Journal Article Crystallization by Amorphous Particle Attachment and the Evolution of Texture in Biogenic Calcium Carbonate Get access Vanessa Schoeppler, Vanessa Schoeppler Department of Physics, University of California, Berkeley, USA Corresponding author: vschoeppler@lbl.gov Search for other works by this author on: Oxford Academic Google Scholar Deborah Stier, Deborah Stier B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany Search for other works by this author on: Oxford Academic Google Scholar Benjamin H Savitzky, Benjamin H Savitzky National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar Colin Ophus, Colin Ophus National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar Matthew A Marcus, Matthew A Marcus Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, USA Search for other works by this author on: Oxford Academic Google Scholar Karen C Bustillo, Karen C Bustillo National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar Igor Zlotnikov Igor Zlotnikov B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Pages 398–399, https://doi.org/10.1017/S1431927622002318 Published: 01 August 2022
The MHz-range ultrasonic pulse-echo technique was used to measure the longitudinal and shear sound velocities for different cuts of natural mineral Aragonite and of the nacre of Nautilus pompilius shell followed by the extraction of the elastic constants for both materials. On average, elastic stiffnesses of the biogenic shell aragonite were about 30% lower compared to the mineral. For constants related to BAW polarization along Z-direction, the difference was even larger than 50%, going along with strong acoustic attenuation. Laser Doppler vibrometer (LDV) measurements on both types of samples revealed a strongly different vibration behavior depending on the microstructure of the mineral and the shell samples.Additionally, two-dimensional bulk acoustic wave (BAW) field distributions were measured on both types of samples by means of Laser Doppler vibrometry (LDV)
We introduce the effective mass of the nanoindenter tip/sample assembly into the nanoscale dynamic modulus mapping technique that allows us to extract the correct storage modulus from the measured contact stiffness. We show that the developed approach successfully works for both stiff ceramics, such as fused quartz, and much compliant polymer materials, such as polycarbonate (PC) and poly(methyl methacrylate) (PMMA).
Biomimetic composite materials consisting of vanadium pentoxide (V2O5) and a liquid crystal (LC) “gluing” polymer were manufactured exhibiting six structural levels of hierarchy, formed through LC phases. The organic matrix was a polyoxazoline with pendant cholesteryl and carboxyl units, forming a lyotropic phase with the same structural orientation extending up to hundreds of micrometers upon shearing, and binding to V2O5 via hydrogen bridges. Composites consisting of V2O5–LC polymer hybrid fibers with a pronounced layered structuring were obtained. The V2O5–LC polymer hybrid fibers consist of aligned V2O5 ribbons, composed of self-assembled V2O5 sheets, encasing a chiral nematic polymer matrix. The structures of the V2O5–LC polymer composites strongly depend on the preparation method, i.e., the phase-transfer method from aqueous to organic medium, in which the polymer forms LC phases. Notably, highly defined micro- and nanostructures were obtained when initiating the synthesis using V2O5 tactoids with preoriented nanoparticle building units, even when using isotropic V2O5 dispersions. Shear-induced hierarchical structuring of the composites was observed, as characterized from the millimeter and micrometer down to the nanometer length scales using complementary optical and electron microscopy, SAXS, μCT, and mechanical nanoindentation.
Crystallization by particle attachment (CPA) is a gradual process where each step has its own thermodynamic and kinetic constrains defining a unique pathway of crystal growth. An important example is biomineralization of calcium carbonate through amorphous precursors that are morphed into shapes and textural patterns that cannot be envisioned by the classical monomer-by-monomer approach. Here, a mechanistic link between the collective kinetics of mineral deposition and the emergence of crystallographic texture is established. Using the prismatic ultrastructure in bivalve shells as a model, a fundamental leap is made in the ability to analytically describe the evolution of form and texture of biological mineralized tissues and to design the structure and crystallographic properties of synthetic materials formed by CPA.
Fractal-like, intricate morphologies are known to exhibit beneficial mechanical behavior in various engineering and technological domains. The evolution of fractal-like, internal walls of ammonoid cephalopod shells represent one of the most clear evolutionary trends toward complexity in biology, but the driver behind their iterative evolution has remained unanswered since the first hypotheses introduced in the early 1800s. We show a clear correlation between the fractal-like morphology and structural stability. Using linear and nonlinear computational mechanical simulations, we demonstrate that the increase in the complexity of septal geometry leads to a substantial increase in the mechanical stability of the entire shell. We hypothesize that the observed tendency is a driving force toward the evolution of the higher complexity of ammonoid septa, providing the animals with superior structural support and protection against predation. Resolving the adaptational value of this unique trait is vital to fully comprehend the intricate evolutionary trends between morphology, ecological shifts, and mass extinctions through Earth's history.
The metatarsal lyriform organ of the Central American wandering spider Cupiennius salei is its most sensitive vibration detector. It is able to sense a wide range of vibration stimuli over four orders of magnitude in frequency between at least as low as 0.1 Hz and several kilohertz. Transmission of the vibrations to the slit organ is controlled by a cuticular pad in front of it. While the mechanism of high-frequency stimulus transfer (above ca 40 Hz) is well understood and related to the viscoelastic properties of the pad's epicuticle, it is not yet clear how low-frequency stimuli (less than 40 Hz) are transmitted. Here, we study how the pad material affects the pad's mechanical properties and thus its role in the transfer of the stimulus, using a variety of experimental techniques, such as X-ray micro-computed tomography for three-dimensional imaging, X-ray scattering for structural analysis, and atomic force microscopy and scanning electron microscopy for surface imaging. The mechanical properties were investigated using scanning acoustic microscopy and nanoindentation. We show that large tarsal deflections cause large deformation in the distal highly hydrated part of the pad. Beyond this region, a sclerotized region serves as a supporting frame which resists the deformation and is displaced to push against the slits, with displacement values considerably scaled down to only a few micrometres. Unravelling the structural arrangement in such specialized structures may provide conceptual ideas for the design of new materials capable of controlling a technical sensor's specificity and selectivity, which is so typical of biological sensors.
Abstract Biominerals are complex inorganic‐organic structures that often show excellent mechanical properties. Here a bio‐inspired study of a remarkably simple synthetic system is presented in which only one charged polymer additive (poly(sodium 4‐styrenesulfonate)) is able to induce hierarchical structuring of calcite similar to biominerals. The interaction of the negatively charged polymer with the nucleation and growth of the mineral, in particular via selective adsorption to internal and external (001) facets of the calcite lattice, implies structural features from the micrometer down to the nanometer level. The crystals exhibit a distinct rounded morphology and a controlled orientation. Moreover, the polymer molecules are occluded within the crystals with different concentrations in well‐defined regions. This leads to the induction of a mesoscale structure based on 100 nm sized mineral building blocks with granular substructure and rough surface, as well as small modifications of the crystallographic structure. Such a combination of hierarchically organized structural features has previously only been reported for biogenic calcite, which is typically grown in a complex process involving multiple organic additives. It is also shown that the organic occlusions in the calcite‐PSS hybrid crystals strongly affect the mechanical performance, as known for some biominerals.
High fractions of gold nanorods were locally aligned by means of a polymeric liquid crystalline phase. The gold nanorods constituting >80 wt % of the thin organic–inorganic composite films form a network with side-by-side and end-to-end combinations. Organization into these network structures was induced by shearing gold nanorod–LC polymer dispersions via spin-coating. The LC polymer is a polyoxazoline functionalized with pendent cholesteryl and carboxyl side groups enabling the polymer to bind to the CTAB stabilizer layer of the gold nanorods via electrostatic interactions, thus forming the glue between organic and inorganic components, and to form a chiral nematic lyotropic phase. The self-assembled locally oriented gold nanorod structuring enables control over collective optical properties due to plasmon resonance coupling, reminiscent of enhanced optical properties of natural biomaterials.
