposites offer a unique solution toward producing scaffolds for orthopedic and dental implants. However, despite attractive bioactivity and biocompatibility, hydroxyapatite (HAp) has been limited in heavy load-bearing applications due to its intrinsically low mechanical strength. In this work, to improve the mechanical properties of HAp, we grew HAp nanoplates from the surface of one-dimensional titania nanorod structures by combining a coprecipitation and sol-gel methodology using supercritical fluid processing with carbon dioxide (scCO2). The effects of metal alkoxide concentration (1.1-1.5 mol/L), reaction temperature (60-80 °C), and pressure (6000-8000 psi) on the morphology, crystallinity, and surface area of the resulting nanostructured composites were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) method. Chemical composition of the products was characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure (XANES) analyses. HAp nanoplates and HAp-TiO2 nanocomposites were homogeneously mixed within poly(ε-caprolactone) (PCL) to develop scaffolds with enhanced physical and mechanical properties for bone regeneration. Mechanical behavior analysis demonstrated that the Young's and flexural moduli of the PCL/HAp-TiO2 composites were substantially higher than the PCL/HAp composites. Therefore, this new synthesis methodology in scCO2 holds promise for bone tissue engineering with improved mechanical properties.
authors.affiliation: Biomedical Engineering Graduate Program, University of Western Ontario , London, Ontario N6A 5B9, Canada.
authors.forename: Mehrnaz
authors.initials: M
authors.lastname: Salarian
authors.forename: William Z
authors.initials: WZ
authors.lastname: Xu
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Wang
authors.forename: Tsun-Kong
authors.initials: TK
authors.lastname: Sham
authors.forename: Paul A
authors.initials: PA
authors.lastname: Charpentier
mesh_terms: D001842:Bone and Bones / Q000187:drug effects*; D002118:Calcium / Q000032:analysis; D002245:Carbon Dioxide / Q000494:pharmacology*; D017886:Durapatite / Q000494:pharmacology*; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D010758:Phosphorus / Q000032:analysis; D056951:Photoelectron Spectroscopy; D011091:Polyesters / Q000737:chemistry; D011208:Powders; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013818:Thermogravimetry; D023822:Tissue Engineering / Q000379:methods*; D014025:Titanium / Q000494:pharmacology*; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
chemical_list: D011091:Polyesters; D011208:Powders; D002245:Carbon Dioxide; C009495:titanium dioxide; C016240:polycaprolactone; D010758:Phosphorus; D017886:Durapatite; D014025:Titanium; D002118:Calcium
keywords: hydroxyapatite−titania nanocomposite; mechanical properties; morphology; sol−gel method; supercritical carbon dioxide