Biodegradable Materials for Medical Applications II: Poster Session
Sponsored by: TMS Functional Materials Division, TMS: Biomaterials Committee
Program Organizers: Jaroslaw Drelich, Michigan Technological University; Ehsan Mostaed, Michigan Technological University; Malgorzata Sikora-Jasinska, Michigan Technological University; Jan-Marten Seitz, Syntellix AG; Petra Maier, University of Applied Sciences Stralsund; Norbert Hort, Helmholtz-Zentrum Hereon; Huinan Liu, University Of California Riverside
Monday 5:30 PM
February 24, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
Session Chair: Jaroslaw Drelich, Michigan Technological University; Ehsan Mostaed, Michigan Technological University; Malgorzata Sikora-Jasinska, Michigan Technological University; Jan-Marten Seitz, Syntellix AG; Petra Maier, University of Applied Sciences Stralsund; Norbert Hort, Helmholtz-Zentrum Geesthacht; Huinan Liu, University of California at Riverside
B-1: Bilayer Coated Magnesium Weaves as Degradable Bio-scaffolds: Ju Xue1; Cristina Romany1; Bowen Chen1; Lawrence Langan1; James Guest1; Timothy Weihs1; 1Johns Hopkins University
This study presents bio-degradable scaffolds that are 3D woven with magnesium (Mg) alloy wires and are coated with hydroxyapatite (HAp) and polycaprolactone (PCL) to improve bioactivity and structural integrity. The Mg wires have diameters of 200μm and 300μm and were woven into parts using a 3D weaving machine. The weaves were then electrochemically coated with HAp using an aqueous solution containing Ca(NO3)2 · 4H2O, NH4H2PO4 and NaNO3. The HAp coated weaves were then dipped into a PCL/ dichloromethane (DCM) solution using a custom-built dip coater. The concentration of the solution and the dip coating parameters were optimized to obtain a homogeneous, crack-free adhesive coating. The stiffness of the weaves were measured at each stage during the processes to evaluate the influence of each coating on structural integrity. The surface morphologies, phases, and thicknesses of the bilayer coatings were characterized with SEM/EDS, XRD, Raman spectroscopy and micro-CT.
B-3: Deformation Localization of Zn-Cu-Mn-Mg Alloys Designed for Bioresorbable Medical Implants: Morteza Shaker Ardakani1; Ehsan Mostaed1; Stephen Kampe1; Jaroslaw Drelich1; 1Michigan Technological University
Zinc and its alloys are a class of bioresorbable metals being investigated for medical implant applications. Despite some success in formulating alloys with desired strengths and ductility through compositional modifications and thermo-mechanical processing, some concerns remain regarding the deformation localization that undermines the creep resistance of these alloys. In this study, several Zn-xCu-yMn-0.05Mg alloys were formulated and their microstructures and tensile properties characterized after hot/cold rolling followed by annealing at a wide range of temperatures and times. Zn-1.0Cu-0.2Mn-0.05Mg alloy, in as-rolled condition, exhibited tensile strength and elongation of 393 MPa and 35%, respectively, along with a significant work softening behavior. Post-rolling annealing at 320℃ successfully suppresses the work softening behavior, but the tensile strength and elongation drop significantly to 233 MPa and 27%, respectively. The results indicate a change in deformation mechanism from phase/grain boundary sliding to dislocation slipping is responsible for the work hardening.
B-4: Discovery of Alloying Elements and Processing Parameters that Impart Improved Biocompatibility of Zinc-based Medical Implants: Lea Morath1; Alexander Oliver1; Katie Flom1; Roger Guillory1; Jeremy Goldman1; Eshan Mostaed1; Jaroslaw Drelich1; 1Michigan Technological University
Conventional metal stents remain in a treated artery for the lifetime of the patient. The permanent presence of foreign material is associated with harmful side effects. Bioresorbable stents that provide mechanical support during the healing phase and then harmlessly degrade may avoid the long term side effects. The interdisciplinary research team at Michigan Tech has been developing bioresorbable zinc alloys for stenting. An in vivo rat arterial implantation model was used to evaluate the biocompatibility of four new zinc alloys, two of which were thermal treated to improve structural characteristics. The explants were collected at six months, cryo-sectioned and histologically stained with H&E and VVG. Each cross section was measured for base neointimal length, protrusion of the implant into the lumen and neointimal area, metrics used to characterize the in vivo response. Results revealed favorable vascular responses to selected zinc alloys and thermal processing as compared to pure zinc.
Cancelled
B-5: Effect of Compressive Strain on Biodegradability in Pure Magnesium: Shun Yorifuji1; Naoko Ikeo1; Toshiji Mukai1; 1Kobe University
In recent years, development of biodegradable materials has been demanded. Magnesium is attracting attention a biodegradable material. Since degradation rate affects the deteriorating rate of mechanical properties, it’s necessary to control. Previous studies revealed that crystallographic orientation affects degradability of magnesium. Although formation of deformation twins is known as a dominant deformation mechanism accompanied with a large change in crystal orientation, the influence on the degradability has not been clarified yet.In this study, we investigated the effect of area fraction of {101 ̅2} tension twins on biodegradability. As a result, it was found that degradability is reduced by increasing area fraction of the twins. Besides, it was confirmed that the open circuit potential tends to increase lineally with the area fraction. These results suggested that the area fraction of deformation twin could control the degradation rate of pure magnesium.
B-6: Evaluation of Electrospinning Parameters for Fabrication of Biodegradable Drug Carrier Silk Fibers: Babak Jahani1; Sahar Tabatabaei2; Salimeh Yasaei Sekeh3; Long Jiang1; 1North Dakota State University; 2Pharmascience; 3University of Maine
Electrospinning is a standard and cost-effective method to produce fibers in the range of micrometer to nanometer. The main parameters affecting the morphology and diameters of electrospun fibers are viscosity and conductivity of solution, surface tension, applied voltage, tip to collector distance and the flow rate of solution from the needle tip to the collector. By tuning these parameters, electrospun fibers with desirable morphology and size can be achieved. In this study, silk fibers have been fabricated by electrospinning technique. Silk is a natural fiber contains two major proteins- hydrophobic fibroin and hydrophilic sericin. These fibers can be used as biocompatible and biodegradable drug carriers. The goal of this work is to experimentally evaluate the effect of each parameter of electrospinning process on the resultant electrospun fibers and also suggesting the optimized values for process parameters in order to satisfy the requirements of drug delivery applications.
B-8: Long Term Inflammatory Response to Zinc Materials in Murine Arteries: Alexander Oliver1; Roger Guillory1; Timothy Kolesar1; Lea Morath1; Katie Flom1; Ehsan Mostaed1; Jaroslaw Drelich1; Jeremy Goldman1; 1Michigan Technological University
Zinc alloys are under development for medical applications due to their degradation in physiological environment with nearly ideal in-vivo corrosion rate, suitable mechanical properties, and biocompatibility of corrosion by-products. However, the long-term neointimal inflammatory response and progression has yet to be characterized. Such details would make it possible to design zinc alloys with composition and surface finish that could alleviate potentially harmful inflammatory responses. In the present work, an immunofluorescence approach was used to measure the presence and distribution of conventional inflammatory markers (CD68, iNOS, and CD206) within the neointima surrounding murine arterial explants made of new zinc alloys at three, six, and eleven months post-implantation. We found a strong effect of alloying, processing and thermal treatment on the inflammatory response to arterial implants.
B-9: Mechanical and Wear Behaviour of Mg-Ca Alloys for Orthopaedic Implant Applications: Asmaa Elmaghraby1; Ahmed Aziz1; 1German University (GUC) in Cairo
The key concern facing the biodegradable Mg-Ca implant is the fast corrosion in the human environment. The ability to adjust degradation rate of Mg-Ca alloys is critical for the effective development of the biodegradable orthopaedic implants. This study focuses on the microstructure and mechanical properties including the wear rate and hardness test. The wear mechanism of Mg-Ca Alloys with Mg-0.1 Ca, Mg-0.3 Ca and Mg-0.51 Ca was discussed. Dry Sliding tests were performed on Mg-Ca Alloys using a pin on disc configuration, Wear Rates were measured within a load of 2 to 15 Newton and a constant sliding velocity of 250 rpm. Worn Surfaces were examined using a Scanning Electron Spectrometry (SEM). Three Wear Mechanisms were observed namely Abrasion, Oxidation and Plastic deformation have been observed.
B-10: New Approach in Development of Biodegradable FeMn Alloys: Crtomir Donik1; Irena Paulin1; Aleksandra Kocijan1; Matjaž Godec1; 1Institute of Metals and Technology
Biodegradable metals are bioactive materials with controlled temporary support function, that gradually degrade without a negative effect on the organism. They are suitable in specific areas of pediatrics, orthopedics and cardiovascular surgery. The properties of these materials are changed by combination of metallurgical, chemical and surface treatments. In Fe based alloys Mn is added in order to achieve the higher degradation rates and is the most appropriate alloying element for microstructural, corrosion, magnetic and toxicological properties. The goals of the current research are the synthesis of new Fe-Mn alloys. We tried to influence the formation of certain grain boundaries with the appropriate thermomechanical processes, chemical alloying thus enabling the precipitation of phases along the grain boundaries, simultaneously with the segregation of surface-active elements that will further increase corrosion rate. In addition to this approach, we are investigating changes of the surface with laser-texturing, thus accelerating the degradation of the material.
B-11: Novel Method for Increasing Mechanical Properties of Biodegradable Zinc: Anna Jarzebska1; Magdalena Bieda-Niemiec1; Łukasz Maj1; Martyna Strąg1; Daniel Wojtas2; Robert Chulist1; Jan Guśpiel1; Wacław Pachla3; Krzysztof Sztwiertnia1; 1Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Krako; 2AGH University of Science and Technology Faculty of Physics and Applied Computer Science; 3Institute of High Pressure Physics, Polish Academy of Sciences, Warszawa, Poland
Zinc seems to be the best candidate as material for producing biodegradable stents because of its optimal corrosion rate. The only limitation is low mechanical properties. In order to increase strength and ductility of zinc effect of cumulative hydrostatic extrusion and magnesium alloying up to 1.5 wt. % was proposed. To analysis the effect microstructure characterization via SEM/EBSD and TEM techniques was performed. Mechanical properties were established based on static tensile test. Influence of the method on corrosion rate was investigated by electrochemical and immersion tests. Subjecting low-alloyed zinc to hydrostatic extrusion gave great improvement in both strength and ductility, exceeding requirements for stents application. Such behavior can be ascribed to received unique microstructure resembling a composite composed of ultra-fine zinc’s grains bands alternately arrange with bands of refine to nanometer scale eutectic phase. Obtained results indicate that proposed method allows to gain excellent mechanical properties without deteriorating corrosion rate.
B-12: Research on Zn-Ag-Mg Alloy as a Potential Biodegradable Implant Material: Maria Watroba1; Wiktor Bednarczyk1; Jakub Kawałko1; Krzysztof Mech1; Gabriela Boelter2; Manuel Banzhaf2; Piotr Bała1; 1AGH University of Science and Technology; 2University of Birmingham
Biodegradable metallic materials with potential application as short-term implants have attracted great attention in recent years in the developing branch of biomaterials. Ease of manufacturing, optimal degradation rate, biocompatibility and lack of hydrogen gas evolution makes zinc a great competitor for magnesium- and iron-based alloys considered for these applications. Brittleness, poor mechanical strength, and recrystallization at room temperature of pure zinc created a challenge and the main goal of the research. The extensive SEM-EBSD and TEM microstructural characterization revealed that alloying with silver and magnesium additions and the use of plastic deformation processes resulted in grain refinement and formation of intermetallic phases, which contributed to relevant mechanical strength and ductility enhancement recorded during tensile tests. Precipitates occurring in the microstructures slightly accelerated degradation rate in static immersion test, in comparison to pure zinc. In the preliminary antibacterial test the formation of bacterial growth inhibition zone was observed around investigated samples.