Flower-like Brushite structures on Mg. Smart bio-coatings for controlled degradation rates

Globally, each year millions of patients undergo clinical transplant procedures to replace damaged or diseased bone tissues..

Synthesis of a bone like composite material derived from waste pearl oyster shells for potential bone tissue bioengineering applications

Background: Hydroxyapatite is generally considered a viable substitute for bone in a number of medical procedures such as bone repair, bone augmentation and coating metal implants. Unfortunately, hydroxyapatite has poor mechanical properties that make it unsuitable for many load bearing applications. Methods: In the present work various grades of finely crushed Pinctada maxima (pearl oyster shell) were combined with a nanometer scale hydroxyapatite powder to form novel composite materials. A comparative study was made between the various powder based composites synthesized. The crystalline structure and morphology of the various powder based composites were investigated using X-ray diffraction and field emission scanning electron microscopy. The composite materials were also evaluated and characterized. Results: Manufactured hydroxyapatite powders were composed of crystalline spherical/granular particles with a mean size of 30 nm. Also produced were hydroxyapatite and finely crushed calcium carbonate from Pinctada maxima (pearl oyster shell) powder mixtures. Hydroxyapatite coatings produced on Pinctada maxima nacre substrates were investigated and their surface characteristics reported. Conclusions: Pinctada maxima nacre pre-treated with sodium hypo chlorate before hydroxyapatite deposition produced a superior coating and could be used for bone tissue engineering. But further in vitro and in vivo studies are needed to validate the biocompatibility and long term stability of this composite coating

Enhanced deposition and reflective properties of thin aluminium films by substrate vibration

The influence of substrate's vibration during vacuum deposition of aluminium thin films on copper substrates was examined. Aluminium metal was evaporated in specially designed vacuum chamber using the hot-filament technique. Copper substrates were subjected to a vibration of 7.6 kHz during deposition. The Al coatings were identified using X-ray diffraction spectroscopy and scanning electron microscopy was used to examine the resulting microstructures deposited on the substrates. Coatings deposited under substrate vibration had fewer particles, spherical in shape and deposited over uniformly over the entire surface. This was not the case for the non-vibrated substrates, which tended to have much more densely packed granular shaped particles. The reflectivity experiments revealed that vibrated substrates were superior to the non-vibrated substrates by 28 %, while the difference in the thermal response was around 14 %

Vertically aligned CuO nanometre scale wires synthesized by thermal oxidation in atmospheric air

In this study vertically aligned copper oxide (CuO) nanometre scale wires were synthesized via two thermal oxidation techniques. The first involved the direct heating of an oxygen free copper substrate on a commercial hotplate at 300 ºC, while second technique involved heat treating a similar copper substrate in a tube furnace over the temperature range from 400 ºC to 600 ºC. Both heat treatments were carried out in atmospheric air without the use of any catalysts. The as-grown CuO wires formed using this facile thermal oxidation were found to have high aspect ratios, mechanically stable and firmly attached to the underlining oxide layer. The size, shape, morphology and composition of the wires were investigated using advanced characterisation techniques such as transmission electron microscopy, field emission scanning electron microscopy and X-ray diffraction

Rapid sonochemical synthesis and characterisation of copper oxide nanoparticles from Schweizer's Reagent

The present work reports the results of a study that investigated a sonochemical approach to synthesis copper oxide nanostructures from tetraamminediaquacopper dihydroxide. (Schweizer's Reagent). Ultrasonic irradiation ranging from 0 to 400 W over time periods ranging from 5 min to 15 min were performed on Schweizer's reagent. UV-visible spectroscopy has shown that copper nanoparticles are initially formed but soon oxidize in the ultrasonically treated reagent. Formation of copper oxide nanostructures was indicated by the original blue colour of the reagent turning brown at particular power settings. XRD analysis confirmed the presence of both copper (I) oxide (Cu2O) and copper (II) oxide (CuO) at the end of the ultrasonic treatment. SEM microscopy revealed particles sizes ranged from 200 nm up to 1µm and were predominantly granular and agglomerated in nature

The mechanical properties of a porous ceramic derived from a 30 nm sized particle based powder of hydroxyapatite for potential hard tissue engineering applications

In this paper, synthesised nanometre sized hydroxyapatite (nano-HAP) powders composed of spherical 30 ± 5 nm particles were compacted and sintered at temperatures ranging from 650 to 1250℃ to form ceramics of varying porosity and mechanical strength. The size, crystalline structure and morphology of both the synthesised nano-HAP particle powders and the compacted and sintered ceramics were investigated using both X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). Further characterisation techniques such as Brunauer-Emmett-Teller (BET) particle surface area, porosity, bulk density, Vickers hardness and yield strength at various sintering temperatures were tested on sintered pellets and evaluated

Modelling the crystal structure of a 30 nm sized particle based hydroxyapatite powder synthesised under the influence of ultrasound irradiation from X-ray powder diffraction data

Hydroxyapatite (HAP) is a biocompatible ceramic that is widely used in a number of biomedical applications and devices. Due the close similarity between nanometer scale forms of HAP and the mineral phase found in the natural bone matrix, recent studies have focused on understanding the structure of HAP for its inclusion in a new generation of novel composites. In this study two commercially available software packages MaterialsStudioand Endeavour®1.7b were used to model the crystal structure of a nanometre scale HAP powder from X-ray powder diffraction data. The nanometre scale HAP used in this study was prepared via a wet precipitation technique under the influence of ultrasonic irradiation. The main reactants in this process were[Ca(NO3)2] and[KH2PO4], while[NH4OH] was used as the precipitator. During the process the calcium phosphate ratio was set at 1.67 and the pH was maintained at 9. The resultant slurries were then thermally treated in radiant tube furnace to produce nanometre scale particles with a mean diameter of 30 nm

Effect of dilute gelatine on the ultrasonic thermally assisted synthesis of nano hydroxyapatite

A series of nano hydroxyapatite-gelatine composites with different dilute solutions of gelatine concentrations were synthesized by a thermally assisted low-power ultrasonic irradiation method. The gelatine hydroxyapatite, (Gel-HAP) nanoparticles were prepared using Ca(NO3)2 and KH 2PO4 in the presence of gelatine in an aqueous solution. The synthesised products were heat treated between 100 and 400 °C. The effect of the addition of gelatine on the nucleation and growth of synthesised nano HAP was investigated. Characterisation was performed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR). The characterisation results indicate that gelatine has been appended to the nano HAP forming regular spherical shaped crystals of nano sized Gel-HAP

Nanometre scale hydroxyapatite ceramics for bone tissue engineering

The consequences of bone traumatisation, loss or damage, resulting from injury or disease can dramatically reduce the quality of life for a patient at a significant socioeconomic cost.The aim of bone tissue engineering is not only to repair, but also to initiate natural bone regeneration. The ultimate goal is to develop a synthetic tissue scaffold that uses biocompatible materials to produce an effective functional replacement for damaged bone tissue. Thus, avoiding all the problems associated with current bone transplantation procedures. However, repairing and regenerating damaged bone tissue is still a challenging task. Since the skeletal tissues are complex and the presence of foreign materials used to construct a tissue scaffold within the body’s environment will initiate an inflammatory response, which ultimately leads to failure of the repair procedure. This review discusses a number of materials currently being used or has the potential to be used in bone tissue engineering applications. In particular, the advantages and limitations of hydroxyapatite are discussed at length, since its desirable properties such as biocompatibility, bioactivity, osteoconductivity and osteoinductivity make it an ideal starting material for bone tissue engineering applications

The synthesis, characterisation and in vivo study of a bioceramic for potential tissue regeneration applications

Hydroxyapatite (HAP) is a biocompatible ceramic that is currently used in a number of current biomedical applications. Recently, nanometre scale forms of HAP have attracted considerable interest due to their close similarity to the inorganic mineral component of the bone matrix found in humans. In this study ultrafine nanometre scale HAP powders were prepared via a wet precipitation method under the influence of ultrasonic irradiation. The resulting powders were compacted and sintered to form a series of ceramic pellets with a sponge-like structure with varying density and porosity. The crystalline structure, size and morphology of the powders and the porous ceramic pellets were investigated using advanced characterization techniques. The pellets demonstrated good biocompatibility, including mixed cell colonisation and matrix deposition, in vivo following surgical implantation into sheep M. latissimus dorsi