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  • 1.
    Fowler, Lee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman-Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of copper ion concentration on bacteria and cells2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 22, article id 3798Article in journal (Refereed)
    Abstract [en]

    In the oral cavity, dental implants—most often made of commercially pure titanium—come in contact with bacteria, and antibacterial management has been researched extensively to improve patient care. With antibiotic resistance becoming increasingly prevalent, this has resulted in copper being investigated as an antibacterial element in alloys. In this study, the objective was to investigate the copper ion concentrations at which cyto-toxicity is avoided while bacterial inhibition is ensured, by comparing Cu ion effects on selected eukaryotes and prokaryotes. To determine relevant copper ion concentrations, ion release rates from copper and a 10 wt. % Cu Ti-alloy were investigated. Survival studies were performed on MC3T3 cells and Staphylococcus epidermidis bacteria, after exposure to Cu ions concentrations ranging from 9 × 10−3 to 9 × 10−12 g/mL. Cell survival increased from <10% to >90% after 24 h of exposure, by reducing Cu concentrations from 9 × 10−5 to 9 × 10−6 g/mL. Survival of bacteria also increased in the same range of Cu concentrations. The maximum bacteria growth was found at 9 × 10−7 g/mL, probably due to stress response. In conclusion, the minimum inhibitory concentrations of Cu ions for these prokaryotes and eukaryotes were found in the range from 9 × 10−5 to 9 × 10−6 g/mL. Interestingly, the Cu ion concentration correlating to the release rate of the 10 wt. % Cu alloy (9 × 10−8 g/mL) did not kill the bacteria, although this alloy has previously been found to be antibacterial. Further studies should investigate in depth the bacteria-killing mechanism of copper.

  • 2.
    Fowler, Lee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Janson, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Norgren, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman-Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Titanium-Copper alloy as an antibacterial biomaterial2017In: Titanium-Copper alloy as an antibacterial biomaterial, 2017Conference paper (Refereed)
  • 3.
    Fowler, Lee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Masia, Nomsombuluko
    Advanced Materials Division, Mintek, Randburg 2124, South Africa; School of Chemical and Metallurgical Engineering, and DST-NRF Centre of Excellence in Strong Materials, hosted by the University of the Witswatersrand, Johannesburg 2000, South Africa.
    Cornish, Lesley A.
    School of Chemical and Metallurgical Engineering, and DST-NRF Centre of Excellence in Strong Materials, hosted by the University of the Witswatersrand, Johannesburg 2000, South Africa.
    Chown, Lesley H.
    School of Chemical and Metallurgical Engineering, and DST-NRF Centre of Excellence in Strong Materials, hosted by the University of the Witswatersrand, Johannesburg 2000, South Africa.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Norgren, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman-Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Development of antibacterial Ti-Cux alloys for dental applications: effects of ageing for alloys with up to 10wt%Cu2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 23, article id 4017Article in journal (Refereed)
    Abstract [en]

    Peri-implantitis, a disease caused by bacteria, affects dental implants in patients. It is widely treated with antibiotics, however, with growing antibiotic resistance new strategies are required. Titanium-copper alloys are prospective antibacterial biomaterials, with the potential to be a remedy against peri-implantitis and antibiotic resistance. The aim of this study was to investigate Ti-Cux alloys, exploring how Cu content (up to 10 wt%) and ageing affect the material properties. Electron microscopy, X-ray diffraction, hardness testing, bacteriological culture, and electrochemical testing were employed to characterize the materials. It was found that alloys with above 3 wt% Cu had two phases and ageing increased the volume fraction of Ti2Cu. An un-aged alloy of 5 wt% Cu showed what could be Ti3Cu, in addition to the α-Ti phase. The hardness gradually increased with increased Cu additions, while ageing only affected the alloy with 10 wt% Cu (due to changes in microstructure). Ageing resulted in faster passivation of the alloys. After two hours the aged 10 wt% Cu alloy was the only material with an antibacterial effect, while after six hours, bacteria killing occurred in all alloys with above 5 wt% Cu. In conclusion, it was possible to tune the material and antibacterial properties of Ti-Cux alloys by changing the Cu concentration and ageing, which makes further optimization towards an antibacterial material promising.

  • 4.
    Fowler, Lee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Van Vuuren, Arno Janse
    Centre for High Resolution Transmission Electron Microscopy, Department of Physics, Nelson Mandela University, 6031 Port Elizabeth, South Africa.
    Goosen, William
    Centre for High Resolution Transmission Electron Microscopy, Department of Physics, Nelson Mandela University, 6031 Port Elizabeth, South Africa.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Öhman-Mägi, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Norgren, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Investigation of copper alloying in a TNTZ-Cux alloy2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 22, article id 3691Article in journal (Refereed)
    Abstract [en]

    Alloying copper into pure titanium has recently allowed the development of antibacterial alloys. The alloying of biocompatible elements (Nb, Ta and Zr) into pure titanium has also achieved higher strengths for a new alloy of Ti-1.6 wt.% Nb-10 wt.% Ta-1.7 wt.% Zr (TNTZ), where strength was closer to Ti-6Al-4V and higher than grade 4 titanium. In the present study, as a first step towards development of a novel antibacterial material with higher strength, the existing TNTZ was alloyed with copper to investigate the resultant microstructural changes and properties. The initial design and modelling of the alloy system was performed using the calculation of phase diagrams (CALPHAD) methods, to predict the phase transformations in the alloy. Following predictions, the alloys were produced using arc melting with appropriate heat treatments. The alloys were characterized using energy dispersive X-ray spectroscopy in scanning transmission electron microscopy (STEM-EDS) with transmission Kikuchi diffraction (TKD). The manufactured alloys had a three-phased crystal structure that was found in the alloys with 3 wt.% Cu and higher, in line with the modelled alloy predictions. The phases included the α-Ti (HCP-Ti) with some Ta present in the crystal, Ti2Cu, and a bright phase with Ti, Cu and Ta in the crystal. The Ti2Cu crystals tended to precipitate in the grain boundaries of the α-Ti phase and bright phase. The hardness of the alloys increased with increased Cu addition, as did the presence of the Ti2Cu phase. Further studies to optimize the alloy could result in a suitable material for dental implants.

  • 5. Magadla, Sive
    et al.
    Hashe, Nobom
    Fowler, Lee
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Neethling, Jan
    Microstructural characterisation and antibacterial properties of Ti-Cu alloys2019In: Metals in Medicine: F7:Surface modification, traditional and new alloys, permanent and resorbable metals, Stockholm, 2019Conference paper (Other academic)
    Abstract [en]

    Introduction/Purpose

    Ti-Cu alloys are promising alloys for biomedical application in dentistry. Previously, metal ions (Ag+ and Zn+) have been widely used as antibacterial agents, however these ions have been found to be toxic to the human body [1]. Copper has been preferred as a good antibacterial agent due to its low toxicity and high cytocompatibility. The current study is aimed at producing biocompatible Ti-Cu alloys with good mechanical properties, corrosion resistance and antibacterial properties.

    Methods

    Several TiCu alloys were synthesized with the following composition: Cp-Ti, Ti-0.88wt.%Cu, Ti-2.44wt.%Cu, Ti-3.24wt.%Cu and Ti-10wt.%Cu. The alloys were then exposed to staphylococcus epidermidis bacteria. Then they were characterized using the scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), scanning transmission electron microscopy (STEM), focused ion beam SEM (FIBSEM) and transmission Kikuchi diffraction (TKD) technique.

    Results

    Figure 1(c) and (f) are the typical SEM micrographs of Ti-3.24wt.%Cu showing the regions of low and high bacteria on the surface of the alloy. FIBSEM samples were cut from the low and high bacteria regions for the TEM and the TKD analysis. A typical bright field STEM image (Fig1(b)) of the lower bacteria region revealed that there were Cu particles (bright) and the Ti phase (grey). The Cu particles seem to sit on the surface area of the lower bacteria region. The TKD confirmed the presence of alpha Ti phase and copper (Fig1a). Figure 1 (e) is a typical bright field STEM image of high bacteria region showing a continuous Cu layer (bright) and a Ti phase. The TKD revealed the presence of Ti alpha phase and Ti2Cu phase.

    Conclusions

    Compared to CP-Ti (not included here), SEM results on Ti-Cu alloys show that Cu does have antibacterial properties and Ti2Cu phase has been observed only on the high bacteria region of the Ti-3.24wt.%Cu alloy.

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