Effects of Mg‐Doping and of Reinforcing Multiwalled Carbon Nanotubes Content on the Structure and Properties of Hydroxyapatite Nanocomposite Ceramics

Surfactant‐assisted hydrothermal synthesis of magnesium‐doped hydroxyapatite (Ca_10?xMg_x(PO₄)₆(OH)₂) with 0 ≤ x ≤ 1) was realized in aqueous solution at 90°C. β‐TCP phase was formed in the Mg_0.6‐HA sample after heat treatment at 1000°C. Magnesium was found to degrade the sintering ability of Mg_x‐HA ceramics. Flexural strength (σ_f) was found to decrease as a function of Mg‐doped HA. The using of carbon nanotubes as reinforcing agents mitigated the strength loss of Mg‐HA ceramics. The flexural strength of Mg_0.6‐HA was then increased by nearly 20% from approximately 33 to 39 MPa with an optimum addition of 3 wt% of multi‐walled nanotubes.     

A comprehensive study on copper incorporated bio-glass matrix for its potential antimicrobial applications

In this study, sol-gel derived Cu substituted 70S bioglass (70SiO2-(20-x) CaO–10P2O5-xCuO; where x = 0, 0.5, 1, 1.5) were synthesized as a new multifunctional bioactive glasses (BGs). The effect of Cu substitution in the bio-glass matrix was evaluated for its impact on pathogen (Escherichia coli and Staphylococcus aurous). Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD), Inductively Coupled Plasma spectroscopy (ICP) and Scanning Electron Microscopy (SEM) revealed that the obtained powders are amorphous silicate glass. The substituted element is present in the desired molar concentration. In vitro bioactivity test was performed in SBF solution by immersion of bioglass pellets. Antibacterial test was carried out against Escherichia coli and Staphylococcus aureus. The results showed that the prepared BGs have a high acellular bioactivity observed by a fast formation of thick and continuous layer of carbonated hydroxyapatite (CHA). The antibacterial properties of the substituted bio-glass matrix was indicated by the growth inhibition of bacterial colonies. The obtained results showed that copper substituted bio-glass is having potential to avoid post-surgical infections and it also represents the capability of hard tissue regeneration.     

Hydrothermal Synthesis of Si‐doped Hydroxyapatite Nanopowders: Mechanical and Bioactivity Evaluation

Si‐doped hydroxyapatite nanoparticles (n‐Si_xHA) were prepared by hydrothermal synthesis from calcium nitrate tetrahydrate and diammonium hydrogen orthophosphate. A rod‐like morphology was obtained for all the powders irrespective of the incorporated Si‐doping level. But the crystallinity of the n‐Si_xHA powders, the density achieved upon sintering powder compacts and their mechanical properties (three‐point‐bending strength), as well as their biomineralization activity evaluated by immersing them into simulated body fluid (SBF) were found to be dependent on the Si‐doping amount.