Hydroxyapatite Sheets Research Articles

ZIF8/hydroxyapatite sheets: A sustainable triple-ligand MOF-based nanocarrier for enhancing the self-healing capabilities of the epoxy composite

A triple ligand metal organic framework (MOF) (named mix@HA/Z8) was designed and used as a smart anti-corrosion filler benzotriazole (BTA) and zinc nitrate were loaded into the pH-sensitive, highly resistant, and thermally stable Z8 nanocarriers. These nanocarriers were subsequently applied to the hydroxyapatite sheets to enhance the self-healing capabilities of the epoxy coating. This addition not only improved the barrier capability of the coating but also enhanced its self-healing nature. In order to validate the successful synthesis of the smart inhibitor, several tests such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and Transmission electron microscopy (TEM) were conducted. Additionally, Brunauer, Emmett, and Teller (BET) and Inductively Coupled Plasma (ICP) experiments were carried out to verify the appropriate loading and release of the inhibitor. The polarization and EIS experiments conducted to assess the anti-corrosion performance in the solution phase revealed that the mix@HA/Z8 had the best corrosion inhibition (51%) among the other samples. Furthermore, the EIS test for the intact coating containing the mix@HA/Z8 after 56 days of exposure to 3.5% saline solution demonstrated its ability to maintain log|Z|f = 0.01Hz higher than 1010.5 Ω cm2. FE-SEM testing of the scratched coating containing mix@HA/Z8 (after 48 h of immersion) confirmed its remarkable self-healing feature. The enhancement of the adhesion of mix@HA/Z8, as demonstrated by the pull-off analysis, indicated that the adhesion loss of the mix sample was lower than that of other coatings, standing at 21.21%.

Effect of process parameters on the synthesis and lead ions removal performance of novel porous hydroxyapatite sheets prepared via non-aqueous precipitation method

Herein, porous hydroxyapatite sheets with high lead ions removal performance are synthesized via self-assembly non-aqueous precipitation method, and the effects of process parameters on the synthesis and lead ions removal performance are systematically investigated. The optimized precursors concentration, the molar ratio of calcium to phosphorus and the calcination temperature are 0.25 mol/L, 1.67 and 650 °C, respectively. The refinement XRD, FE-SEM and EDS tests of the optimized samples show that the samples have a porous sheet structure with uniform pore size and wall thickness. The lead ions removal rate of hydroxyapatite sheets has the maximum value of 99.6% when the hydroxyapatite addition amount is 1 g/L. The lead ions removal content is the maximum of 1303.6 mg/g when the initial lead ions concentration is 9 mmol/L. The removal mechanism of lead ions by porous hydroxyapatite sheets prepared in this work is the composite mechanisms of surface adsorption, surface complexation and ions exchange. The hydroxyapatite porous sheet material prepared by optimizing the process parameters in this study has the advantages of high removal capacity and wide adaptability, so it is expected to become a novel adsorbent to solve lead-containing wastewater.

Preparation of novel porous hydroxyapatite sheets with high Pb2+ adsorption properties by self-assembly non-aqueous precipitation method

Herein, novel porous hydroxyapatite sheets with high pore homogeneity are prepared via a self-assembly nonaqueous precipitation method. The optimized calcium source, phosphorus source and solvent are calcium acetate, disodium hydrogen phosphate and glycerin, respectively. Hexagonal plate-like hydroxyapatite polycrystals form in the replacement-rearrangement groups of raw materials and grow along the (002) crystal plane of the hydroxyapatite phase. Large hydroxyapatite sheets have homogeneous pore sizes of approximately 110 nm and thicknesses of approximately 20 nm. The hydroxyapatite sheets prepared via the nonaqueous precipitation method are highly active carbonate apatite. In a nonaqueous environment, assembly units of hexagonal plate-like hydroxyapatite polycrystals are triggered by the replacement and rearrangement of groups in the raw materials, and they self-assemble to form large hydroxyapatite sheets in the form of edge sharing. The degree of curvature in the process of plate-like hydroxyapatite self-assembly triggers the formation of porous hydroxyapatite sheets. This material has excellent adsorption performance for Pb2+ ions. The material developed in this work has wide application prospects in the fields of adsorption treatment of wastewater containing toxic ions (such as Pb2+), and it is expected to become a novel type of lead ion adsorbent.

Corrosion self-diagnosing and self-repairing polymeric coatings based on zeolitic imidazolate framework decorated hydroxyapatite nanocontainer on steel

• Novel ZIF decorated HA nanocontainer with stimulus responsiveness were developed. • Encapsulation of Phen in nanocontainer can be easily achieved by one-step method. • Localized corrosion can be timely and precisely located and reported. • Coating exhibits barrier, corrosion self-diagnosing and self-repairing traits. Polymeric coatings with long life, strong environmental adaptability and high durability are of great significance for practical applications. This work presents a facial strategy to construct a smart nanocomposite coating with excellent shielding, corrosion self-diagnosing and self-repairing functions by integrating nanocontainers into epoxy resin. The nanocontainers were synthesized through decorating the hydroxyapatite sheets with zeolitic imidazolate frameworks (HA-ZIF), which were employed to encapsulate corrosion probe (Phenanthroline, Phen). With the occurrence of localized corrosion, Phen molecules could be timely released and reacted with the metal ions to form conspicuous red color at damaged sites, achieving real time corrosion diagnosing function. Given the stimulus responsive property of ZIF, the corrosion propagating process can be significantly inhibited by the released benzimidazole. As contrast of the traditional nanocontainers applied in anticorrosion coating, the inhibitors were used directly to synthesis the HA-ZIF nanocontainer rather than subsequent loading, which greatly improved inhibitors content in nanocontainers. Moreover, the impermeability of composite coating has been remarkably enhanced by the presence of HA sheets, ensuring the long-term protective performance. Importantly, the integrating multi functions in one coating is realized in the ingeniously designed nanocontainers. It is envisioned that the facial and feasible strategy provides insights in improving the longevity, functionality and reliability of protective coatings.

Crack Propagation and Toughening Mechanism of Staggered Structure of Hydroxyapatite Sheets

Based on the macro-microscopic analysis of the fracture path of cortical bone, it is shown that the crack path of the cortical bone deflected obviously during bending fracture, which indicates that the microstructure of the cortical bone affects the crack propagation of the bone. According to the microstructure of cortical bone, a staggered structure analysis model of hydroxyapatite (HA) sheets was established, and the effects of the structural parameters and volume content of hydroxyapatite sheets on the crack deflection coefficient and fracture toughness were compared and analyzed. The analysis results show that the structural parameters and volume fraction of hydroxyapatite sheets are positively correlated with the fracture toughness of bone. When the bone is fractured, the cracks deflected between the staggered hydroxyapatite layers to dissipate more energy, thereby improving the fracture toughness of the bone. The research results can provide useful guidance for the design and manufacture of high-performance bionic bone composites.

Development of Ultra-Thin Opaque White Hydroxyapatite Sheet for Restoration of Enamel and Aesthetic Treatments of Teeth

In cosmetic dentistry, bleaching and laminate veneer methods are common treatments to improve the appearance of teeth. However, there are limitations to these treatments, as they damage the enamel which are not capable of recovering naturally. In this study, novel hydroxyapatite (HAp) sheets, which enable both enamel restoration and aesthetic treatments, were developed. Results indicated that the lower range of the sintering temperatures, of the pulsed laser deposition targets, produced lighter shades of amorphous Calcium phosphate (ACP) sheets. Subsequently, the post-annealing process of the sheets induced crystallization processes of the ACP sheets, to form HAp sheets, and improved the shade rank of the sheet. The shade rank of the developed sheet (6.8 ± 0.2) was almost comparable to the average shade rank of the teeth of Japanese people, within a range of 6.5 to 7.0.

Preparation of ultrathin opaque white hydroxyapatite sheets and their aesthetic effects

Preparation of ultrathin opaque white hydroxyapatite sheets and their aesthetic effects

Optimal Conditions for Aqueous Tape Casting of Hydroxyapatite

An aqueous tape casting process was employed to produce hydroxyapatite (HA) sheets. The effects of viscosity of slurry, blade height and speed on flexural strength and density of the sintered HA sheets were studied using central composite design (CCD). The flexural strength and the density were measured using a three-point bending test and Archimedes method, respectively. Results suggested that all parameters and the interaction between viscosity and speed had significant effects on both flexural strength and density. Under the conditions studied, the optimal conditions for the maximum flexural strength and density of the sintered HA sheet were obtained with the viscosity of 1532 mPa.s, the blade height of 3.34 mm and the speed of 6.27 mm/s.

Control of Crystallinity of Hydroxyapatite Sheet

A technique to control the crystallinity of hydroxyapatite (HA) was investigated for applications such as dentistry, regenerative medicine, cell culture scaffolding, and bio-sensors. An amorphous HA film was first produced by pulsed laser deposition. After deposition, it was separated from a substrate as a free-standing sheet. Annealing was then performed to control the crystallinity of the sheet. It was found that conventional annealing in an electric oven was not suitable for HA sheets, because it led to curling and cracking. Since such problems were assumed to be caused by thermal stress, annealing was next carried out with the HA sheet enclosed in HA powder in the center of a metal capsule. This method allowed annealing to be successfully carried out without causing any curling or cracking. Uniform pieces with dimensions of 10 mm × 10 mm cut from a large HA sheet were annealed at temperatures of 200 to 800 ºC and then examined using X-ray diffraction. It was found that the intensity of the diffraction peaks associated with crystalline HA changed with annealing temperature, and that the strongest peaks were observed for the sample annealed at 500 ºC. These results indicate that the crystallinity of the HA sheet can be controlled using the proposed method.

Interlaced Microstructures of Bone

The observation of scanning electron microscope (SEM) shows that a tibia bone is a kind of bioceramic composite consisting of hydroxyapatite layers and collagen protein matters. The hydroxyapatite layers are composed of hydroxyapatite sheets. The observation also shows there is a kind of interlaced microstructure of the hydroxyapatite sheets. The maximum pullout force of the interlaced microstructure was investigated and compared with that of the parallel microstructure. It is indicated that the maximum pullout force of the interlaced microstructure with a large interlaced angle is markedly larger than that of the parallel microstructure.

Mechanism of Large Elastic Modulus of Bone

Scanning electron microscope (SEM) observation shows that fibula bone is a kind of bioceramic composite consisting of hydroxyapatite layers and protein matters. The hydroxyapatite layers are further composed of hydroxyapatite sheets. The observation also shows that the hydroxyapatite sheets possess quite large volume fraction and also have very long and thin fiber shape. The mechanism of the large volume fraction of the hydroxyapatite sheets to ensure the larger elastic modulus of the bone was investigated based on the model of the bone composite and the theory of the composite mechanics. The investigated result reveals that the large volume fraction of the hydroxyapatite sheets endows the bone with large elastic modulus.

Microstructure and Toughness Mechanism of Tooth

Tooth is a kind of biomaterial in nature. It behaves favorable strength, stiffness and fracture toughness, which are closely related to its fine microstructure. The observation of scanning electron microscope (SEM) on a mature tooth shows that the tooth is a kind of natural bioceramic composite consisting of hydroxyapatite layers and collagen protein matrix. The observation also shows that the hydroxyapatite layers consist of long and thin hydroxyapatite sheets and that all the hydroxyapatite sheets are arranged in a kind of parallel distribution. The maximum pullout energy of the hydroxyapatite sheets, which is closely related to the fracture toughness of the tooth, is investigated based on the representative model of the parallel distribution. It shows that the long and thin shape as well as the parallel distribution of the hydroxyapatite sheets increase the maximum pullout energy and enhance the fracture toughness of the tooth.

Intercrossed Microstructures of Hydroxyapatite Sheets of Tibia Bone

The observation of scanning electron microscope (SEM) showed that a tibia bone is a kind of bioceramic composite consisting of hydroxyapatite layers and collagen protein matrix. All the hydroxyapatite layers are parallel with the surface of the bone and consist of numerous hydroxyapatite sheets. The observation also showed there is a kind of intercrossed microstructure of the hydroxyapatite sheets. In which the hydroxyapatite sheets in an arbitrary hydroxyapatite layer make a large intercrossed angle with the hydroxyapatite sheets in its adjacent hydroxyapatite layers. The maximum pullout force of the intercrossed microstructure, which is closely related to the fracture toughness of the bone, was investigated and compared with that of the parallel microstructure of the sheets through their representative models. Result indicated that the maximum pullout force of the intercrossed microstructure is markedly larger than that of the parallel microstructure.

Helicoidal-Rounded-Hole Microstructure of Mature Shankbone

Scanning electron microscope (SEM) observation on a mature shankbone shows that the bone is a kind of bioceramic composite consisting of hydroxyapatite sheets and collagen protein matrix. The observation also shows that there are many holes in the bone and that the hydroxyapatite sheets near by these holes helicoidally round these holes forming a kind of helicoidally-rounded-hole microstructure (HRHM). The maximum pullout force of the HRHM is investigated and compared with that of non-helicoidally-rounded-hole microstructure (NHRHM). It shows that the HRHM could markedly increase the maximum pullout force of the hydroxyapatite sheets compared to the NHRHM and therefore enhance the fracture toughness of the bone.

Intercrossed Microstructures of Hydroxyapatite Sheets of Tibia Bone

The observation of Scanning Electron Microscope (SEM) shows that a tibia bone is a kind of bioceramic composite consisting of hydroxyapatite layers and collagen protein matrix. All the hydroxyapatite layers are parallel with the surface of the bone and consist of numerous hydroxyapatite sheets. The observation also shows that there is a kind of intercrossed microstructure of the hydroxyapatite sheets. In this kind of microstructure, the hydroxyapatite sheets in an arbitrary hydroxyapatite layer make a large intercrossed angle with the hydroxyapatite sheets in their adjacent hydroxyapatite layers. The maximum pullout force of the intercrossed microstructure, which is closely related to the fracture toughness of the bone, is investigated and compared with that of the parallel microstructure of the sheets through their representative models. The result of the investigation indicates that the maximum pullout force of the intercrossed microstructure is markedly larger than that of the parallel microstructure, which is experimentally verified.

Screwy microstructure of hydroxyapatite sheets of shank bone

Scanning electron microscope (SEM) observation shows that a shank bone is a kind of bioceramic composite consisting of inorganic hydroxyapatite and organic collagen protein. The hydroxyapatite possesses laminated microstructure and the each hydroxyapatite layer is composed of numerous long and thin hydroxyapatite sheets. The hydroxyapatite sheets in an arbitrary hydroxyapatite layer make an almost fixed angle with the hydroxyapatite sheets in their adjacent hydroxyapatite layers which compose a kind of particular screwy microstructure. The maximum pullout energy of the screwy microstructure, which is closely related to the fracture toughness of the bone, is theoretically investigated and compared with that of the parallel microstructure of the sheets. It shows that the maximum pullout energy of the screwy microstructure is markedly larger than that of the parallel microstructure, which is experimentally verified.

Nanostructure and Properties of a Shinbone

Scanning electron microscope (SEM) observation shows that a shinbone is composed of large-volume-fraction hydroxyapatite and small-volume-fraction collagen protein materials. The hydroxyapatite is of laminated structure and consists of numberless hydroxyapatite sheets. The observation also shows that the hydroxyapatite sheets are parallel with each other and of nanometer scale. The high fracture toughness and fracture strength of the bone are investigated based on the calculation formula of the dissipation work and Griffith criterion. The investigated results reveal that the large-volume fraction and the nanometer scale of the hydroxyapatite sheets are the important factors to the high mechanical performance of the bone.

INTERSECTANT MICROSTRUCTURE OF HYDROXYAPATITE SHEETS OF SHANKBONE

Bone possesses excellent mechanical properties, which are closely related to its favorable microstructures optimized by nature through millions of years. In this work, a scanning electron microscope (SEM) was used to observe the microstructures of a shankbone. It showed that the bone is a kind of bioceramic composite consisting of hydroxyapatite layers and collagen protein matrix. The hydroxyapatite layers are further composed of long and thin hydroxyapatite sheets. The hydroxyapatite sheets in different hydroxyapatite layers distribute along different orientations, which composes a kind of intersectant microstructure. The maximum pullout force of the intersectant microstructure was investigated and compared with that of 0° microstructure with their representative models. The result indicated that the maximum pullout force of the intersectant microstructure is markedly larger than that of the 0° microstructure, which was experimentally verified.

Toughness Analysis of Cannon Bone Based on Microstructural Model

As a typical biological material, bone possesses high fracture strength and fracture toughness, which are closely related to its exquisite microstructure. SEM observation of a cannon bone shows that the bone is a kind of layered bioceramic composite consisting of hydroxyapatite sheets and collagen matrix. The hydroxyapatite sheets are of long and thin shape, distributing in parallel. The fracture toughness of the bone is analyzed with the representative model of the hydroxyapatite sheets and the concept of maximum pullout energy. It is shown that the lathy shape as well as the parallel distribution of the hydroxyapatite sheets increases the pullout energy and endows the bone with high fracture toughness.

Hydroxyapatite-Sheet Microstructure of Shinbone

Bone is a kind of biomaterial in nature. It behaves favorable strength, stiffness and fracture toughness which are closely related to its fine microstructures. Scanning electron microscope (SEM) observation on a shinbone shows that the bone is a kind of natural bioceramic composite consisting of hydroxyapatite layers and collagen matrix. The hydroxyapatite layers are arranged in a parallel distribution and consist of many hydroxyapatite sheets. The fracture toughness of the bone was analyzed based on the representative model of the microstructure in the bone and the idea of maximum pullout energy. The analytical result shows that the long and thin shape as well as the parallel distribution of the hydroxyapatite sheets increase the maximum pullout energy of the sheets and enhance the fracture toughness of the bone.