Biological Materials Science: Biomaterials and Biomedical Applications
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Biomaterials Committee
Program Organizers: Po-Yu Chen, National Tsing Hua University; Francois Barthelat, McGill University; Michael Porter, Clemson University; Steven Naleway, University of Utah

Monday 2:00 PM
February 27, 2017
Room: Pacific 15
Location: Marriott Marquis Hotel

Session Chair: Francois Barthelat, McGill University; Benjamin Hatton, University of Toronto

2:00 PM  Keynote
Peptide-Enabled Materials & Systems for Technology & Medicine: Mehmet Sarikaya1; David Starkebaum1; Carolyn Gresswell1; Deniz Yucesoy1; Hanson Fong1; 1University of Washington
    Genetically Engineered Peptides for Inorganic solids (GEPI) are of a broad interest due to their capability for functionalization of solids and as molecular linkers, erector sets and assemblers as well as enzymes to synthesize solids in molecular technologies and nanomedicine. Refining combinatorial mutagenesis approaches (cell surface and phage display libraries) originally adapted from the principles of drug design, our laboratory has been experimentally selecting 100s of solid-binding peptides for a variety of metals, oxides, semiconductors, minerals, and 2D single layer materials. To acclerate directed evolution process, bioinformatics methods have been established for de novo designing multifunctional peptides in chimeric, modular constructs. Latest developments will be discussed in designing GEPIs with specific surface recognition and assembly characteristics augmented by computational modeling (MD and kMC) and present examples in quantum dot assembly on LED displays, graphene FET cancer biosensors, biofunctionalization of implants, and cell-free tissue reconstruction. Supported by NSF-DMREF and LSDF.

2:40 PM  
Nano- and Micro- scale Mechanical Properties of the Sclera following Proteoglycan Degradation: Zhuola Zhuola1; Riaz Akhtar1; Zhuo Chang1; 1University of Liverpool
    The mechanical properties of ocular tissues such as the sclera (white of the eye) have a major impact on the healthy function of the eye, and are governed by the properties and composition of the microstructural components. For example, biomechanical degradation associated with myopia occurs alongside a reduction of proteoglycans. Here, the role of proteoglycan degradation on the nano- and micromechanical properties of the porcine sclera is explored. In vitro enzymatic degradation of proteoglycans was conducted with α-amylase solution. Collagen fibril morphology and nanomechanical stiffness was measured with atomic force microscopy (AFM) and micromechanical properties with dynamic nanoindentation. The elastic modulus of the tissue was reduced in all α-amylase treated samples relative to controls. In addition, collagen fibril organisation was disrupted by proteoglycan depletion. Our data demonstrate that proteoglycans play an important role in determining not only the mechanical properties at these length scales but also collagen fibril arrangement.

3:00 PM  
Synthesis of Magnetic Nanoparticles as Effective Hyperthermia Agent: Jun Ding1; 1National University of Singapore
    Magnetic nanoparticles are promising for magnetic hyperthermia, which allows localized heating for cancer treatment. Many works have demonstrated the good hyperthermia performance against cancer after intratumoral injection. Our earlier work has demonstrated that magnetic nanorings and nanodiscs can have excellent hyperthermia performance. Our recent work has focused on the development of magnetic nanoparticles for intravenous injection. But, there are still technical challenges for practical applications, such as effective delivery with a substantial quantity in tumor and accurate in-vivo estimation of its concentration. In this work, we have prepared ultrafine Gd-doped Fe3O4 nanoparticles with a particle size of 4-5 nm. The presence of Gd enables us to estimate the distribution of these Gd-doped nanoparticles accurately after intravenous injection. Long blood circulation time has been obtained. Using MRI technique, T1-weighted image can be used for monitoring of distribution of magnetic nanoparticles.

3:20 PM  
Localized Nanomechancial Characterization of Arterial Stiffening in Human Arteries with the PeakForce Quantitative Nanomechanical Mapping Technique: Zhuo Chang1; Riaz Akhtar2; Maria Hansen3; Lars Rasmussen4; Po-Yu Chen5; Paolo Paoletti6; 1University of Liverpool; 2Centre for Materials and Structures, School of Engineering, University of Liverpool; 3Department of Cardiothoracic and Vascular Surgery, Odense University Hospital; 4Department of Clinical Biochemistry and Pharmacology, Centre of Individuakized Mmedicine In Arterial Diseases, Odense University Hospital; 5Department of Materials Science and Engineering, National Tsing Hua University; 6Centre for Engineering Dynamics, School of Engineering, University of Liverpool
    Arterial stiffening occurs with age and is highly related to cardiovascular diseases. However, nano-scale alterations due to arterial stiffening are not well understood. Here, we utilized the atomic forice microscopy (AFM) PeakForce Quantitative Nanomechanical Mapping (PF-QNM) mode. PF-QNM allows visualization of both surface topography and mechanical properties. We characterized nanomechanical properties of different layers in internal mammary arteries (IMA) from patents with high and low pulse wave velocity (PWV), an in vivo measure of arterial stiffness, in air and liquid. Overall, the dry samples were stiffer overall in the high PWV group (Low; 2038.7 ± 60 MPa, High; 2301.6 ± 48 MPa) (p < 0.0001), and in each layer. In hydrated samples, the medial layer was significantly stiffer in the high PWV group (Low; 228.4 ± 15.6 kPa, High; 735.8 ± 108.8 kPa) (p < 0.0001). Our nanomechanical results associate with PWV data and provide new insight into arterial stiffening.

3:40 PM Break

3:50 PM  Invited
Engineering Antibacterial and Anti-Biofilm Surfaces: Dalal Asker1; Benjamin Hatton2; 1University of Toronto; Alexandria University; 2University of Toronto
    Implanted medical devices are at significant risk of developing bacterial biofilm-associated infections and 60% of hospital-acquired infections are due to such biofilm formation. Herein we will present three complementary approaches to engineering surfaces to prevent bacterial attachment and biofilm formation, from highly strain specific to very general. Recently we have immobilized an glycoside hydrolase enzyme which rapidly degrades the extracellular polysaccharide (Psl) of P. aeruginosa and interferes with biofilm development. In a second approach, we have incorporated a common antimicrobial drug with surfactant-like properties into supramolecular drug/silica mesostructures through molecular self-assembly. Finally, we have demonstrated that PDMS elastomers infused with non-crosslinked PDMS polymer, can exhibit self-lubricated properties as a ‘slippery liquid infused porous surface’ (SLIPS), similar to many natural non-adhesive surfaces. These layers show a dynamic and continuous migration of the oil to the elastomer surface, which maintains a consistent surface liquid layer as a barrier to bacterial attachment.

4:20 PM  
Development of Sponge Structure and Casting Conditions for Absorbable Magnesium Bone Implants: Stefan Julmi1; Christian Klose1; Ann-Kathrin Krüger1; Peter Wriggers1; Hans Jürgen Maier1; 1Leibnitz Universitaet Hannover
    In the case of bone defects, there are two different methods to close such defects. One option is to use bone autografts, but therefore the bone graft has to be cut off from the same person’s hip. In this case the patient has to undergo an additional surgery, which bears complications, like causing inflammations. Absorbable, open-pored implants minimizes these risks. Synthetic bone implants are typically made of ceramic, bioglass or polymers. In this study, magnesium alloys are investigated as absorbable porous bone substitute materials in which the bone can grow into. The main advantages are the design flexibility to cast individual implants by investment casting and mechanical properties similar to the bone. Moreover, to meet the mechanical requirements, simulations of the sponge structure and compression tests are applied. In order to adapt the degradation behavior to the bone’s ingrowth behavior, the implant material has to be alloyed and coated.

4:40 PM  
Wet-lay Textile Technique for Biological Fiber Reinforced Hydrogel Scaffolds: Andrew Wood1; Vinoy Thomas1; 1University of Alabama at Birmingham
    Chemical crosslinking forms strong inter-polymer bonds in hydrogels but typically uses reagents that are cytotoxic while physical crosslinking is more temperamental to environmental changes but can be formed without these toxic reagents. In this study, we added a biological fiber-reinforcement phase to a hydrogel, poly(vinyl alcohol), formed through successive freezing-thawing cycles by incorporating a non-woven soy-fiber mat formed by the wet-lay process. By reinforcing the hydrogel with a wet-laid fibrous mat, the mechanical properties have increased. The soy fibers were also found to be cytocompatible with endothelial cell viability showing around 96.51% after a 48 h. This novel approach to hydrogel-reinforcement presents a rapid, tunable method by which hydrogels can attain increased mechanical properties without sacrificing their inherent biologically favorable properties.

5:00 PM  
Mechanical Properties of Synthetic Bone and Tissue Simulants: Andrew Brown1; Juan Pablo Escobedo-Diaz1; Paul Hazell1; 1UNSW Australia
    Traumatic brain injury (TBI) has had increased exposure as a public health safety issue over the past decade. At the forefront are the increasing number of returning servicemen and women from armed conflicts and athletes of all skill levels of various sports suffering from concussions. Sylgard 527 A&B gel and Synbone AG products have become increasingly used for biomedical studies, from fueling constitutive models to forensic case studies. Although Sylgard is a well-known brain simulant, scarce quantitative data exists for “off the shelf” bone and skin simulants. A polyurethane-based bone simulant from Synbone was subjected to quasi-static tensile and compression tests, hardness measurements, and three-point-bend tests. Similar testing was performed on a rubbery silicon skin simulant by the same manufacturer. A synthetic headform system was developed and subjected to various loading conditions to determine if the stiffness and load bearing capabilities reflect that of the human analogue.

5:20 PM  
Design of Novel Low-Ni Shape Memory Alloys for Biomedical Applications: Dana Frankel1; Ida Berglund1; Weiwei Zhang1; Nicholas Hatcher1; Jason Sebastian1; Gregory Olson2; 1QuesTek Innovations LLC; 2Northwestern University
    The development of non-surgical transcatheter aortic valve implantation (TAVI) techniques, which utilize collapsible artificial heart valves with shape memory alloy (SMA)-based frames, pushes performance requirements for biomedical SMAs beyond those for well-established vascular stent applications. The necessity for longer device lifetimes and smaller crossing profiles motivates the need for high-strength, fatigue-resistant structural frame materials. High rates of Ni-hypersensitivity raise biocompatibility concerns, driving the development of low-Ni and Ni-free SMAs for valve frame applications. In vitro studies using human mesenchymal stem cells show improved cell viability in the presence of PdTi-based SMAs compared to NiTi. Controlled precipitation of nanoscale, low-misfit, L21 Heusler aluminides can provide effective strengthening. In the current work phase relations, Heusler precipitation kinetics, superelastic properties, cyclic stability, and mechanical properties are characterized in various low-Ni and Ni-free (Ni,Pd,Fe)(Ti,Zr,Al) systems. Ongoing work focuses on expanding integrated computational materials engineering (ICME)-based process-structure-property models into Pt-containing systems.