Hydroxyapatite-TiO(2)-based nanocomposites synthesized in supercritical CO(2) for bone tissue engineering: physical and mechanical properties

• Published in: ACS applied materials & interfaces 2014-10, Vol.6 (19), p.16918-16931
• Main Authors: Salarian, Mehrnaz, Xu, William Z, Wang, Zhiqiang, Sham, Tsun-Kong, Charpentier, Paul A
• Format: Article
• Language: English
• Subjects: Bone and Bones - drug effects; Calcium - analysis; Carbon Dioxide - pharmacology; Durapatite - pharmacology; Humans; Materials Testing - methods; Nanocomposites - chemistry; Nanocomposites - ultrastructure; Phosphorus - analysis; Photoelectron Spectroscopy; Polyesters - chemistry; Powders; Spectrometry, X-Ray Emission; Spectroscopy, Fourier Transform Infrared; Temperature; Thermogravimetry; Tissue Engineering - methods; Titanium - pharmacology; X-Ray Absorption Spectroscopy; X-Ray Diffraction
• ISSN: 1944-8252
• DOI: 10.1021/am5044888

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.