Direct fabrication of large micropatterned single crystals

Bioinspired Synthesis of CaCO3 Superstructures through a Novel Hydrogel Composite Membranes Mineralization Platform: A Comprehensive View

Hydrogel composite membranes (HCMs) are used as novel mineralization platforms for the bioinspired synthesis of CaCO3 superstructures. A comprehensive statistical analysis of the experimental results reveals quantitative relationships between crystallization conditions and crystal texture and a strong selectivity toward complex morphologies when monomers bearing carboxyl and hydroxyl groups are used together in the hydrogel layer synthesis in HCMs.

Room temperature synthesis of flower-like CaCO3 architectures

A proposed hierarchical self-assembly mechanism of the formation of flower-like vaterite superstructures.

The Crystal Hotel: A Microfluidic Approach to Biomimetic Crystallization

A "crystal hotel" microfluidic device that allows crystal growth in confined volumes to be studied in situ is used to produce large calcite single crystals with predefined crystallographic orientation, microstructure, and shape by control of the detailed physical environment, flow, and surface chemistry. This general approach can be extended to form technologically important, nanopatterned single crystals.

Sponge-like nanoporous single crystals of gold

Single crystals in nature often demonstrate fascinating intricate porous morphologies rather than classical faceted surfaces. We attempt to grow such crystals, drawing inspiration from biogenic porous single crystals. Here we show that nanoporous single crystals of gold can be grown with no need for any elaborate fabrication steps. These crystals are found to grow following solidification of a eutectic composition melt that forms as a result of the dewetting of nanometric thin films. We also present a kinetic model that shows how this nano-porous single-crystalline structure can be obtained, and which allows the potential size of the porous single crystal to be predicted. Retaining their single-crystalline nature is due to the fact that the full crystallization process is faster than the average period between two subsequent nucleation events. Our findings clearly demonstrate that it is possible to form single-crystalline nano porous metal crystals in a controlled manner.

Naturally occurring single crystals can exhibit various intricate porous morphologies. Here, the authors are able to grow nanoporous single crystals of gold following solidification of a eutectic composition melt that forms as a result of the dewetting of nanometric thin films.

Formation of Helically Structured Chitin/CaCO3 Hybrids through an Approach Inspired by the Biomineralization Processes of Crustacean Cuticles

Chitin/CaCO3 hybrids with helical structures are formed through a biomineralization-inspired crystallization process under ambient conditions. Liquid-crystalline chitin whiskers are used as helically ordered templates. The liquid-crystalline structures are stabilized by acidic polymer networks which interact with the chitin templates. The crystallization of CaCO3 is conducted by soaking the templates in the colloidal suspension of amorphous CaCO3 (ACC) at room temperature. At the initial stage of crystallization, ACC particles are introduced inside the templates, and they crystallize to CaCO3 nanocrystals. The acidic polymer networks induce CaCO3 crystallization. The characterization of the resultant hybrids reveals that they possess helical order and homogeneous hybrid structures of chitin and CaCO3 , which resemble the structure and composition of the exoskeleton of crustaceans.

Fabricating Hexagonal Al-Doped LiCoO2 Nanomeshes Based on Crystal-Mismatch Strategy for Ultrafast Lithium Storage

In the designed synthesis, low crystal-mismatch strategy has been applied in the synthesis of ion-doped LiCoO2 materials, and a good success of single crystal property has been achieved between the precursor and the final sample for the first time. The hexagonal LiCo0.8Al0.26O2 (LCAO) nanomesh possesses several advantages in morphology and crystal structure, including mesoporous structure, single crystal, atomic even distribution, high exposing surface area as (100) or their equivalent planes, and shortened Li ions diffusion distance. All the merits are beneficial to the application in Li-ion batteries (LIBs) cathode, for example, accelerating Li ions diffusion rate, improving the Li ions shuttle between the LCAO nanomesh and electrolyte, and reducing the Li ions capacitive behavior during Li intercalation. Hence, our research adopts Al-contained precursor with morphology of hexagonal nanoplates to fabricate designed Al-doped LiCoO2 nanomeshes and greatly improves the cathode performance in LIBs.

Quick Fabrication of Large-area Organic Semiconductor Single Crystal Arrays with a Rapid Annealing Self-Solution-Shearing Method

In this paper, we developed a new method to produce large-area single crystal arrays by using the organic semiconductor 9, 10-bis (phenylethynyl) anthracene (BPEA). This method involves an easy operation, is efficient, meets the demands of being low-cost and is independent of the substrate for large-area arrays fabrication. Based on these single crystal arrays, the organic field effect transistors exhibit the superior performance with the average mobility extracting from the saturation region of 0.2 cm² V⁻¹s⁻¹ (the highest 0.47 cm² V⁻¹s⁻¹) and on/off ratio exceeding 10⁵. In addition, our single crystal arrays also show a very high photoswitch performance with an on/off current ratio up to 4.1 × 10⁵, which is one of the highest values reported for organic materials. It is believed that this method provides a new way to fabricate single crystal arrays and has the potential for application to large area organic electronics.

Dual Roles of the Lysine-Rich Matrix Protein (KRMP)-3 in Shell Formation of Pearl Oyster, Pinctada fucata

Matrix proteins play important roles in shell formation. Our group firstly isolated three cDNAs encoding lysine-rich matrix protein from Pinctada fucata in 2006. However, the functions of KRMPs are not fully understood. In addition, KRMPs contain two functional domains, the basic domain and the Gly/Tyr domain respectively. Based on the modular organization, the roles of their two domains were poorly characterized. Furthermore, KRMPs were then reported in other two species, P. maxima and P. margaritifera, which indicated that KRMPs might be very important for shell formation. In this study, the characterization and function of KRMP-3 and its two functional domains were studied in vitro through purification of recombinant glutathione S-transferase tagged KRMP-3 and two KRMP-3 deletion mutants. Western blot and immunofluorescence revealed that native KRMP-3 existed in the EDTA-insoluble matrix of the prismatic layer and was located in the organic sheet and the prismatic sheath. Recombinant KRMP-3 (rKRMP-3) bound tightly to chitin and this binding capacity was duo to the Gly/Tyr-rich region. rKRMP-3 inhibited the precipitation of CaCO₃, affected the crystal morphology of calcite and inhibited the growth of aragonite in vitro, which was almost entirely attributed to the lysine-rich region. The results present direct evidence of the roles of KRMP-3 in shell biomineralization. The functional rBR region was found to participate in the growth control of crystals and the rGYR region was responsible to bind to chitin.

Amorphous calcium carbonate controls avian eggshell mineralization: A new paradigm for understanding rapid eggshell calcification

Avian eggshell mineralization is the fastest biogenic calcification process known in nature. How this is achieved while producing a highly crystalline material composed of large calcite columnar single crystals remains largely unknown. Here we report that eggshell mineral originates from the accumulation of flat disk-shaped amorphous calcium carbonate (ACC) particles on specific organic sites on the eggshell membrane, which are rich in proteins and sulfated proteoglycans. These structures known as mammillary cores promote the nucleation and stabilization of a amorphous calcium carbonate with calcitic short range order which predetermine the calcite composition of the mature eggshell. The amorphous nature of the precursor phase was confirmed by the diffuse scattering of X-rays and electrons. The nascent calcitic short-range order of this transient mineral phase was revealed by infrared spectroscopy and HRTEM. The ACC mineral deposited around the mammillary core sites progressively transforms directly into calcite crystals without the occurrence of any intermediate phase. Ionic speciation data suggest that the uterine fluid is equilibrated with amorphous calcium carbonate, throughout the duration of eggshell mineralization process, supporting that this mineral phase is constantly forming at the shell mineralization front. On the other hand, the transient amorphous calcium carbonate mineral deposits, as well as the calcite crystals into which they are converted, form by the ordered aggregation of nanoparticles that support the rapid mineralization of the eggshell. The results of this study alter our current understanding of avian eggshell calcification and provide new insights into the genesis and formation of calcium carbonate biominerals in vertebrates.

Patterning two-dimensional chalcogenide crystals of Bi2Se3 and In2Se3 and efficient photodetectors

Patterning of high-quality two-dimensional chalcogenide crystals with unique planar structures and various fascinating electronic properties offers great potential for batch fabrication and integration of electronic and optoelectronic devices. However, it remains a challenge that requires accurate control of the crystallization, thickness, position, orientation and layout. Here we develop a method that combines microintaglio printing with van der Waals epitaxy to efficiently pattern various single-crystal two-dimensional chalcogenides onto transparent insulating mica substrates. Using this approach, we have patterned large-area arrays of two-dimensional single-crystal Bi₂Se₃ topological insulator with a record high Hall mobility of ∼1,750 cm² V⁻¹ s⁻¹ at room temperature. Furthermore, our patterned two-dimensional In₂Se₃ crystal arrays have been integrated and packaged to flexible photodetectors, yielding an ultrahigh external photoresponsivity of ∼1,650 A W⁻¹ at 633 nm. The facile patterning, integration and packaging of high-quality two-dimensional chalcogenide crystals hold promise for innovations of next-generation photodetector arrays, wearable electronics and integrated optoelectronic circuits.

Two-dimensional chalcogenides offer great potential in electronics, but accurate control of their growth is difficult. Here, the authors combine microintaglio printing and van der Waals epitaxy to pattern various large-area arrays of single-crystal chalcogenides with remarkable properties.

Dehydration and crystallization of amorphous calcium carbonate in solution and in air

The mechanisms by which amorphous intermediates transform into crystalline materials are poorly understood. Currently, attracting enormous interest is the crystallization of amorphous calcium carbonate, a key intermediary in synthetic, biological and environmental systems. Here we attempt to unify many contrasting and apparently contradictory studies by investigating this process in detail. We show that amorphous calcium carbonate can dehydrate before crystallizing, both in solution and in air, while thermal analyses and solid-state nuclear magnetic resonance measurements reveal that its water is present in distinct environments. Loss of the final water fraction--comprising less than 15% of the total--then triggers crystallization. The high activation energy of this step suggests that it occurs by partial dissolution/recrystallization, mediated by surface water, and the majority of the particle then crystallizes by a solid-state transformation. Such mechanisms are likely to be widespread in solid-state reactions and their characterization will facilitate greater control over these processes.

Brittlestar-inspired microlens arrays made of calcite single crystals

Unique concave microlens arrays (MLAs) made of calcite single crystals with tunable crystal orientations can be readily fabricated by template-assisted epitaxial growth in solution without additives under ambient conditions. While the non-birefringent calcite (001) MLA showed excellent imaging performance like brittlestar's microlens arrays, the birefringent calcite (104) MLA exhibited remarkable polarization-dependent optical properties.

A crucial process: organic matrix and magnesium ion control of amorphous calcium carbonate crystallization on β-chitin film

ACC transformation processes occurring on chitin film mediated by a water soluble matrix or magnesium ions in aqueous solution were investigated.

A perspective on underlying crystal growth mechanisms in biomineralization: solution mediated growth versus nanosphere particle accretion

A working hypothesis for the understanding of amorphous-to-crystalline transformations in biogenic skeletal materials formed through transient amorphous precursor phases.

Tuning of morphology and polymorphs of carbonate/polymer hybrids using photoreactive polymer templates

Crystallization of inorganic carbonates on photolithographic polymer matrices led to development of inorganic/organic hybrid materials with photo-controlled and self-organized structures.

Bioinspired structural materials

Natural structural materials are built at ambient temperature from a fairly limited selection of components. They usually comprise hard and soft phases arranged in complex hierarchical architectures, with characteristic dimensions spanning from the nanoscale to the macroscale. The resulting materials are lightweight and often display unique combinations of strength and toughness, but have proven difficult to mimic synthetically. Here, we review the common design motifs of a range of natural structural materials, and discuss the difficulties associated with the design and fabrication of synthetic structures that mimic the structural and mechanical characteristics of their natural counterparts.

Optical properties of self-organized gold nanorod-polymer hybrid films

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.

Nanocrystalline calcitic lens arrays fabricated by self-assembly followed by amorphous-to-crystalline phase transformation

Natural calcium carbonate-based nanocomposites often have superior physical properties and provide a comprehensive source for bioinspired synthetic materials. Here we present thermodynamically stable, transparent CaCO3 microlens arrays (MLA) produced by transforming an amorphous CaCO3 phase into nanocrystalline calcite. We analyze the structure and properties of crystallized MLA by X-ray scattering, transmitted and polarized light microscopy, and electron microscopy and find that MLA are crystallized in spherulite-like patterns without changing the shape of the microlens. The key finding is that nanocrystallinity of the calcite formed diminishes structural anisotropy on the wavelength scale and results in greatly reduced birefringent effects. The remnant preferred orientation of the optical axes of calcite crystals in the plane of the microlens arrays leads to some directionality of optical properties, which may be beneficial for technical applications.

In situ TEM imaging of CaCO₃ nucleation reveals coexistence of direct and indirect pathways

Mechanisms of nucleation from electrolyte solutions have been debated for more than a century. Recent discoveries of amorphous precursors and evidence for cluster aggregation and liquid-liquid separation contradict common assumptions of classical nucleation theory. Using in situ transmission electron microscopy (TEM) to explore calcium carbonate (CaCO3) nucleation in a cell that enables reagent mixing, we demonstrate that multiple nucleation pathways are simultaneously operative, including formation both directly from solution and indirectly through transformation of amorphous and crystalline precursors. However, an amorphous-to-calcite transformation is not observed. The behavior of amorphous calcium carbonate upon dissolution suggests that it encompasses a spectrum of structures, including liquids and solids. These observations of competing direct and indirect pathways are consistent with classical predictions, whereas the behavior of amorphous particles hints at an underlying commonality among recently proposed precursor-based mechanisms.

A Review of Product Design for Additive Manufacturing

Additive Manufacturing (AM) is the digital manufacturing technology by which products are fabricated directly from computer models by selectively curing, depositing or consolidating materials in successive layers. The technology has provided an opportunity to rethink the methods of product design to maximize the product performance through the synthesis of material compositions, structure, and sizes. This overview is created to relate the unique capabilities of AM technologies and discuss the methods of product design. Finally, the current problems and difficulties in this field are discussed in this paper, and this paper proposes the development direction of the product design for additive manufacturing in the future.

Crustacean-derived biomimetic components and nanostructured composites

Over millions of years, the crustacean exoskeleton has evolved into a rigid, tough, and complex cuticle that is used for structural support, mobility, protection of vital organs, and defense against predation. The crustacean cuticle is characterized by a hierarchically arranged chitin fiber scaffold, mineralized predominately by calcium carbonate and/or calcium phosphate. The structural organization of the mineral and organic within the cuticle occurs over multiple length scales, resulting in a strong and tough biological composite. Here, the ultrastructural details observed in three species of crustacean are reviewed: the American lobster (Homarus americanus), the edible crab (Cancer pagurus), and the peacock mantis shrimp (Odontodactylus scyllarus). The Review concludes with a discussion of recent advances in the development of biomimetics with controlled organic scaffolding, mineralization, and the construction of nanoscale composites, inspired by the organization and formation of the crustacean cuticle.

Formation of curved micrometer-sized single crystals

Crystals in nature often demonstrate curved morphologies rather than classical faceted surfaces. Inspired by biogenic curved single crystals, we demonstrate that gold single crystals exhibiting curved surfaces can be grown with no need of any fabrication steps. These single crystals grow from the confined volume of a droplet of a eutectic composition melt that forms via the dewetting of nanometric thin films. We can control their curvature by controlling the environment in which the process is carried out, including several parameters, such as the contact angle and the curvature of the drops, by changing the surface tension of the liquid drop during crystal growth. Here we present an energetic model that explains this phenomenon and predicts why and under what conditions crystals will be forced to grow with the curvature of the microdroplet even though the energetic state of a curved single crystal is very high.

Rational strategy for shaped nanomaterial synthesis in reverse micelle reactors

The shape-controlled synthesis of nanoparticles was established in single-phase solutions by controlling growth directions of crystalline facets on seed nanocrystals kinetically; however, it was difficult to rationally predict and design nanoparticle shapes. Here we introduce a methodology to fabricate nanoparticles in smaller sizes by evolving shapes thermodynamically. This strategy enables a more rational approach to fabricate shaped nanoparticles by etching specific positions of atoms on facets of seed nanocrystals in reverse micelle reactors where the surface energy gradient induces desorption of atoms on specific locations on the seed surfaces. From seeds of 12 nm palladium nanocubes, the shape is evolved to concave nanocubes and finally hollow nanocages in the size ~10 nm by etching the center of {200} facets. The high surface area-to-volume ratio and the exposure of a large number of palladium atoms on ledge and kink sites of hollow nanocages are advantageous to enhance catalytic activity and recyclability.

Aragonite nanorods in calcium carbonate/polymer hybrids formed through self-organization processes from amorphous calcium carbonate solution

Nanostructured inorganic/polymer hybrid thin films comprising aragonite nanorods derived from aqueous suspensions of amorphous calcium carbonate (ACC) are prepared. For the formation of calcium carbonate (CaCO₃)/polymer hybrids, spincoated and annealed films of poly(vinyl alcohol) (PVA) that function as polymer matrices are soaked in aqueous colloidal solutions dispersing ACC stabilized by poly(acrylic acid) (PAA). In the initial stage, calcite thin films form on the surface. Subsequently, aragonite crystals start to form inside the PVA matrix that contains PVA crystallites which induce aragonite nucleation. Nanostructured hybrids composed of calcite thin films consisting of nanoparticles and assembled aragonite nanorods are formed in the matrices of PVA.

25th anniversary article: Artificial carbonate nanocrystals and layered structural nanocomposites inspired by nacre: synthesis, fabrication and applications

Rigid biological systems are increasingly becoming a source of inspiration for the fabrication of next generation advanced functional materials due to their diverse hierarchical structures and remarkable engineering properties. Among these rigid biomaterials, nacre, as the main constituent of the armor system of seashells, exhibiting a well-defined 'brick-and-mortar' architecture, excellent mechanical properties, and interesting iridescence, has become one of the most attractive models for novel artificial materials design. In this review, recent advances in nacre-inspired artificial carbonate nanocrystals and layered structural nanocomposites are presented. To clearly illustrate the inspiration of nacre, the basic principles relating to plate-like aragonite single-crystal growth and the contribution of hierarchical structure to outstanding properties in nacre are discussed. The inspiration of nacre for the synthesis of carbonate nanocrystals and the fabrication of layered structural nanocomposites is also discussed. Furthermore, the broad applications of these nacre inspired materials are emphasized. Finally, a brief summary of present nacre-inspired materials and challenges for the next generation of nacre-inspired materials is given.

Calcium oxalate crystallization in the presence of amphiphilic phosphoproteins

To gain more insight into protein structure–function relationships that govern biomineralization is an exciting and challenging task.