Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session C45: Focus Session: Physics of Biomineralization |
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Sponsoring Units: DBIO DMP Chair: Pupa Gilbert, University of Wisconsin at Madison Room: Hilton Baltimore Holiday Ballroom 4 |
Monday, March 18, 2013 2:30PM - 3:06PM |
C45.00001: Gradual ordering in mollusk shell nacre: theoretical modeling and experimental results Invited Speaker: Susan N. Coppersmith Biominerals have attracted the attention of materials scientists, biologists, and mineralogists as well as physicists~because of their remarkable mechanical properties and incompletely elucidated formation mechanisms. Nacre, or mother-of-pearl, is a layered biomineral composite that is widely studied because of its self-assembled, efficient and accurately ordered architecture results in remarkable resistance to fracture. New experimental tools enable us to obtain new information about the organization and structure of the mineral~tablets in nacre. Our experimental and theoretical investigations yield strong evidence that orientational ordering~of these tablets is the result of dynamical self-organization. [Preview Abstract] |
Monday, March 18, 2013 3:06PM - 3:18PM |
C45.00002: Structural and Optical Analysis of the Bio-mineralized Photonic Structures in the Shell of the Blue- Rayed Limpet \textit{Ansates Pellucida} Mathias Kolle, Ling Li, Stefan Kolle, James Weaver, Christine Ortiz, Joanna Aizenberg Many terrestrial biological organisms have evolved a variety of micro- and nanostructures that provide unique optical signatures including distinctive, dynamic coloration, high reflectivity or superior whiteness. Recently, photonic structures have also been found in the shells or spines of marine animals. Life under water imposes very distinct constraints on organisms relying on visual communication and on the designs and the materials involved in aquatic photonic structures. Here, we present a bio-mineralized calcium carbonate - based crystalline photonic system buried in the shell of the blue-rayed limpet \textit{Ansates pellucida}. The structure consists of a layered stack of calcite lamellae with uniform thickness and inter-lamella spacing. This arrangement lies at the origin of the blue-green iridescence of the organism's characteristic stripes, which is caused by multilayer interference. The multilayer is supported by a disordered array of spherical particles with an average diameter of 300nm, likely serving to enhance the contrast of the blue stripes. We present a full structural and optical characterization of this bio-mineralised marine photonic system, supported by optical FDTD modeling. [Preview Abstract] |
Monday, March 18, 2013 3:18PM - 3:30PM |
C45.00003: Time-resolved evolution of short- and long-range order during the transformation of amorphous calcium carbonate to calcite in the sea urchin embryo Chantel Tester, Ching-Hsuan Wu, Minna Krejci, Laura Mueller, Alex Park, Barry Lai, Si Chen, Chengjun Sun, Mahaling Balasubramanian, Derk Joester The biological use of amorphous mineral precursors is thought to be directly related to the ability to create single crystalline, yet composite materials with complex shapes that are beyond our synthetic capabilities. Despite considerable effort in recent years, it has not been possible to capture the mechanistic detail of the disorder-to-order transformation that is a key element of this process. This is largely due to lack of sensitivity, lack of temporal and spatial resolution, and artifacts of sample preparation. To overcome these challenges we use strontium as a probe for X-ray absorption spectroscopy (XAS). In pulse-chase experiments, sea urchin embryos incorporate Sr2$+$ from Sr-enriched seawater into small volumes of the developing endoskeleton. During the chase, the transformation of the newly deposited amorphous mineral is characterized by Sr-K$\alpha $ XAS of cryo-frozen whole embryos. We find that the initial mineral has short-range order resembling hydrated amorphous calcium carbonate. Within 3h, the short-range order of calcite is adopted, with long-range order developing over the next 20h. Pulse-chase experiments combined with heavy element labeling can be used in numerous mineralizing systems to study phase transformations during biological crystal growth. [Preview Abstract] |
Monday, March 18, 2013 3:30PM - 3:42PM |
C45.00004: Reaction-diffusion controlled growth of complex structures Willem Noorduin, L. Mahadevan, Joanna Aizenberg Understanding how the emergence of complex forms and shapes in biominerals came about is both of fundamental and practical interest. Although biomineralization processes and organization strategies to give higher order architectures have been studied extensively, synthetic approaches to mimic these self-assembled structures are highly complex and have been difficult to emulate, let alone replicate. The emergence of solution patterns has been found in reaction-diffusion systems such as Turing patterns and the BZ reaction. Intrigued by this spontaneous formation of complexity we explored if similar processes can lead to patterns in the solid state. We here identify a reaction-diffusion system in which the shape of the solidified products is a direct readout of the environmental conditions. Based on insights in the underlying mechanism, we developed a toolbox of engineering strategies to deterministically sculpt patterns and shapes, and combine different morphologies to create a landscape of hierarchical multi scale-complex tectonic architectures with unprecedented levels of complexity. These findings may hold profound implications for understanding, mimicking and ultimately expanding upon nature's morphogenesis strategies, allowing the synthesis of advanced highly complex microscale materials and devices. [Preview Abstract] |
Monday, March 18, 2013 3:42PM - 4:18PM |
C45.00005: Biomimetic control over size, shape and aggregation in magnetic nanoparticles Invited Speaker: Nico Sommerdijk Magnetite (Fe$_{3}$O$_{4})$ is a widespread magnetic iron oxide encountered in both geological and biomineralizing systems, which also has many technological applications, e.g. in ferrofluids, inks, magnetic data storage materials and as contrast agents in magnetic resonance imaging. As its magnetic properties depend largely on the size and shape of the crystals, control over crystal morphology is an important aspect in the application of magnetite nanoparticles, both in biology and synthetic systems. Indeed, in nature organisms such as magnetotactic bacteria demonstrate a precise control over the magnetite crystal morphology, resulting in uniform and monodisperse nanoparticles. The magnetite formation in these bacteria is believed to occur through the co-precipitation of Fe(II) and Fe(III) ions, which is also the most widely applied synthetic route in industry. Synthetic strategies to magnetite with controlled size and shape exist, but involve high temperatures and rather harsh chemical conditions. However, synthesis via co-precipitation generally yields poor control over the morphology and therefore over the magnetic properties of the obtained crystals. Here we demonstrate that by tuning the reaction kinetics we can achieve biomimetic control over the size and shape of magnetite crystals but also over their organization in solution as well as their magnetic properties. We employ amino acids-based polymers to direct the formation of magnetite in aqueous media at room temperature via both the co-precipitation and the partial oxidation method. By using 2D and 3D (cryo)TEM it is shown that acidic amino acid monomers are most effective in affecting the magnetite particle morphology. By changing the composition of the polymers we can tune the morphology, the dispersibility as well as the magnetic properties of these nanoparticles. [Preview Abstract] |
Monday, March 18, 2013 4:18PM - 4:30PM |
C45.00006: Understanding the biological stabilization of ferrihydrite and its transformation to magnetite Lyle Gordon, Derk Joester The biosynthesis of magnetite in the chiton tooth begins with the formation of ferrihydrite, which is transformed into magnetite. This strategy, which employs crystallization of a precursor into the desired polymorph, is generalized across a range of organisms. However, the specific biological factors that control the transformation are not known. Our results employing atom probe tomography of chiton tooth magnetite revealed the presence of acidic proteins binding sodium and magnesium ions associated with chitin nanofibers. Using a model system we are investigating the influence of organic and inorganic additives on the stabilization of ferrihydrite and the transformation to magnetite. I will discuss the influence of a range of organic and inorganic additives on the formation and transformation of ferrihydrite within the gel. We have found that acidic polymers stabilize ferrihydrite and prevent the formation of the crystalline polymorphs. Transformation of the ferrihydrite to magnetite upon addition of ferrous iron is observed as early as 30 minutes. Taken together, the contribution of these factors to magnetite biomineralization in the presence of an organic matrix will help to elucidate biological mechanisms for nucleation, stabilization, and transformation of iron oxides. [Preview Abstract] |
Monday, March 18, 2013 4:30PM - 4:42PM |
C45.00007: Probing physical and chemical changes in cortical bone due to osteoporosis and type 2 diabetes by solid-state NMR Donghua Zhou, Amanda Taylor, Beth Rendina, Brenda Smith Approximately 1.5 million fractures occur each year in the U.S. due to osteoporosis, which is characterized by decreased bone mineral density and deterioration of bone micro-architecture. On the other hand, type 2 diabetes also significantly increases fracture risks, despite having a normal or even higher bone mineral density. Solid-state NMR has been applied to bone tissues from normal and disease-inflicted mouse models to study structural and chemical dynamics as the disease progresses. Proton relaxation experiments were performed to measure water populations in the bone matrix and pores. Collagen-bound water has strong influence on bone resilience, while water content in the pores reveals amount and size of pores from micro- to millimeter range. Other biochemical and atomic-scale structural alterations in the mineral and organic phases and their interface were investigated by proton, phosphorus, and carbon NMR spectroscopy. Experiments were designed to individually detect different types of phosphorus environments: near the mineral surface, similar to hydroxyapatite, and deficient of hydrogens due to substitution of the hydroxyl group by other ions. A new method was also developed for accurate quantification of each phosphorus species. [Preview Abstract] |
Monday, March 18, 2013 4:42PM - 5:18PM |
C45.00008: Biomineralization and Biomimetics Invited Speaker: Joanna Aizenberg |
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