Day 2 :
Keynote Forum
Bernhard Mingler
Austrian Institute of Technology GmbH, Austria
Keynote: Biomaterials with unique properties for implant applications
Time : 10:00-10:30
Biography:
B Mingler studied physics at the University of Vienna, where he also worked and taught as Assistant Professor mainly in the field of Materials Science. Since 2009 he works at the Austrian Institute of Technology GmbH in the Center for Health & Bioresources. In his function as Senior Scientist and Thematic Coordinator he has his expertise in design and application of biocompatible and biodegradable metals and alloys, their characterization in respect of microstructure, mechanical, corrosive and biological properties as well as in theory and implementation of severe plastic deformation (ECAP, HPT) and characterization of ultrafine grained and nanocrystalline materials. He was the Project Manager of several contract research projects and funded projects and currently heads Research Studio Austria and the strategic lead project. He is co-inventor of several patents dealing with special Mg alloys and ECAP designs and applications.
Abstract:
Equal Channel Angular Pressing (ECAP) is an innovative processing technology for the production of metallic biomaterials with unique properties. It leads to a strong grain refinement of bulk crystalline materials down to the sub-micrometer range by means of very large, multidimensional plastic deformation under enhanced hydrostatic pressure. The modified microstructure of ECAP-processed biomaterials is the reason for high strength combined with good ductility. Such high-performance biomaterials are very promising candidates for applications in high-loaded implants, for longer implant lifespans, for the miniaturization of implants and for completely new implant concepts. The effects of ECAP are presented on the examples of commercially pure (CP)-titanium and special Mg-alloys. CP-Ti is a commonly used implant material especially in dentistry. In this field of application, the Ti-alloy Ti6Al4V-ELI is avoided because of its problematic alloying elements aluminum and vanadium. Nevertheless, for many dental applications a higher strength than that of CP-Ti is requested. Using ECAP and tailored optional post-processing we achieved in CP-Ti ultimate tensile strengths >1000 MPa, which is stronger than the Ti-alloy. A further very important effect of ECAP is that it produces a very homogeneous ultrafine grain structure and consequently very homogeneous mechanical property across the whole work piece. The ideal material for biodegradable implants must combine high biocompatibility, application-oriented degradation rate and excellent mechanical properties especially for load bearing applications. To achieve all these goals, we used a newly developed double-ECAP tool to process a special low alloyed Mg alloy which was developed and produced at AIT. The double-ECAP tool consists of three channels with two intersection angles and offers exceptional high deformation efficiency. By using it, the ultimate tensile strength of a ZX00 Mg alloy could be raised to unprecedented strength values of about 400 MPa.
Keynote Forum
Helen Reveron
INSA de Lyon - Univ Lyon, France
Keynote: Mechanical properties of new zirconia-based bioceramics with a metal-like behaviour
Time : 11:15-11:45
Biography:
Helen Reveron is a Research Scientist at the French National Center for Scientific Research (CNRS). Since 2006, she works at the MATEIS Laboratory of INSA-Lyon in the development and characterization of ceramic nanocomposites with controlled micro-nanostructures. Before coming to Lyon, she earned an Engineer’s Degree in Materials Science from USB-Caracas-Venezuela (1996) and a PhD in Ceramics and Surface Thermal Treatments from ENSCI-Limoges-France (2000). She then worked as Assistant Professor (Materials Science Department, USB-Caracas) and was interested in the hydrothermal synthesis of oxide nanoparticles, before coming-back to France in 2003. For 3 years, she worked at the ICMCB-CNRS (Chemical Institute of Condensed Matter, Bordeaux, France) in the continuous supercritical synthesis of ferroelectric nanoparticles and the processing/characterization of nanostructured ceramics obtained through SPS (Spark Plasma Sintering). She is the author of more than 35 papers and 5 patents.
Abstract:
Yttria-stabilized (Y-TZP) zirconia ceramics are increasingly used for developing metal-free restorations and are now considered as promising alternatives to titanium as dental implants. Zirconia indeed possesses high strength and good toughness for a ceramic, together with excellent bio-integration, biocompatibility and translucency. However, Y-TZP ceramics are still considered as brittle ceramics, since transformation induced toughening occurs after cracks start to propagate. Moreover, Y-TZP can undergo low temperature degradation (LTD) or ageing, leading to a loss of strength and micro-cracking. Therefore, our current research is focusing on strategies to develop alternative zirconia-based materials with better stability in-vivo and higher degree of ductility, especially for dental implants applications in which the translucency is less important but for which a perfect stability, good mechanical properties and long lifetime should be ensured. In this work the mechanical characterization of a new type of very-stable zirconia-based composites is presented. These materials are composed of ceria-stabilized zirconia (Ce-TZP) and two second-phases (alumina and strontium aluminate) and can exhibit very high strength, toughness and ductility. In other words, in these ceramics, plastic deformation occurs before failure driven by the tetragonal (t) to monoclinic (m) zirconia phase transformation, which leads to mechanical behavior laws similar to metals. During the oral presentation, the effect of the composition and/or the microstructure on the strength-toughness relationship will be presented and the validity of various mechanical tests used to measure the fracture strength on these materials discussed.
- Sessions: Dental Biomaterials | Biomaterials Applications | Properties of Biomaterials
Location: Bismarck
Chair
Vanja Kokol
University of Maribor, Slovenia
Session Introduction
Vanja Kokol
University of Maribor, Slovenia
Title: Biomimetic gelatine coating for less-biodegradable and surface bioactive Mg alloys
Biography:
Assoc. Prof. Vanja Kokol PhD got a PhD in area of Textile chemistry in 2001 at University of Maribor, Faculty of Mechanical Engineering (UM-FS). She have been employed at UM-FS from 1994, currently as a research counsellor with the habilitation of Assoc. Prof.. Her research work in the last decade is oriented in modification and functionalization of fibers and biopolymers, and their processing in highly-engineered materials for different applications (from technical to biomedical). Special attention is attributed to the development of biopolymeric 2D and 3D materials with targeted and biocompatible antimicrobial activity. She is author of more than 90 papers, 3 book chapters, 3 patents, was supervisor of several (seven) doctoral and post-doctoral (five) students, and have been active in research programme Textile chemistry (from 1999) and Center of Excelence (from 2010) for advanced materials and technologies, area of Soft biomaterials. She was involved (leading or collaborating) in many national (ARRS-L2-7576, ARRS-J2-7018), bilateral (SLo-CZ, Slo-IT, SLO-IND, SLO-DE), international (E!3100 CAWAB, E!3654 BIOPOLS, EraNet Manunet NANOWEL, EraNet Matera Plus ANTIMICROB PEPTIDES, E!4956 MAGNET, EraNet MNT TABANA, EraNet MNT n-POSSCOG) and EU (H2020-PILOTS-03-2017-760601-2-NanoTexSurf, FP7-NMP-2011-SMALL-5-280519-NANOSELECT, FP7-NMP-2011-LARGE-5-280759-NANOBARRIER, Erasmus-Mundus (EMA2)-2013–2540/001–EUPHRATES, Marie Curie ToK/DEV FP6-MTKD-CT-2005-029540-POLYSURF, FP6-2004-SME-COOP-032877-ENZUP) funded research projects.
Abstract:
Magnesium (Mg) alloys have emerged as innovative orthopaedic implant materials due to their excellent degradability, which eliminates the need for a second surgery for their removal. However, rapid degradation of Mg alloys and subsequent loss of mechanical integrity before the tissue regeneration limits their application. The Mg-4Ag and Mg-5Gd binary alloys` degradation and corrosion properties were studied under in vitro conditions (in a simulated body fluid solution of pH 7.4 at 37°C) by using various analytical techniques and time-frame windows (up to 3 vs. 28 days), and compared with the pure (99.9 wt%) Mg alloy, before and after a biomimetic gelatin (GEL) coating via dopamine. Different kinetics and mechanisms of the alloys` degradation were identified, influencing their corrosion rates` dynamics. The EIS measurements of uncoated alloys, being performed for up to 3 days, revealed that the corrosion of all three alloys are under a kinetic-controlled mechanism, among which only pure Mg and Mg-4Ag show a repassivation ability in this time-frame. However, the corrosion rates of binary alloys were lower, reaching a value of around 0.33 mm/y and a release of 64 mg/L Mg2+ ions after 28 days of incubation, that was accompanied by a lower pH change (up to pH 8.3), compared to the pure Mg alloy, getting additionally reduced by GEL coating. The spectroscopic (FTIR, XRD, EDXS) and microscopic (SEM) studies revealed the formation of MgO products, as well as apatite formation on the pure Mg alloy surface, while thick and homogenous layers of differently-shaped and chemically secondary-phased Mg(OH)2 products were identified on both binary alloys after 28 days. Besides, a protective interface layer between the alloy surface and SBF solution was formed on GEL-coated alloys, which further stimulates the mineralization of calcium phosphate compounds, being patterned by GEL macromolecules conformation. Among the binary alloys tested, the Mg-4Ag alloy seems to be the most appropriate biomaterial regarding the in-vitro degradation process that would lead to a suitable healing process at the implantation site, compared to the others available from the literature.
Jozsef Bako
University of Debrecen, Hungary
Title: Biodegradable polymer based electrospun nanofibers for dental applications
Biography:
Jozsef Bako has his expertise in nanostructured photopolymerisable polymer system fabrications and evaluations. The main research field are the biodegradable polymer based hydrogel, nanogels and nanofibers as drug delivery systems. The research fields are connecting to scaffold creation for tissue regeneration aims by 3D printing methods, and production of different inorganic/organic composites and nanofibers by electrospinning technique.
Abstract:
Electrospinning is a versatile method for fabrication of submicron sized fibers from biopolymers, ceramics and composite materials. The dental application possibilities of these nanofibers are intensively research areas on the fields of tooth or pulp regenerations, prevention of dental caries, or drug delivery systems. Biopolymers can facilitate the elasticity of created structures, and ensure the similarities to the extracellular matrix. The tailoring of the diameters of the fibers, and pore sizes of the structures ensures the optimal conditions for the proliferation and differentiation of cells. The delivery of biological active ingredients, factors, or drugs can achieve fast and supported regeneration. Composite materials give possibly of adjusting physical, biological, or release properties. Nanofibers combined with inorganic ceramics, or polymers with nanoparticles can create functional materials for the speed up wound healing, or osseointegration processes.
Polymer solutions were created for electrospinning process from Poly-vinyl-alcohol (18-88 Ph, Eur.Merc) (PVA) in 10 w/w% and 50% precrosslinked, and 50% methacrylated-poly-γ-glutamic acid nanoparticles (MPGA-NP) in 15w/w%. Irgacure 2959 1w/w% was added to the composite as photoinitiator. Nanofiber fabrication was performed by Nanospinner NS1 electrospinning device (Inovenso). The created fiber matts were phtopolymerized by Bluehase 20i (Ivoclar Vivadent) dental lamp for 60sec, and the biocompatibility properties was investigated by SAOS-2.
The diameters of created MPGA/PVA nanofibers were between 82.1-149.2 nm with the average of 120.7±17.5 nm. The crosslinking of the fibers by post photopolymerization was successful, and the fibers not dissolved during the one week cell proliferating test. The good biocompatibility of the created electrospun nanofibers was proved by the presence and proliferation of SAOS cells.
This nanoparticles in the nanofibers construction allow and enhance the control of different drug releases. The work is supported by the GINOP-2.3.2-15--2016-00011 and GINOP-2.3.2-15-2016-00022.. project. The project is co-financed by the European Union and the European Regional Development Fund.
Tae-il Son
Chung-Ang University, Republic of South Korea
Title: Stabilization of protein–drugs (EGF/TGF- β/Bmp-2) by photoreactive natural polymer
Biography:
Tae-il Son was awarded the degree of PhD by Tokyo Institute of Technology, Japan in 1989. He is a Professor in the Department of Systems Biotechnology, Chung-Ang University and a Visiting Scholar at RIKEN (2007). He has served as President of the Korean Society for Chitin and Chitosan. He is currently the Director of Biomaterial Field in the Korean Society of Industrial and Engineering Chemistry (KSIEC) in Korea. He has published more than 100 papers in reputed journals.
Abstract:
Bioactive molecules such as EGF, TGF-β, BMP-2, are very important and useful materials in medical field; regenerative medicine and pharmacy. Immobilization method is one of current researching to overcome low stability and high cost of bioactive molecules. Chemical methods have been used widely for immobilization of bioactive molecules. However, there are some of drawbacks with this method. For example, chemical method may produce potential toxic by-product, and, in case of physical method, low efficiency of immobilized bioactive material is observed. To solve these problems, recently, the immobilization by photo-immobilization has been researched widely. The advantages of photo-immobilization are 1) high selectivity of chemical reactions or processes under mild conditions (ambient temperature of also much below), 2) typically no need for added catalysts or special solvents, 3) spatially addressable effects (2D and 3D structuring possible) and 4) applicable to very small and (relatively) large scales. To use for photo-immobilization, various natural polymers, such as gelatin, chitosan, hyaluronic acid reacted by irradiation to UV or visible light can be applied for medical area to increase biocompatibility and functionality, for example, coating agent for bioinert devices like stent and implant, anti-adhesive agent, wound dressing and bio-adhesive.
Giuseppe Tronci
University of Leeds, UK
Title: Photoactive type I (atelo) collagen as building block of advanced wound dressings
Biography:
Giuseppe Tronci is a Lecturer in Healthcare Materials at the University of Leeds with leading expertise in the chemistry of biopolymers, design of integrated biomimetic systems, and high-value manufacture of medical devices. He has established a bespoke platform for the fabrication of customised collagen materials with retained triple helix conformation and multiple integrated biofunctionalities. This work has led to the development of a University of Leeds patent-pending technology, whose applicability in wound healing has been successfully confirmed in diabetic mice.
Abstract:
The trends in diabetic occurrence and aging populations impose a heavy economic burden on healthcare providers worldwide [1]. Diabetic wounds suffer from delayed healing, and can soon become infected, chronic ulcers. If not treated timely, they can lead to gangrene, haemorrhage and lower-extremity amputations, potentially resulting in permanent disabilities and pain for patients. Advanced wound dressings have been commercialized to respond to the pressing needs of an increasing diabetic population. However, control of the wound microenvironment and matrix metalloproteinase (MMP) activity is still only partially accomplished, resulting in economically unaffordable healing times. Here, type I photoactive (atelo)collagen was synthesized and explored as a building block of factor-free advanced wound dressings with customisable macroscopic properties and integrated wound-regulating functionalities. Covalent functionalization of rat tail collagen with photoactive compounds, e.g. 4-vinylbenzyl chloride, was initially confirmed (by 1H-NMR, TNBS colorimetric assay, and circular dichroism) to prompt the synthesis of UV-induced networks of collagen triple helices [2, 3]. The type and degree of collagen functionalization governed the structure-property relationships, whereby the averaged swelling ratios (SR: 707-1600 wt.%), bulk compressive (Ec: 15-129 kPa) and atomic force microscopy (AFM) elastic moduli (EAFM: 16-387 kPa) could be adjusted [4]. Obtained network configurations proved key to control the activity of MMP-9 in vitro, with respect to a leading dressing product. This synthetic route was successfully transferred to minimally-antigenic, telopeptide-free type I collagen [5], resulting in comparable water-swollen atelocollagen networks. Preclinical investigations in a full-thickness wound model in diabetic mice proved the accelerated healing capability of this collagen system with respect to a commercial polyurethane dressing [6].
Susanne Staehlke
University of Rostock, Germany
Title: Intracellular calcium ion signaling dependent on surface properties of biomaterials
Biography:
Susanne Staehlke earned her Diploma in Genetic and Microbiology at the University of Rostock, and went on to earn her PhD at the University Medical Center Rostock, Dept of Cell Biology, Germany, studying the interaction of human osteoblasts with defined microtopographical features of titanium-cell architecture und signaling. She is now a young researcher completing her Post-doctoral training at the University Medical Center Rostock, Dept of Cell Biology. She is a Member of the German Society for Biomaterials (DGBM) and got DGBM Poster awards in 2011 and 2013. She is skilled in western blot analysis, immunofluorescence, biomedical science, flow cytometry, cell signaling and confocal microscopy. She has published over 10 papers and has given several invited presentations at international meetings around the world (Hong Kong: ICBB 2012, Minneapolis: BioInterface 2013, Oslo: ScSB 2013, Rytro: PSBM 2016 and 17, Xian: CMCB2017, Bordeaux: FiMPART 2017).
Abstract:
The first critical courses for assessing the suitability of a new biomaterial in medicine are biofunctionality and compatibility of the biosystem at the site of its effect. Topographical as well as chemical surface properties of biomaterials have a specific impact of integration and regeneration in bone tissue. The surface stimuli can affect the cell behavior, either detrimentally or favorably. So, the osteoblasts recognize their surrounding by adhesion receptors connected intracellularly with focal adhesion complexes. The associated intracellular actin cytoskeleton is in control for cell morphology, migration as well as for the transmission of signals and forces of the surroundings into the cells. External signals from physico-chemical environments finally influence the cell function (Figure 1). However, it is unclear as to which physiological processes will be affected in detail. In the previous studies, we could find out that defined geometrical micro-pillars influenced the cell architecture and the cell function of human MG-63 osteoblasts. In addition, the mobilization of intracellular calcium ions (Ca2+) after ATP stimulus was significantly impaired in cells growing on micro-pillars. It raises the question whether the mobilization of intracellular Ca2+, as “second messenger”, represents a sensitive parameter for in vitro studies of cell-biomaterial interactions. In our recent studies we examined the cell physiology and signaling on different chemical properties of biomaterials. The data indicate an increased intracellular Ca2+ signaling on plasma-chemically modified titanium with improved cell adhesion and spreading. The understanding of complex cellular behavior and intracellular signaling events is critical for the acceptance of new biomaterial surfaces in regenerative medicine.
Raisa Chetcuti
University of Malta, Malta
Title: Multi-layer PVD coatings for longer lasting orthopaedic implants: A tribocorrosion evaluation
Biography:
Raisa Chetcuti earned a B.Eng (Hons.) degree in Mechanical Engineering from the University of Malta in 2016. She is currently reading for an MSc in Mechanical Engineering at the same institution. Her research interests lie in the general field of biomaterials, but in her study, she is focusing on the tribocorrosion behaviour of PVD coatings to be applied to the artificial hip joint in conditions which replicate more closely the human body environment. In 2016, she has studied two novel PVD coatings for the bearings of the artificial hip joint and she was acknowledged with the best project in the mechanical engineering stream for 2016 award by the Chamber of Engineers in Malta.
Abstract:
Bone injuries coupled with a longer life expectancy necessitate the increased longevity of implanted biomaterials in patients suffering from bone diseases such as arthritis and osteoporosis. CoCrMo alloys have been widely employed as bearing surfaces in metal-on-metal (MoM) orthopaedic implants given their optimal mechanical properties and high corrosion resistance, as well as their relatively low wear rates and the post-operative stability. Loss of material by corrosion-wear of the hip joint and metal ion release into the blood stream are of prime concern as these can cause adverse reactions in the human body such as inflammation and bone erosion as well as loosening of the implant. This study aims to reduce the material loss at the bearing surfaces by the application of a multi-layer PVD coating on an ASTM F-1537 CoCrMo substrate. A 2.3 µm thick CrN coating was deposited on top of a 3.6 µm CoCrMo precipitate free supersaturated metastable solution of carbon, otherwise known as S-phase (S), by magnetron sputtered PVD. The coated samples designated as CrN/S, displayed a higher hardness and they retained their topography in nano-scratch tests relative to the uncoated CoCrMo substrate under the same conditions. Tribocorrosion tests for uncoated CoCrMo samples against uncoated CoCrMo counterfaces as well as for coated samples against coated counterfaces were conducted in Ringer’s solution as well as in diluted Foetal calf bovine serum at 37±1 °C under reciprocating sliding conditions. Results show that under all applied potentials and in both solutions, the coated tribopairs when compared to the uncoated ones exhibited a significant decrease in material loss and excellent resistance to catastrophic failure by tribocorrosion. Figure 1 outlines the improvement exhibited by the coated samples under anodic conditions; the coated samples exhibiting a smaller wear scar and mostly polishing wear as opposed to the uncoated samples, in both solutions.
David Sustr
Fraunhofer IZI-BB, Germany
Title: Assessment of Molecular Diffusion in Polyelectrolyte Multilayer Matrix
Biography:
David Sustr has an expertise in polyelectrolyte multilayers, diffusion measurements, microscopy techniques and more. He gained these abilities during studies and work at Masaryk University (Czechia), University of Helsinki (Finland), University of Potsdam (Germany), and Fraunhofer IZI-BB (Germany). His motivation comes from an interest in understanding reasons of behavior and its relationships of various systems and materials.
Abstract:
Assessment of molecular diffusion is of high importance in fields of drug delivery systems, biomaterial development, cell biology, etc. Assessment and comprehensive analysis of the diffusivity provides a deeper understanding of the diffusion phenomenon and heterogeneity of biomaterials. This insight eventually may lead to a rational control over the diffusivity. Fluorescence recovery after photobleaching (FRAP) is commonly employed to probe molecular diffusion by analysis of the recovery of fluorescence after photobleaching of fluorescently labelled molecules. Despite FRAP being a popular method, it is hard to analyze multi-fractional molecular diffusion due to limited possibilities of approaches for analysis. Here we present a novel simulation-optimization-based approach (S-approach) that significantly broadens possibilities of the analysis. In the S-approach, possible fluorescence recovery scenarios are primarily simulated and afterwards compared with a real measurement while optimizing parameters of a model until a sufficient match is achieved. This makes it possible to reveal multi-fractional molecular diffusion. The proposed S-approach is compared with a conventional, yet advanced analytical solution based approach (A-approach) which involves fitting an analytical solution of molecular diffusion to FRAP recovery profiles. The S-approach is superior for multi-fractional analysis compared to the analytical one, however, diffusion of a single population of molecules can be assessed by either of the approaches.
Eddy Eddy
Kyushu University, Japan
Title: Fabrication of calcium sulfate hemihydrate coated β-tricalcium phosphate through dissolution precipitation reaction
Biography:
Eddy Eddy is a dentist by training, graduated from Universitas Padjadjaran, Bandung, Indonesia in 2012. He continues his study as a PhD student in the Department of Biomaterials, Faculty of Dental Science in Kyushu University, Japan until present. His main research interest is the development and fabrication of artificial bone graft to fill defects in bones then afterwards replaced to new bone. He has presented his research at many international conferences.
Abstract:
Introduction: Previously, we had proposed that beta tricalcium phosphate granular cement (β-TCPGC) is useful to prevent flowing out of the β-TCP granules from the bone defect. When the β-TCP granules were mixed with acidic calcium phosphate solution, it set to form interconnected porous structure. Although it seems promising, β-TCP granules need to be mixed with the acidic calcium phosphate solution. Calcium sulfate hemihydrate (CSH) has self-setting ability by converting to calcium sulfate dihydrate (CSD) when exposed to water. Furthermore, CSD is the component of Osteoset®, which is a commercially available as a bone substitute. In this study, we fabricated CSH coated β-TCP granules through dissolution-precipitation method. This setting ability could inhibit the flowing out of the β-TCP granules from the bone defect.
Experimental Method: β-TCP granules were immersed in NaHSO4 solution for 1, 3, 5 and 7 days at 70oC. The samples were then heated at 120oC for 4 hours. β-TCPGC was prepared by mixing the granules with saline solution at a L/P ratio of 0:3 and identified by XRD and SEM. The mechanical strength of the β-TCPGC was measured as a DTS by universal testing machine. β-TCPGC was implanted in rabbit femur for 4 weeks and the percentage of newly formed bone was calculated from histological analysis.
Results: β-TCP granules immersed in NaHSO4 solution were coated by CSD and CSD became CSH after heating at 120ºC for 4 hours. CSH coated β-TCP granules mixed with saline solution were set and DTS value of β-TCPGC with 75 wt.% of CSH was 0.8±0.1 MPa. The percentage of newly formed bone of β-TCPGC with 75 wt.% of CSH was 28.7±0.5%. Meanwhile, β-TCP granules without coating were 19.9±1.1%.
Conclusion: CSH coated β-TCP were successfully fabricated and formed interconnected porous structure with good mechanical strength after mixing with saline solution.