Microstructural properties of novel nanocomposite material based on hydroxyapatite and carbon nanotubes: fabrication and nonlinear instability simulation

Abstract

In this work, a novel porous bio-nanocomposite material containing the commercial nanocrystalline hydroxyapatite (n-HA) composed using single-walled carbon nanotubes (SWCNTs) with different weight fractions (0, 2.5, 5, and 7.5 wt%) is fabricated via a space holder technique for bone tissue engineering applications. The hydroxyapatite (HA) presents a weak mechanical performance which the addition of the SWCNT can enhance the mechanical strength of the matrix. The manufactured n-HA-SWCNT bio-nanocomposite samples are then coated by gelatin-ibuprofen (GN-IBO) bio-polymer with a dip-coating method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) are employed for the phase characterization and surface morphology analysis of the fabricated bio-nanocomposite specimens. The mechanical properties, the rate of drug release, and biological characteristics of the specimens with and without SWCNTs are investigated. After that, the nonlinear instability and vibration responses of an axially loaded plate-form bone implant made of the manufactured n-HA-SWCNT bio-nanocomposite samples coated with GN-IBO thin layers are simulated through a sandwich-plate model and based upon the experimentally extracted mechanical properties. The obtained results indicate the presence of SWCNT and n-HA in the composition due to the fuzzy metamorphism or degradation. It is found that by increasing the amount of SWCNTs, the mass density of the fabricated bio-nanocomposite samples reduces, but the porosity and strength of them are higher than those of the pure n-HA. Therefore, it is expected that these newly manufactured bio-nanocomposites have an excellent capability for bone formation with better bonds with surrounding tissues.