Single-walled carbon nanotubes loaded hydroxyapatite-alginate beads with enhanced mechanical properties and sustained drug release ability.

Single-walled carbon nanotubes (SWCNTs) containing biomaterial with enhanced mechanical properties for the potential orthopedic application were synthesized and investigated. X-ray diffraction and X-ray fluorescence analysis were indications of the formation of calcium-deficient (Ca/P = 1.65) hydroxyapatite (HA) with a small carbonate content under influence of microwave irradiation. The investigated mechanical properties (maximal relative deformation, compressive strength and Young's modulus) of SWCNT loaded HA-alginate composites confirm their dependence on SWCNTs content. The compressive strength of HA-alginate-SWCNT and the HA-alginate control (202 and 159 MPa, respectively) lies within the values characteristic for the cortical bone. The addition of 0.5% SWCNT, in relation to the content of HA, increases the Young's modulus of the HA-alginate-SWCNT (645 MPa) compared to the SWCNT-free HA-alginate sample (563 MPa), and enhances the material shape stability in simulated physiological conditions. Structural modeling of HA-alginate-SWCNT system showed, that physical adsorption of SWCNT into HA-alginate occurs by forming triple complexes stabilized by solvophobic/van der Waals interactions and H-bonds. The high-performance liquid chromatography demonstrated the influence of SWCNTs on the sustained anaesthesinum drug (used as a model drug) release (456 h against 408 h for SWCNT-free sample). Cell culture assay confirmed biocompatibility and stimulation of osteoblast proliferation of 0.05% and 0.5% SWCNT-containing composites during a 3-day cultivation. All these facts may suggest the potential possibility of using the SWCNT-containing materials, based on HA and alginate, for bone tissue engineering.

Composite material based on hydroxyapatite and multi-walled carbon nanotubes filled by iron: Preparation, properties and drug release ability.

The novel bioactive composite material based on hydroxyapatite and multi-walled carbon nanotubes filled by iron was synthesized by the "wet chemistry" method and characterized in detail by various experimental techniques including the X-ray diffraction, Fourier transform infrared and energy-dispersive X-ray fluorescence spectroscopy, thermogravimetric and differential thermal analysis. The swelling behaviour was quantified by measuring the changes in sample weight as a function of sample immersion time in a phosphate buffered saline (PBS). Bioactivity test was carried out by soaking the samples in PBS. The material composition influence on the model drug release was studied using the high-performance liquid chromatography method. Finally, the mechanical properties (maximal relative deformation, strength and Young's modulus) of the samples under loading were investigated too. The findings clear demonstrate the possibility of application of the created composite material in bioengineering of bone tissue to fill bone defects of various geometries with the function of prolonged release of the drug. It is assumed that this composite material can be used in 3D modeling of areas of bone tissue that have to bear a mechanical load.