Influence of Polyphosphate on the Mineralization Balance of Tooth Enamel.

Dental minerals are in an equilibrium state of demineralization and remineralization, which can be disrupted by pathogenic bacteria to cause dental caries. While the inorganic polymer polyphosphate (polyP) is ubiquitous in living organisms and is also widely involved in mineralization regulations, its specific influence on the mineralization balance of teeth remains unclear. As a concept-and-proof study, the effects of polyP on the demineralization and remineralization of teeth are investigated on dental enamel (the highly mineralized outer covering tissue of teeth) from the perspective of mineralization balance.

Metastable Calcium Phosphate Cluster-Involved Mineralization Process Regulated by a Dual Biomolecule System Toward the Application in Dentinal Tubules Occlusion.

Dentin hypersensitivity caused by the exposure of dentinal tubules is affecting a significant portion of the population. With promising prospects, the biomimetic mineralization materials used in treating dentin hypersensitivity are expected to possess a metastable characteristic, for which they can easily penetrate the tubules and the surrounding tissues, but then occlude them via a transformation of size and phase immediately. Herein, this study develops a metastable calcium phosphate cluster (MCPC)-involved mineralization process, which is regulated by dual biological macromolecules: bovine serum albumin (BSA) and poly-L-lysine (PLL).

The glycerol stabilized calcium phosphate cluster for rapid remineralization of tooth enamel by a water-triggered transformation.

Remineralization is a common strategy for the repair of early demineralized tooth enamels, but the harsh dynamic oral environment often hampers its efficacy. Rapid remineralization is expected to address this challenge, however, the stabilizers of remineralization materials often resist their transformation required for repair. Here, by dissolving the ions of calcium and phosphate in glycerol-dominant solvents, we obtain the calcium phosphate clusters (1-2 nm), which are stabilized by glycerol (with high viscosity and affinity to clusters), but can perform a fast enamel repair via the water-triggered transformation in both static and dynamic environments.

Inorganic Pyrophosphate at Serum Concentration May Not Be Able to Inhibit Mineralization: A Study in Aqueous Solutions and Serum.

The constituent ions of calcium phosphate in body fluids are in the supersaturated state and tend to form minerals physiologically or pathologically. Inorganic pyrophosphate (PPi) has been considered as one of the most important inhibitors against the formation of calcium phosphate minerals. However, serum PPi concentrations in humans are maintained at a level of several μmol/L, and its effectiveness and mechanism for mineralization inhibition remain ambiguous.

Amorphous 1-D nanowires of calcium phosphate/pyrophosphate: A demonstration of oriented self-growth of amorphous minerals.

Amorphous inorganic solids are traditionally isotropic, thus, it is believed that they only grow in a non-preferential way without the assistance of regulators, leading to the morphologies of nanospheres or irregular aggregates of nanoparticles. However, in the presence of (ortho)phosphate (Pi) and pyrophosphate ions (PPi) which have synergistic roles in biomineralization, the highly elongated amorphous nanowires (denoted ACPPNs) form in a regulator-free aqueous solution (without templates, additives, organics, etc). Based on thorough characterization and tracking of the formation process (e.

Wnt3a-Loaded Hydroxyapatite Nanowire@Mesoporous Silica Core-Shell Nanocomposite Promotes the Regeneration of Dentin-Pulp Complex via Angiogenesis, Oxidative Stress Resistance, and Odontogenic Induction of Stem Cells.

Pulp exposure often leads to pulp necrosis, root fractures, and ultimate tooth loss. The repair of the exposure site with pulp capping treatment is of great significance to preserving pulp vitality, but its efficacy is impaired by the low bioactivity of capping materials and cell injuries from the local accumulation of oxidative stress. This study develops a Wnt3a-loaded hydroxyapatite nanowire@mesoporous silica (Wnt3a-HANW@MpSi) core-shell nanocomposite for pulp capping treatments.

Introducing the crystalline phase of dicalcium phosphate monohydrate.

Calcium orthophosphates (CaPs) are important in geology, biomineralization, animal metabolism and biomedicine, and constitute a structurally and chemically diverse class of minerals. In the case of dicalcium phosphates, ever since brushite (CaHPO·2HO, dicalcium phosphate dihydrate, DCPD) and monetite (CaHPO, dicalcium phosphate, DCP) were first described in 19 century, the form with intermediary chemical formula CaHPO·HO (dicalcium phosphate monohydrate, DCPM) has remained elusive. Here, we report the synthesis and crystal structure determination of DCPM.

Deformable Biomaterials Based on Ultralong Hydroxyapatite Nanowires.

Hydroxyapatite (HAP) biomaterials with high biocompatibility, bioactivity, and osteoconductivity/osteoinductivity have many applications in the biomedical fields. The traditional HAP materials usually feature high brittleness. Although hybridizing HAP with polymers can obtain deformable materials, their deformability is mainly contributed by polymers.

Enzymatic Reaction Generates Biomimic Nanominerals with Superior Bioactivity.

In vivo mineralization is a multistep process involving mineral-protein complexes and various metastable compounds in vertebrates. In this complex process, the minerals produced in the mitochondrial matrix play a critical role in initiating extracellular mineralization. However, the functional mechanisms of the mitochondrial minerals are still a mystery.

Biodegradable nanocomposite of glycerol citrate polyester and ultralong hydroxyapatite nanowires with improved mechanical properties and low acidity.

Glycerol citrate polyester based on the condensation of glycerol and citric acid has a great potential in biomedical applications owing to biocompatible monomers and biodegradation properties. However, the applications of glycerol citrate polyester are impaired by its poor mechanical properties and high acidity caused by citric acid produced in the degradation process. In this work, a new kind of nanocomposite has been developed using ultralong hydroxyapatite (HAP) nanowires as the "skeleton", and strongly bound glycerol citrate polyester as the "muscle".

Hydroxyapatite Nanowire-Based All-Weather Flexible Electrically Conductive Paper with Superhydrophobic and Flame-Retardant Properties.

How to survive under various harsh working conditions is a key challenge for flexible electronic devices because their performances are always susceptible to environments. Herein, we demonstrate the novel design and fabrication of a new kind of the all-weather flexible electrically conductive paper based on ultralong hydroxyapatite nanowires (HNs) with unique combination of the superhydrophobic surface, electrothermal effect, and flame retardancy. The superhydrophobic surface with water repellency stabilizes the electrically conductive performance of the paper in water.

Low-Cost and Scaled-Up Production of Fluorine-Free, Substrate-Independent, Large-Area Superhydrophobic Coatings Based on Hydroxyapatite Nanowire Bundles.

To date, the scaled-up production and large-area applications of superhydrophobic coatings are limited because of complicated procedures, environmentally harmful fluorinated compounds, restrictive substrates, expensive equipment, and raw materials usually involved in the fabrication process. Herein, the facile, low-cost, and green production of superhydrophobic coatings based on hydroxyapatite nanowire bundles (HNBs) is reported. Hydrophobic HNBs are synthesised by using a one-step solvothermal method with oleic acid as the structure-directing and hydrophobic agent.

Dopamine-modified highly porous hydroxyapatite microtube networks with efficient near-infrared photothermal effect, enhanced protein adsorption and mineralization performance.

In the last decade, the porous hydroxyapatite (HAP) scaffold has been investigated for the application in tissue engineering owing to its good bioactivity and high biocompatibility. In this work, the dopamine-modified highly porous hydroxyapatite microtube three-dimensional (3-D) networks with efficient near-infrared photothermal effect, enhanced protein adsorption and mineralization performance have been prepared through a facile method. The dopamine-modified highly porous HAP networks exhibit ultrahigh porosity (90.

Porous hollow microspheres of amorphous calcium phosphate: soybean lecithin templated microwave-assisted hydrothermal synthesis and application in drug delivery.

Calcium phosphate biomaterials are very promising for various biomedical applications owing to their excellent biocompatibility and biodegradability. Calcium phosphate nanostructured materials with a porous and hollow structure are excellent drug carriers due to their advantages such as high biocompatibility, large specific surface area, nanosized channels for drug loading and release, high drug loading capacity and pH-responsive drug release behavior. In this work, porous hollow microspheres of amorphous calcium phosphate have been successfully prepared by the microwave-assisted hydrothermal method using adenosine triphosphate disodium salt, CaCl and soybean lecithin in aqueous solution.

Microwave-assisted rapid synthesis of magnesium phosphate hydrate nanosheets and their application in drug delivery and protein adsorption.

Magnesium phosphate biomaterial, as an alternative to well-known calcium phosphate biomaterials, is an excellent candidate for biomedical applications, owing to its outstanding biocompatibility and biodegradability. Herein, we report a simple strategy for the rapid synthesis of magnesium phosphate hydrate nanosheets (MPHSs) using the microwave-assisted hydrothermal method. This method is facile, rapid, surfactant-free and environmentally friendly.

Porous microspheres of amorphous calcium phosphate: block copolymer templated microwave-assisted hydrothermal synthesis and application in drug delivery.

Amorphous calcium phosphate (ACP) microspheres with a porous and hollow structure have been prepared using an aqueous solution containing CaCl2 as a calcium source, adenosine triphosphate disodium salt (Na2ATP) as a phosphorus source in the presence of a block copolymer methoxyl poly(ethylene glycol)-block-poly(D,L-lactide) (mPEG-PLA) by the microwave-assisted hydrothermal method. The effects of microwave hydrothermal temperature and the concentrations of CaCl2 and Na2ATP on the crystal phase and morphology of the product are investigated. The as-prepared ACP porous hollow microspheres have a relatively high specific surface area of 232.

Multifunctional biodegradable mesoporous microspheres of Eu-doped amorphous calcium phosphate: microwave-assisted preparation, pH-sensitive drug release, and bioimaging application.

Biodegradable inorganic mesoporous materials hold promise for various biomedical applications such as drug/gene delivery, bioimaging, and photodynamic/photothermal and ultrasound therapy. Herein, multifunctional mesoporous microspheres of europium-doped amorphous calcium phosphate (Eu-doped ACP) have been prepared using a natural biomolecule adenosine triphosphate (ATP) by the rapid microwave-assisted solvothermal method. This method has advantages such as surfactant-free, rapid and energy-saving.

Amorphous calcium phosphate nanospheres/polylactide composite coated tantalum scaffold: facile preparation, fast biomineralization and subchondral bone defect repair application.

Calcium phosphate (CaP) materials are widely used in various biomedical areas such as drug/gene delivery and bone repair/tissue engineering. In this study, amorphous CaP nanospheres synthesized by a simple co-precipitation method are used to prepare the CaP-polylactide (CaP-PLA) composite. Then, the as-prepared CaP-PLA composite is used to coat tantalum (Ta) plates and porous scaffolds.

Core-shell hollow microspheres of magnetic iron oxide@amorphous calcium phosphate: synthesis using adenosine 5'-triphosphate and application in pH-responsive drug delivery.

Drug nanocarriers with magnetic targeting and pH-responsive drug-release behavior are promising for applications in controlled drug delivery. Magnetic iron oxides show excellent magnetism, but their application in drug delivery is limited by low drug-loading capacity and poor control over drug release. Herein, core-shell hollow microspheres of magnetic iron oxide@amorphous calcium phosphate (MIO@ACP) were prepared and investigated as magnetic, pH-responsive drug nanocarriers.

Solvothermal transformation of a calcium oleate precursor into large-sized highly ordered arrays of ultralong hydroxyapatite microtubes.

Hydroxyapatite (HAP), a well-known member of the calcium phosphate family, is the major inorganic component of bones and teeth in vertebrates. The highly ordered arrays of HAP structures are of great significance for hard tissue repair and for understanding the formation mechanisms of bones and teeth. However, the synthesis of highly ordered HAP structure arrays remains a great challenge.

ATP-stabilized amorphous calcium carbonate nanospheres and their application in protein adsorption.

Calcium carbonate is a common substance found in rocks worldwide, and is the main biomineral formed in shells of marine organisms and snails, pearls and eggshells. Amorphous calcium carbonate (ACC) is the least stable polymorph of calcium carbonate, which is so unstable under normal conditions that it is difficult to be prepared in vitro because it rapidly crystallizes to form one of the more stable polymorphs in aqueous solution. Herein, we report the successful synthesis of highly stable ACC nanospheres in vitro using adenosine 5'-triphosphate disodium salt (ATP) as a stabilizer.

Chitosan-coated mesoporous microspheres of calcium silicate hydrate: environmentally friendly synthesis and application as a highly efficient adsorbent for heavy metal ions.

Chitosan-coated calcium silicate hydrate (CSH/chitosan) mesoporous microspheres formed by self-assembly of nanosheets have been synthesized in aqueous solution under ambient conditions without using any toxic surfactant or organic solvent. The method reported herein has advantages of simplicity, low cost and being environmentally friendly. The BET specific surface area of CSH/chitosan mesoporous microspheres is measured to be as high as ~356 m(2) g(-1), which is considerably high among calcium silicate materials.

Highly flexible and nonflammable inorganic hydroxyapatite paper.

A highly flexible and nonflammable inorganic hydroxyapatite (HAP) paper made from HAP ultralong nanowires is reported. The paper can be used for printing and writing and is promising for the permanent and safe storage of information, such as archives and important documents. The HAP paper is also an excellent and recyclable adsorbent for organic pollutants.

Hydroxyapatite nanosheet-assembled microspheres: hemoglobin-templated synthesis and adsorption for heavy metal ions.

Hydroxyapatite (HAP) nanostructures have wide potential applications in many fields such as drug delivery, tissue engineering, bone repair, gas sensing, catalysis and water treatment. Inspired with the fact that HAP has a high affinity with proteins, we have designed and developed a new synthetic strategy for three-dimensional (3-D) HAP nanosheet-assembled microspheres (HAP-NMSs) by employing hemoglobin as a soft template. The as-prepared products are characterized by X-ray powder diffraction (XRD) and field-emission scanning electron microscopy (SEM).