The 2018 MRS Spring Meeting & Exhibit came to a successful conclusion on Friday, April 6, with over 4,000 attendees. Our congratulations go to the Meeting Chairs Edward Botchwey, Catherine Dubourdieu, Quanxi Jia, Shane Kennett, and Cheolmin Park for putting together an excellent technical program along with various special events. MRS would also like to thank all the Symposium Organizers, Session Chairs, and Symposium Assistants for their part in the success of this meeting. We also thank our Sponsors and Exhibitors.
Contributors to news on the 2018 MRS Spring Meeting & Exhibit include Meeting Scene reporters Maria Torres Arango, Antonio Cruz, Dale Karas, Judy Meiksin (@Judy_Meiksin), Don Monroe, Ashley White, Frieda Wiley (@Frieda_Wiley), and Lori Wilson; with photographer Rebecca Tokarczyk; newsletter production by Erin Hasinger and Joe Yzquierdo; Bloggers Matthew Diasio (@MatSciMatt), Araceli Hernández-Granados (@AraceliHG02), and Jiajia Lin; and with assistance from Michael Moran.
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Highlights of the Friday morning session
Written by Antonio Cruz
Sometimes science needs to take risks, motivated by pure discovery rather than by the promise of technological applications. The National Science Foundation is one of the most prominent US government organizations that provides funding for such risks. The Friday morning session on “Enabling Quantum Leap—Braiding and Fusing Majoranas,” researchers presented some of their results studying Majorana modes. Eric Rowell from Texas A&M University described his work developing mathematical models of anyons, of which Majorana fermions are a type. Other researchers discussed their difficulties and successes in studying braiding of Majorana fermions, where in space the modes are located, and devices that exploit them. Sergey Frolov of the University of Pittsburgh concluded the session, and remarked that braiding is a difficult experiment, and all current proposed schemes are “crazy.” This work lies at the intersection of disparate fields—materials science, mathematics, physics—and it will take everyone working together to study it effectively.
Ethel Koranteng, University College London
Light-Activated Surfaces for Reducing Hospital Acquired Infections
Written by Maria Torres Arango
Reducing the impact of hospital acquired infections (HAIs) represents a huge challenge for the healthcare sector due to the increasing antimicrobial resistance developed by bacterial populations in hospital environments, costing billions and affecting patients and medical personnel. This problem has been identified to be a consequence of excessive and sometimes unnecessary use of antibiotics. Luckily, innovative efforts to address this issue seem to become increasingly feasible from the antibacterial activity of quantum dots (QD) when exposed to light. Ethel Koranteng from University College London shared their efforts to develop antibiotic-free disinfecting agents based on the synergistic effect of newly available non-toxic cadmium-free QD and crystal violet. As Koranteng mentioned in her talk, this combination enables the use of a wider range of the visible-light spectrum to maximize the antibacterial activity, resulting in efficacies of 99.99% and 99.97% in killing laboratory strains of Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA), respectively.
First Place Winners:
Yadong Yin, Plum Flower
Magali Ferro, Life Was Growing Everywhere
Peter Sherrell, Nanosucculents
Second Place Winners:
Xin Zhang, ZnO Particle Carbonation
Kanit Hantanasirisakul, Deep Sea Fish
Jonathan Major, Antimony Selenide Dendritic Micro Trees
Alex Ganose, University College London
Zachary Hood, Georgia Institute of Technology
Zhiyuan Liu, Nanyang Technological University
Seongjun Park, Massachusetts Institute of Technology
Ottman Tertuliano, California Institute of Technology *Nowick
Hsinhan Tsai, Rice University
Ying Wang, University of California, Berkeley
Saien Xie, Cornell University
Renjie Chen, University of California, San Diego
Jonghyun Choi, University of Illinois at Urbana-Champaign
Zeyu Deng, University of Cambridge
Sreetosh Goswami, National University of Singapore
Bumjin Jang, ETH Zurich
Dohyung Kim, University of California, Berkeley
Shankar Lalitha Sridhar, University of Colorado Boulder
Dingchang Lin, Stanford University
Xiaolong Liu, Northwestern University
Erfan Mohammadi, University of Illinois at Urbana-Champaign
Hongjie Peng, Tsinghua University
Sean Rodrigues, Georgia Institute of Technology
Michael Cai Wang, University of Illinois at Urbana-Champaign
Xiaoxue Wang, Massachusetts Institute of Technology
Shuai Yuan, Texas A&M University
Hyunwoo Yuk, Massachusetts Institute of Technology
Written by Don Monroe
In his talk about the work that led to his Mid-Career Researcher Award, David Mooney of Harvard University described “mechanoregeneration: the idea of mechanical signals controlling the regeneration of tissues and organs in the body.” In addition to fundamental experiments, he showed how these insights are leading to therapeutic devices.
There is growing recognition that cells respond not only to chemical signals but to mechanical cues. These can be either responses of the surrounding materials to forces the cells generate or externally imposed forces. “Materials can be used to control these mechanical signals,” Mooney said.
Mooney’s team has exploited three-dimensional (3D) alginate hydrogels, which are block-copolymer polysaccharides. Crosslinking occurs between one type of block, but not the other, letting the researchers tune the stiffness to see its effect on stem-cell proliferation, migration, and differentiation. Unlike other systems, “the architecture and the macromolecular transport in these gels does not change as we vary the extent of crosslinking,” Mooney stressed. In addition, cells do not adhere to the underlying gel backbone, but only to small synthetic peptides that the researchers covalently attach.
Experiments “demonstrated unequivocally in 3D that we could control the fate of these cells simply by controlling the stiffness of the gel in which the cells were encapsulated,” Mooney said. For example, mesenchymal stem cells differentiated into fat cells in a soft matrix, but into bone-forming cells in a stiffer matrix.
Beyond the static stiffness, Mooney showed that “fundamental elements of cell biology were dramatically altered by the stress relaxation or viscoelasticity of these hydrogels.” Modifications of this relaxation by changing molecular weight and introducing PEG spacers changed the speed of bone regrowth, and modified the ability of the cells to remodel their matrix.
Clinical application of stem cells today, however, is dominated by IV infusion of individual cells, but almost all of the injected cells are gone within a day. This problem can be addressed by surgically implanting hydrogels, but Mooney illustrated a successful alternative in which the cells are individually embedded in hydrogel using droplet microfluidics. This results in better cell survival, and lets researchers use, for single cells, the gel-modification tricks developed for populations in culture.
Cells and tissue are sensitive not only to mechanical response to forces they generate, but to applied forces, Mooney illustrated for muscle tissue. This insight led to a project, spearheaded by Ellen Roche (now at the Massachusetts Institute of Technology) to develop pneumatically actuated soft-robotic devices to assist heart function and regeneration.
The envisioned device combines two capabilities. First, a mechanical sleeve around the heart provides extra pumping assistance without directly contacting the blood. The team showed that this device significantly enhanced cardiac output in pigs. Second, therapies can be locally provided without additional surgery. This capability is especially important for cellular therapies, Mooney said, where single applications are often insufficient for regeneration.
In his final topic, Mooney described a key requirement for applying forces to tissues, which is adhesion to wet and dynamic tissues. Mooney, former colleague Jeong-Yun Sun, and their collaborators combined the ionically crosslinked polysaccharide network with a covalently crosslinked protein network. The hydrogel “crosslinks can dissipate energy, but the bonds are pretty weak,” Mooney noted. The covalent crosslinks are stronger, but the materials are brittle. The combination provides “an unprecedented level of toughness.” Combining this material with chemistry to bridge the underlying tissue and the hydrogel resulted in tough adhesives that “dramatically outperform anything that has been previously described,” including superglue, Mooney said.
The Mid-Career Researcher Award recognizes exceptional achievements in materials research made by mid-career professionals. The Mid-Career Researcher Award is made possible through an endowment established by MilliporeSigma (Sigma-Aldrich Materials Science). This year’s award was given “for pioneering contributions to the field of biomaterials, especially in the incorporation of biological design principles into materials and the use of biomaterials in mechanobiology, tissue engineering and therapeutics.”
Spencer Hawkins, Universal Technology Corporation, Air Force Research Laboratory (AFRL)
Understanding the Onset of Damage at the Nanoscale in Polyurethane Composites Containing Silver Nanoparticle-Coated Carbon Nanofiber
Xiaoming Zhao, Queen Mary University of London
Fullerene Single-Crystalline Nanostructures for Organic Electronics
Charles Fan, Albuquerque Academy, Angstrom Thin Film Technologies LLC
Hierarchical Biomimetic Nanostructures for Oxygen Membranes
Shayak Samaddar, Purdue University
Bladder Tumor Targeted Cyclic di-GMP Liposomes
Holly Golecki, The Haverford School
Design and Characterization of Edible Soft Robotic 'Candy' Actuators
Written by Frieda Wiley
Julia Glaum, Norwegian University of Science and Technology
Piezoelectric Performance and Cytotoxicity of Porous, Barium-Titanate-Based Ceramics for Biomedical Applications
Piezoelectric effect is a terminology that defines the ability of certain substances, such as ceramics, bone, DNA, and crystals, to generate alternating current charges. Researchers are investigating this property as it relates not only to piezoelectric performance, but also cytoxicity of porous barium titanate-based ceramic for biochemical applications.
Successful tissue integration has some unusual requirements, including liquid stability. Direct piezoeffect results from mechanical stress while indirectly the vibration produced by mechanical force yields a piezoelectric effect. These are two different triggers in tissue repair.
Medical ultrasound, in vivo sensing and in vivo synergy harvesting, and tissue repair mimic the stress-generated potentials in bones. The motivation of the study is to explore the topic of tissue implant materials to improve the bonding between the artificial implant and the bone.
Researchers used corn starch and poly(methylmethacrylate) (PMMA) to form the artificial template. The strength and polymerization of materials comprised of BaTiO3 can be measured; such compounds are stable up to 35% porosity; after this point, a loss of D33 cells occurs due to an unpoled matrix. A decrease in D33 is also observed as porosity increases due to the formation of air bubbles in the matrix.
Different pore formers lead to similar porosity; both corn starch and PMMA exhibited similar porosities. Additionally, cytotoxicity presents a major challenge. For example, it is easier to get more living cells on the ceramic sample than on the polystyrol. Despite numerous challenges faced with the development of different pore formers, cell proliferation and viability show promise. Leeching tests are forthcoming.