Growth plate cartilage (GP) serves as a dynamic site of active mineralization and offers a unique opportunity to investigate the cell-regulated matrix mineralization process. Transmission electron microscopy (TEM) provides a means for the direct observation of these mechanisms, offering the necessary resolution and chemical analysis capabilities. However, as mineral crystallinity is prone to artifacts using aqueous fixation protocols, sample preparation techniques are critical to preserve the mineralized tissue in its native form.
View Article and Find Full Text PDFPhotocatalyst systems combining donor polymers with acceptor molecules have shown the highest evolution rates for sacrificial hydrogen production from water for organic systems to date. Here, new donor molecules have been designed and synthesised taking inspiration from the structure-performance relationships which have been established in the development of non-fullerene acceptors. While a conventional bulk heterojunction (BHJ) pairing consists of a donor polymer and acceptor small molecule, here we have successfully reversed this approach by using new p-type small molecules in combination with a n-type conjugated polymer to produce non-conventional BHJ (ncBHJ) nanoparticles.
View Article and Find Full Text PDFCoccolithophores are marine phytoplankton that produce calcite mineral scales called coccoliths. Many stages in the synthesis of these structures are still unresolved, making it difficult to accurately quantify the energetic costs involved in calcification, required to determine the response coccolith mineralization will have to rising ocean acidification and temperature created by an increase in global CO2 concentrations. To clarify this, an improved understanding of how coccolithophores control the fundamental processes of crystallization, including nucleation, growth, and morphology, is needed.
View Article and Find Full Text PDFCalcium phosphates are widely studied in orthopedics and dentistry, to obtain biomimetic and antibacterial implants. However, the multi-substituted composition of mineralized tissues is not fully reproducible from synthetic procedures. Here, for the first time, we investigate the possible use of a natural, fluorapatite-based material, , seashell, resembling the composition of bone and enamel, as a biomaterial source for orthopedics and dentistry.
View Article and Find Full Text PDFActa Crystallogr B Struct Sci Cryst Eng Mater
April 2022
The crystal structure of Blatter's radical (1,3-diphenyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl) has been investigated between ambient pressure and 6.07 GPa. The sample remains in a compressed form of the ambient-pressure phase up to 5.
View Article and Find Full Text PDFX-ray data reveal the role of prestress in hierarchical biocomposites at the nanoscale.
View Article and Find Full Text PDFIncorporating additives within host single crystals is an effective strategy for producing composite materials with tunable mechanical, magnetic and optical properties. The type of guest materials that can be occluded can be limited, however, as incorporation is a complex process depending on many factors including binding of the additive to the crystal surface, the rate of crystal growth and the stability of the additives in the crystallisation solution. In particular, the size of occluded guests has been restricted to a few angstroms - as for single molecules - to a few hundred nanometers - as for polymer vesicles and particles.
View Article and Find Full Text PDFTime-resolved carbamazepine crystallization from wet ethanol has been monitored using a combination of cryoTEM and 3D electron diffraction. Carbamazepine is shown to crystallize exclusively as a dihydrate after 180 s. When the timescale was reduced to 30 s, three further polymorphs could be identified.
View Article and Find Full Text PDFThe function-optimized properties of biominerals arise from the hierarchical organization of primary building blocks. Alteration of properties in response to environmental stresses generally involves time-intensive processes of resorption and reprecipitation of mineral in the underlying organic scaffold. Here, we report that the load-bearing shells of the brachiopod Discinisca tenuis are an exception to this process.
View Article and Find Full Text PDFBiomineralization is a fundamental process key to the development of the skeleton. The phosphatase orphan phosphatase 1 (PHOSPHO1), which likely functions within extracellular matrix vesicles, has emerged as a critical regulator of biomineralization. However, the biochemical pathways that generate intravesicular PHOSPHO1 substrates are currently unknown.
View Article and Find Full Text PDFObjectives: This study investigated the effects of a new strontium-doped bioactive glass and fluoride on hydroxyapatite crystallization.
Methods: We designed an in vitro experiment with calcium phosphate (CaCl·2HO + KHPO in buffer solution) with different concentrations of strontium-doped bioactive glass (1 mg/mL or 5 mg/mL), and different concentrations of fluoride (0 ppm, 1 ppm or 5 ppm). Tris-buffered saline served as negative control.
Collagen type I is one of the major structural proteins in mammals, providing tissues such as cornea, tendon, bone, skin, and dentin with mechanical stability, strength, and toughness. Collagen fibrils are composed of collagen molecules arranged in a quarter-stagger array that gives rise to a periodicity of 67 nm along the fibril axis, with a 30 nm overlap zone and a 37 nm gap zone. The formation of such highly organized fibrils is a self-assembly process where electrostatic and hydrophobic interactions play a critical role in determining the staggering of the molecules with 67 nm periodicity.
View Article and Find Full Text PDFA simple two-spindle based lathe system for the preparation of cylindrical samples intended for X-ray tomography is presented. The setup can operate at room temperature as well as under cryogenic conditions, allowing the preparation of samples down to 20 and 50 µm in diameter, respectively, within minutes. Case studies are presented involving the preparation of a brittle biomineral brachiopod shell and cryogenically fixed soft brain tissue, and their examination by means of ptychographic X-ray computed tomography reveals the preparation method to be mainly free from causing artefacts.
View Article and Find Full Text PDFAlthough CuO is a commonly used narrow band gap semiconductor to fabricate visible response photocatalysts, up to date there are only a few reports on Ag co-catalysed TiO-CuO nanocomposites. Herein we report a facile wet chemical synthesis approach to prepare TiO-Ag-CuO ternary hybrid nanomaterials. Uniquely, both the effect of Ag content and the synthesis sequence of Ag deposition step was investigated on the visible decoloration rate.
View Article and Find Full Text PDF3D electron diffraction (3DED) has been used to follow polymorph evolution in the crystallization of glycine from aqueous solution. The three polymorphs of glycine which exist under ambient conditions follow the stability order β < α < γ. The least stable β polymorph forms within the first 3 min, but this begins to yield the α-form after only 1 min more.
View Article and Find Full Text PDFChitin is one of the most studied biopolymers but the understanding of how it assembles from molecules to microfibers is still limited. Organisms are able to assemble chitin with precise control over polymorphism, texture, and final morphology. The produced hierarchical structure leads to materials with outstanding mechanical properties.
View Article and Find Full Text PDFThe bone and dentin mainly consist of type-I collagen fibrils mineralized by hydroxyapatite (HAP) nanocrystals. In vitro biomimetic models based on self-assembled collagen fibrils have been widely used in studying the mineralization mechanism of type-I collagen. In this chapter, the protocol we used to build a biomimetic model for the mechanistic study of type-I collagen mineralization is described.
View Article and Find Full Text PDFA rapid and efficient method for the detection of hydroxyapatite (HAP) has been developed which shows superiority to existing well-established methods. This fluorescein-bisphosphonate probe is highly selective for HAP over other calcium minerals and is capable of detecting lower levels of calcification in cellular models than either hydrochloric acid-based calcium leaching assays or the Alizarin S stain. The probe has been shown to be effective in both in vitro vascular calcification models and in vitro bone calcification models.
View Article and Find Full Text PDFSteric bulk prevents the formation of strong bonds between Lewis acids and bases in frustrated Lewis pairs (FLPs), where latent reactivity makes these reagents transformative in small molecule activations and metal-free catalysis. However, their use as a platform for developing materials chemistry is unexplored. Here we report a fully macromolecular FLP, built from linear copolymers that containing either a sterically encumbered Lewis base or Lewis acid as a pendant functional group.
View Article and Find Full Text PDFUnderstanding and controlling nucleation is important for many crystallization applications. Calcium carbonate (CaCO) is often used as a model system to investigate nucleation mechanisms. Despite its great importance in geology, biology, and many industrial applications, CaCO nucleation is still a topic of intense discussion, with new pathways for its growth from ions in solution proposed in recent years.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2017
Early-stage reaction mechanisms for aragonite-promoting systems are relatively unknown compared to the more thermodynamically stable calcium carbonate polymorph, calcite. Using cryoTEM and SEM, the early reaction stages taking place during aragonite formation were identified in a highly supersaturated solution using an alcohol-water solvent, and an overall particle attachment growth mechanism was described for the system. In vitro evidence is provided for the solid-state transformation of amorphous calcium carbonate to aragonite, demonstrating the co-existence of both amorphous and crystalline material within the same aragonite needle.
View Article and Find Full Text PDFSemin Cell Dev Biol
October 2015
The wide diversity of biogenic minerals that is found in nature, each with its own morphology, mechanical properties and composition, is remarkable. In order to produce minerals that are optimally adapted for their function, biomineralisation usually occurs under strict cellular control. This control is exerted by specialised proteins and polysaccharides that assemble into a 3-dimensional organic matrix framework, forming a microenvironment where mineral deposition takes place.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
February 2015
Complex polymeric nanospheres were formed in water from comb-like amphiphilic block copolymers. Their internal morphology was determined by three-dimensional cryo-electron tomographic analysis. Varying the polymer molecular weight (MW) and the hydrophilic block weight content allowed for fine control over the internal structure.
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