In Vitro Repair of a Biomineral with a Mesocrystal Structure

Thermally induced fragmentation of nanoscale calcite

Calcite nanorods ∼50 nm wide are thermally separated into nanoblocks.

Oriented Attachment of Calcite Nanocrystals: Formation of Single-Crystalline Configurations as 3D Bundles via Lateral Stacking of 1D Chains

The formation of single-crystalline configurations by the oriented attachment of calcite was experimentally demonstrated as 3D bundles in a nonaqueous system. In the initial stage, 1D short chains elongated in the c direction were formed through the primary oriented attachment of calcite nanoblocks ∼30 nm in diameter. The 3D bundles were then produced through subsequent side-by-side oriented attachment of the 1D chains in the progressive stage. Finally, micrometer-sized single-crystalline architectures were constructed via large-scale oriented attachment of the nanoscale building blocks with a decrease in repulsion force due to the surface charge.

1D oriented attachment of calcite nanocrystals: formation of single-crystalline rods through collision

Single-crystalline calcite nanorods elongated in the c direction formed through 1D oriented attachment of nanoblocks.

An NMR Study of Biomimetic Fluorapatite - Gelatine Mesocrystals

The mesocrystal system fluoroapatite—gelatine grown by double-diffusion is characterized by hierarchical composite structure on a mesoscale. In the present work we apply solid state NMR to characterize its structure on the molecular level and provide a link between the structural organisation on the mesoscale and atomistic computer simulations. Thus, we find that the individual nanocrystals are composed of crystalline fluorapatite domains covered by a thin boundary apatite-like layer. The latter is in contact with an amorphous layer, which fills the interparticle space. The amorphous layer is comprised of the organic matrix impregnated by isolated phosphate groups, Ca₃F motifs and water molecules. Our NMR data provide clear evidence for the existence of precursor complexes in the gelatine phase, which were not involved in the formation of apatite crystals, proving hence theoretical predictions on the structural pre-treatment of gelatine by ion impregnation. The interfacial interactions, which may be described as the glue holding the composite materials together, comprise hydrogen bond interactions with the apatite PO₄³⁻ groups. The reported results are in a good agreement with molecular dynamics simulations, which address the mechanisms of a growth control by collagen fibers, and with experimental observations of an amorphous cover layer in biominerals.

Incorporation of organic crystals into the interspace of oriented nanocrystals: morphologies and properties

Oriented nanocrystals, as seen in biominerals, have both the macroscopic hierarchical morphologies and the nanoscale interspace among the unit crystals. Here we studied the incorporation effects of the specific interspace in the oriented nanocrystals on the morphologies, properties, and applications of organic crystals. Organic crystals, such as 9-vinylcarbazole (VCz), azobenzene (AB), and pyrene (PY), were introduced into the specific interspace of oriented nanocrystals from the melts. The morphologies and properties of the incorporated organic crystals were systematically studied in these model cases. The incorporation of the organic crystals provided the composites with the original oriented nanocrystals. The incorporated organic crystals formed the single-crystalline structures even in the nanoscale interspace. The melts of the organic compounds were crystallized and grown in the interspace of the original materials. The incorporated organic crystals showed the specific phase transition behavior. The freezing points of the organic crystals were raised by the incorporation into the nanospace while the melting points were not changed. The hierarchical morphologies of the organic crystals were obtained after the dissolution of the original materials. The hierarchical morphologies of the original materials were replicated to the organic crystals. The incorporated organic crystal was polymerized without deformation of the hierarchical morphologies. The hierarchical polymer can be applied to the donor material for the generation of a larger amount of the charge-transfer complex with the acceptor molecule than the commercial polymer microparticles. The present work shows the potential use of the nanoscale interspace generated in the oriented nanocrystals.

Synthesis and optical properties of mesoporous β-Co(OH)(2) /brilliant blue G (G250) hybrid hierarchical structures

New mesoporous β-Co(OH)(2) /brilliant blue G (G250) hybrid hierarchical structures constructed by thin mesocrystal nanosheets can be synthesized by a one-step refluxing process under the synergistic effect of CTAB and G250. This approach opens up an avenue to access new novel inorganic/dye hybrid materials with hierarchical structures for pigment and electrocatalytic application.

Mesocrystals - Properties and Applications

Mesocrystals are a new class of nanostructured solid materials, which are most often made of crystallographically oriented nanoparticles. Structural features, properties, and possible applications of mesocrystals are summarized in this paper. Due to their unique structural features and the resulting physical and physicochemical properties, mesocrystals are expected to play a significant role in improving the performance of materials in many applications. These are as diverse as heterogeneous photocatalysts, electrodes, optoelectronics, biomedical materials, hard templates, and lightweight structural materials.