Browsing by Author "Monsees, Thomas K."

Now showing 1 - 4 of 4
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    Biodegradable ceramics consisting of hydroxyapatite for orthopaedic implants
    (MDPI, 2017) Monsees, Thomas K.; Azem, Funda Ak; Cotrut, Cosmin Mihai; Braic, Mariana; Abdulgader, Radwan; Pana, Iulian; Birlik, Isil; Kiss, Adrian; Booysen, Robin; Vladescu, Alina
    This study aims to analyze hydroxyapatite (HAP) coatings enriched with Mg and Ti prepared by a magnetron sputtering technique on Ti6Al4V substrate. For preparation of the coatings, three magnetron targets (HAP, MgO and TiO2) were simultaneously co-worked. The concentration of Mg added was varied by modifying the power applied to the MgO target. In all coatings, the Ti concentration was maintained constant by keeping the same cathode power fed during the whole deposition. The influence of different Mg dopant contents on the formation of phase, microstructure and morphology of the obtained Ti-doped HAP coatings were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Moreover, the effects of Mg addition upon corrosion, mechanical and biological properties were also investigated. Mg- and Ti-doped HAP coating obtained at low radio-frequency (RF) power fed to the MgO target provided material with high corrosion resistance compared to other coatings and bare alloy. A slight decrease in hardness of the coatings was found after the Mg addition, from 8.8 to 5.7 GPa. Also, the values of elastic modulus were decreased from 87 to 53 GPa, this being an advantage for biomedical applications. The coatings with low Mg concentration proved to have good deformation to yielding and higher plastic properties. Biological test results showed that the novel surfaces exhibited excellent properties for the adhesion and growth of bone cells. Moreover, early adherent vital cell numbers were significantly higher on both coatings compared to Ti6Al4V, suggesting that Mg ions may accelerate initial osteoblast adhesion and proliferation.
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    The effect of nigella sativa oil on male reproductive function in male Wistar rats exposed to an obesogenic diet
    (University of Western Cape, 2020) Henkel, Ralf R; Monsees, Thomas K.
    Obesity is a growing public health concern globally, particularly in developed countries such as the United States (US). More than 30% of Americans are considered obese. In the past 20 years in America, incidence of obesity has increased significantly (Mokdad et al., 2003). As a consequence, the Centers for Disease Control (CDC) anticipates that 1 in 3 American adults will be diabetic by 2050 (Boyle et al., 2001; Hedley et al., 2004). The most important cause of obesity is poor nutrition, absence of physical exercise and unfavourable lifestyle changes (James et al., 2001).
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    Examination of the biocompatibility and anti-microbial activity of coated dental implants
    (University of the Western Cape, 2017) Abdulgader, Radwan Salem Sadiq; Monsees, Thomas K.; Africa , Charlene W.J.
    Teeth are important to all people for chewing, speech and aesthetics. Tooth decay, periodontal disease and physical trauma or injuries are the main causes of tooth loss. There are different forms of treatment for tooth loss such as dental bridges, removable dentures and dental implants. Dental implants are considered to be better than the other options. They have artificial tooth roots that are placed in the locations of missing teeth. After surgery, osteoblasts attach to the implant and build new bone around the implant in a process known as osseointegration. Titanium alloys (especially Ti6Al4V) are the most widely used biomedical materials in dental and orthopaedic implants due to their excellent biocompatibility, good mechanical properties and corrosion resistance. Although Ti6Al4V alloy is a favourable material, dental implants can fail (i.e. loosen and eventually fall out). Reasons of dental implant failure are microbial infections, poor surgical execution and biomechanical overloading on the implant surface. Thus, the aim of this study was to evaluate whether specific novel implant coatings could improve the biocompatibility and anti-microbial activity of the standard Ti6Al4V alloy. To that end, the cell adhesion, viability and morphology of SaOS-2 (osteoblast-like) cells were investigated after culturing them on samples of Ti6Al4V coated with hydroxyapatite, magnesium oxide and either titanium dioxide or silicon carbide. Morphology of cells was visualized using phalloidin-TRITC (for actin fibres) and DAPI (for the nuclei), whereas viability was determined using propidium iodide (dead cells) and calcein-AM (live cells) and all were viewed using fluorescence microscopy. The disc diffusion (Kirby- Bauer) assay was used to determine potential antimicrobial activities of the novel implant coatings against Candida albicans, Streptococcus sanguinis, Staphylococcus aureus and Escherichia coli.
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    Sputtered Si and Mg doped hydroxyapatite for biomedical applications
    (IOP Publishing, 2018-01-30) Abdulgader, Radwan; Monsees, Thomas K.
    Hydroxyapatite (HAP) coatings are applied on metallic implant materials to combine mechanical properties of metallic material with bioactivity abilities of HAP ceramic. In this study, HAP coatings with additions of Si and Mg are proposed to be deposited on Ti6Al4V substrates by RF magnetron sputtering. Chemical bonding, morphology, topography and corrosion resistance in simulated body fluids(SBF) of the coatings were investigated. Additionally, mechanical and biological properties of the coatings were evaluated. It was found that the addition of Si and Mg does not influence the formation of a HAP phase. All the coatings exhibited smooth surface and uniform growth, without defects or cracks. Both hardness and elastic modulus of the coated samples decrease with Mg addition in the HAP-Si structure. Both Mg and Si addition into HAP coatings were found to enhance the corrosion resistance of the Ti6Al4V alloy in the SBF solution. Coatings with low Mg content exhibited better corrosion performance. All the coatings investigated were biocompatible, as demonstrated by SaOS-2 bone cell attachment and growth. However, cell proliferation and morphology were inferior on samples with the highest Mg content.