Hydroxyapatite Nanowires Research Articles

Multiscale engineered artificial tooth enamel.

Tooth enamel, renowned for its high stiffness, hardness, and viscoelasticity, is an ideal model for designing biomimetic materials, but accurate replication of complex hierarchical organization of high-performance biomaterials in scalable abiological composites is challenging. We engineered an enamel analog with the essential hierarchical structure at multiple scales through assembly of amorphous intergranular phase (AIP)-coated hydroxyapatite nanowires intertwined with polyvinyl alcohol. The nanocomposite simultaneously exhibited high stiffness, hardness, strength, viscoelasticity, and toughness, exceeding the properties of enamel and previously manufactured bulk enamel-inspired materials. The presence of AIP, polymer confinement, and strong interfacial adhesion are all needed for high mechanical performance. This multiscale design is suitable for scalable production of high-performance materials.

Construction of coral rod-like MoS2@HA nanowires hybrids for highly effective green antisepsis

Antibacterial materials have been rapidly emerging as a primary component in the mitigation of bacterial pathogens, and green functional materials play a vital role in the antibacterial field. In this study, biocompatible hydroxyapatite nanowires (HANW) was used as a carrier, a coral rod-like nanowires hybrid of MoS2 and HANW (CR-MoS2@HANW) was synthesized via a facile two-step hydrothermal approach. After being characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmet-Teller (BET) and thermogravimetric (TG) analysis, the antibacterial activity and environmental compatibility were assessed. It was found that MoS2 nanosheets were in-situ assembled onto surface of HA nanowires, and the obtained nanohybrid exhibited excellent stability. CR-MoS2@HANW endowed a desirable long-term antibacterial activity against both gram-negative E. coli and gram-positive S. aureus. It was sufficient to inhibit the growth of bacteria within 72 h, and nanohybrids effectively promoted the growth of plants. In summary, the combination of MoS2 and HANW created a novel eco-friendly nanohybrids that could be applied as a promising multi-functional green antisepsis. And the CR-MoS2@HANW possessed enormous potential for biomedical applications.

Novel inorganic fillers of 1D hydroxyapatite nanowires induced superior energy storage performances of P(VDF–HFP)-based composite films

Newly one-dimensional hydroxyapatite nanowires are synthesized and applied in P(VDF–HFP) nanocomposites for energy storage application. Excellent Ud of ∼27.6 J cm−3 accompanied with high η of ∼72.9% at Eb of 650 MV m−1 are achieved.

A scalable, low-cost and green strategy for the synthesis of ultralong hydroxyapatite nanowires using peanut oil

A scalable green and low-cost synthesis of ultralong hydroxyapatite nanowires using peanut oil is reported, which can be scaled up for large-scale low-cost production of ultralong hydroxyapatite nanowires and the fire-resistant inorganic paper.

Carbon dots-decorated hydroxyapatite nanowires-lanthanide metal-organic framework composites as fluorescent sensors for the detection of dopamine.

In this work, carbon dots-decorated hydroxyapatite nanowires-lanthanide metal-organic framework composites were designed and synthesized as ratiometric fluorescent probes for the detection of dopamine. The as-prepared HAPNWs-CDs-Tb/MOF were characterized by TEM, FE-SEM, and FT-IR spectral analysis, illustrating that the HAPNWs-CDs-Tb/MOF comprised hydroxyapatite nanowires that acted as a carrier to form a spinning structure of the lanthanide MOF that was decorated with carbon dots. The as-prepared HAPNWs-CDs-Tb/MOF were luminescent with the green fluorescence of Tb3+ at 543 nm and the blue fluorescence of the CDs at 426 nm as the signal response groups for the detection of DA. The sensor could detect DA in the concentration range of 0-180 μM, with a linear range of 0.04-20 μM and detection limit of 12.26 nM. The method was successfully applied to the detection of DA in human serum. The spiked recoveries were 100.8%-103.3% and the relative standard deviation (RSD) was 3.82%.

Flexible Photothermal Biopaper Comprising Cu <sup>2+</sup>-Doped Ultralong Hydroxyapatite Nanowires and Black Phosphorus Nanosheets for Accelerated Healing of Infected Wound

Flexible Photothermal Biopaper Comprising Cu <sup>2+</sup>-Doped Ultralong Hydroxyapatite Nanowires and Black Phosphorus Nanosheets for Accelerated Healing of Infected Wound

The preparation of hydroxyapatite nanowires and nanorodsviaaliphatic micelles as soft templates

Hydroxyapatite nanoparticles were tunably synthesizedviathe use of an aliphatic–ethanol–water three-phase mixture system using micelles as soft templatesviaan emulsion–hydrothermal synergistic method.

Osteogenic Property Regulation of Stem Cells by a Hydroxyapatite 3D-Hybrid Scaffold With Cancellous Bone Structure

Cancellous bone plays an indispensable role in the skeletal system due to its various functions and high porosity. In this work, chitosan and hydroxyapatite nanowires (CS@HAP NWs) hybrid nanostructured scaffolds with suitable mechanical properties, high porosity and a fine porous structure were prepared to simulate the 3-dimensional structure of cancellous bone. The 3D-hybrid scaffolds promote cell adhesion and the migration of human adipose-derived stem cells (hADSCs) inside the scaffolds. The cavities in the scaffolds provide space for the hADSCs proliferation and differentiation. Moreover, the various contents of HAP and the induced mechanical property changes regulate the differentiation of hADSCs toward osteoblasts. Overall, cellular fate regulation of hADSCs via rationally engineered HAP-based hybrid scaffolds is a facile and effective approach for bone tissue engineering.

Tree‐Inspired Ultralong Hydroxyapatite Nanowires‐Based Multifunctional Aerogel with Vertically Aligned Channels for Continuous Flow Catalysis, Water Disinfection, and Solar Energy‐Driven Water Purification

AbstractWater pollution and freshwater shortage have deteriorated the global water crisis. Developing sustainable methods to alleviate contaminated water has become an urgent affair. Herein, inspired by water transportation and transpiration of natural trees, the authors report an ultralong hydroxyapatite nanowires‐based biomimetic aerogel with vertically aligned channels and multiple functions for continuous flow catalysis, water disinfection, solar energy‐driven water purification, and seawater desalination. Ultralong hydroxyapatite nanowires act as carriers to immobilize catalyst nanoparticles and serve as building blocks to assemble with chitosan to form the biomimetic aerogel with structure‐function integration. Benefiting from the interconnected cellular structure, unidirectional aligned channels, nanowire‐interwoven networked pore wall, and evenly distributed catalyst nanoparticles, the biomimetic aerogel exhibits high catalytic activity (97.6% treatment efficiency) and permeability (1786 L m−2 h−1), excellent recyclability and stability in continuous flow catalytic degradation of methylene blue solely driven by gravity. The biomimetic aerogel exhibits excellent performance for bacteria removal and anti‐biofouling. The superior photothermal conversion and heat confinement properties enable the biomimetic aerogel with a high efficiency (86.7%) for solar energy‐driven seawater desalination and wastewater purification under one sun irradiation. The multifunctional biomimetic aerogel has promising applications in catalytic reactions, wastewater remediation, and environmental engineering.

Composite films of hydroxyethyl cellulose and hydroxyapatite nanowires with high mechanical strength and electrical insulation property

An insulation network was constructed by adding hydroxyapatite nanowires (HNs) to a hydroxyethyl cellulose (HEC) system. The HNs improve the mechanical and insulating properties of the composites. The results showed the formation of strong chemical interactions between the HEC and HNs. Moreover, 20% HNs addition maximized the electrical insulation and tensile strength of the HEC/HNs film to 12.7 kV/mm and 34.12 MPa, respectively. Scanning electron microscopy revealed a three-dimensional network of HNs at the perforated edge of the films, which prevented further decomposition of HEC by the current flow. The superior mechanical properties of the combined HEC and HNs were attributed to the self-assembling cambium structure.

Rapidly Degrading Tetracycline by Highly Selective Catalysis with Hydroxyapatite Nanowire

Abstract Hydroxyapatite nanowire (HAnW), a novel synthesized biocompatible material without any transition metals, was applied to catalytic degradation of antibiotics. Importantly, tetracycline (TC), a common drug, could be rapidly adsorbed and catalytically degraded by HAnW, and the removal reached 85% within 5 min at room temperature.

An ultralong hydroxyapatite nanowire aerogel for rapid hemostasis and wound healing

Rapid hemostasis and wound healing for emergency trauma is the key to ensure the survival of patients with massive hemorrhage. However, it is still a challenge to develop hemostatic materials with both excellent hemostatic activity and wound healing function. Herein, we propose to fabricate an inorganic hemostatic aerogel mainly based on biocompatible inorganic ultralong hydroxyapatite (HAP) nanowires with polyvinyl alcohol (PVA) as organic binder, and the hemostatic aerogel is prepared by using freeze-drying technology to construct three-dimensional (3D) porous structure, which possesses good plasticity and flexibility. When the content of ultralong HAP nanowires reaches 80 wt%, the W-8HAP-2PVA aerogel (aerogel consists of 80 wt% ultralong HAP nanowires and 20 wt% PVA) exhibits super-hydrophilicity/super-hematophilicity, and its in vitro blood clotting index is only 3.81 ± 0.71 %, which is much lower than that of medical gauze. When applied in hemostasis of rat liver and rabbit femoral artery, the hemostatic time and blood loss amount of the W-8HAP-2PVA aerogel are 26.59 ± 7.46 s, 0.18 ± 0.05 g and 174.00 ± 16.57 s, 2.18 ± 1.56 g, respectively. Benefiting from its excellent hydrophilicity and high porosity structure, W-8HAP-2PVA aerogel can quickly absorb water from blood to concentrate blood cells and platelets and accelerate hemostasis. Notably, it shows good hemocompatibility and cytocompatibility, and is able to promote skin wound healing. Hence, W-8HAP-2PVA aerogel has great potential in rapid hemostasis and wound healing for clinical settings.

Nanofiltration membrane embedded with hydroxyapatite nanowires as interlayer towards enhanced separation performance

The triple-layered composite nanofiltration (NF) membrane consisting of thin polyamide (PA) top layer covered on polymeric porous membrane with interlayer has been popularly accepted, even commercially applied, to solve the “trade-off” issue. The nanofiltration performance was determined by the physicochemical properties of all layers. In the current work, hydroxyapatite (HAP) nanowires were adopted as a new type of interlayer material. Its superiority of ultra-hydrophilicity and electronegativity made it a container of aqueous monomers. As a result, ultra-thin and defect-free PA layer with a thickness of ~28 nm was generated owing to the low piperazine (PIP) concentration and restricted diffusion. In addition, the ultra-hydrophilic polysulfone (PSf) support layer was also helpful to reduce mass transfer resistance. The prepared PA/HAP/PSf composite membrane presented high salt aqueous solution permeation (177 L m −2 h −1 under 6 bar), excellent divalent salt rejection (98.2% for Na 2 SO 4 ) and high mono/bivalent salt selectivity (19 for NaCl/Na 2 SO 4 mixed solutions). This work proposed a useful strategy to construct highly permeable and selective NF membrane. PA/HAP/PSf triple-layered electronegative nanofiltration membrane showing high selectivity to monovalent/bivalent ions • HAP nanowires were adopted as interlayer of composite NF membrane for the first time. • The prepared PA/HAP/PSf NF membrane possessed ultra-thin and robust electronegative PA layer. • High rejection of 98.2% and salt permeation of 177 L m −2 h −1 under 6 bar for Na 2 SO 4 were achieved.

Multifunctional Fire‐Resistant Paper Based on Ultralong Hydroxyapatite Nanowires†

AbstractPaper was one of the greatest inventions in ancient China, and it greatly promoted the rapid development of human civilization. Even in today's electronic information age, paper and paper‐derived products are still indispensable to people's daily work and life. However, the traditional paper based on cellulose fibers from plants has some problems. For instance: (1) papermaking consumes a large amount of precious natural resources such as trees; (2) the papermaking industry causes environmental pollution; (3) the traditional paper consisting of organic cellulose fibers is highly flammable and easy to burn; (4) the traditional paper based on cellulose fibers turns to yellow color with time; (5) the lifetime of the traditional paper is relatively short because of the degradation of cellulose fibers. More efforts are needed to investigate and solve these problems facing the traditional paper. In recent years, a new kind of multifunctional fire‐resistant paper based on ultralong hydroxyapatite nanowires has been developed and investigated for various applications, and many research findings have been documented in the literature. This review article provides a comprehensive summary and discussion on recent research advances for this new kind of multifunctional fire‐resistant paper based on ultralong hydroxyapatite nanowires, including the synthesis, properties, applications, and future perspectives.

Biodegradable Elastic Sponge from Nanofibrous Biphasic Calcium Phosphate Ceramic as an Advanced Material for Regenerative Medicine

AbstractBiodegradable porous calcium phosphate (CaP) ceramics are widely used as synthetic graft substitutes for bone regeneration, owing to their chemical and structural similarity to bone and associated bioactivity in terms of bone‐bonding, osteoconductive, and even osteoinductive properties. Nevertheless, the intrinsic brittleness and poor processability of porous CaP ceramics strongly impair their clinical applicability. Herein, a biphasic calcium phosphate (BCP) sponge is developed that consists of a self‐supporting network of seamlessly interwoven hydroxyapatite nanowires and β‐tricalcium phosphate nanofibers and possesses a highly interconnected porous structure with open cell geometry and ultrahigh porosity. Owing to its unique properties, the ceramic sponge can be easily processed into various shapes and dimensions, such as cylindrical scaffolds and thin, flexible membranes. Moreover, the BCP sponge can be introduced into a bone defect in a compacted or folded state from a syringe and, upon wetting, expand to its original shape, thereby filling the cavity. The nanofibrous sponge gradually degrades in vitro and rapidly mineralizes when immersed in simulated body fluid. Moreover, it adsorbs significantly more proteins than a conventional porous BCP ceramic. Finally, the nanofibrous sponge supports the attachment, proliferation, and osteogenic differentiation of human mesenchymal stromal cells comparable to the conventional porous BCP ceramic.

Hydroxyapatite-reinforced alginate fibers with bioinspired dually aligned architectures

Biological materials have excellent mechanical properties due to their organized structures from nano- to macro-scale. Artificial manufacture of materials with anisotropic microstructures still remains challenging. We described a stress-induced method to fabricate anisotropic alginate fibers. Organic-inorganic composite fibers were obtained by incorporating aligned hydroxyapatite (HAP) nanowires into the alginate fiber. Detailed structural characterization revealed the bone-like structure of the HAP-reinforced alginate fibers. Tensile test results showed that the maximum Young's modulus and tensile strength were 4.3 GPa and 153.8 MPa, respectively. A multiscale reinforcing mechanism is proposed after the discussion of the structure-property relationship: highly ordered and compacted nanofibrils aligned along the longitudinal direction at the microscale, and two kinds of alginate gels with different mechanical behaviors at the nanoscale coexisted (acidic alginate gel and calcium-alginate gel). This work validates the effectiveness of the bioinspired fabrication strategy, which inspires further manufacturing and optimization of materials for diverse applications.

Bioceramic fibrous scaffolds built with calcium silicate/hydroxyapatite nanofibers showing advantages for bone regeneration

Bioceramic materials currently applied in bone repairing mainly base on calcium phosphate compounds like hydroxyapatite (HA), however, issues including slow degradation rate and insufficient bioactivity limit their efficiency in promoting bone regeneration. Calcium silicate (CS) is a promising alternative for the purpose thanks to its degradability and bioactive Si4+ release ability, while its fast degradation rate will cause pH problem and does not match the rhythm of osteogenesis. Herein, 3D composite bioceramic scaffolds were fabricated by blending different weight fractions (1:0, 3:1, 1:1, 1:3 or 0:1) of CS nanofibers (CSNFs) and HA nanowires (HANWs) via steps of fiber-dispersing, freeze-drying and sintering. With subsequent polymer coating, the porous structure and mechanical properties of the CSNF/HANW scaffolds were improved and scaffold performances were further regulated in dependence on the hydrophobicity/hydrophilicity and degradation rates of the polymers. Poly(l-lactide) (PLLA), poly(lactide-co-caprolactone) (PLCL) and gelatin were applied as the polymer coating. It was found that PLLA- and PLCL-coating would slow down the scaffold degradation and ion release rate compared to the gelatin-coating, while the increasing fraction of CSNFs would accelerate these events to increase medium pH due to the alkalinity of the bioceramic material. Finally, proliferation and osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) achieved desirable outcomes on gelatin-coated CSNF/HANW scaffolds with their fractions of 1:1 and 1:3, strongly suggesting the potential of these scaffolds for bone regeneration.

Multifunctional Ionic Skin with Sensing, UV‐Filtering, Water‐Retaining, and Anti‐Freezing Capabilities

AbstractConductive polymer hydrogels are receiving considerable attention in applications such as soft robots and human‐machine interfaces. Herein, a transparent and highly ionically conductive hydrogel that integrates sensing, UV‐filtering, water‐retaining, and anti‐freezing performances is achieved by the organic combination of tannic acid‐coated hydroxyapatite nanowires (TA@HAP NWs), polyvinyl alcohol (PVA) chains, ethylene glycol (EG), and metal ions. The highly ionic conductivity of the hydrogel enables tensile strain, pressure, and temperature sensing capabilities. In particular, in terms of the hydrogel strain sensors based on ionic conduction, it has high sensitivity (GF = 2.84) within a wide strain range (350%), high linearity (R2 = 0.99003), fast response (≈50 ms) and excellent cycle stability. In addition, the incorporated TA@HAP NWs act as a nano‐reinforced filler to improve the mechanical properties and confer a UV‐shielding ability upon the hydrogel due to its size effect and the characteristics of absorbing ultraviolet light waves, which can reflect and absorb short ultraviolet rays and transmit visible light. Meanwhile, owing to the water‐locking effect between EG and water molecules, the hydrogel exhibits freezing resistance at low temperatures and moisture retention at high temperatures. This biocompatible and multifunctional conductive hydrogel provides new ideas for the design of novel ionic skin devices.

In vivo behaviors of highly flexible paper consisting of ultralong hydroxyapatite nanowires.

This study was conducted in order to investigate biological compatibility of a thin and flexible hydroxyapatite (HAP) paper which consists of ultralong hydroxyapatite nanowires. Circular-shaped cranial bone defects with a diameter of 8.8 mm were prepared to expose the dura maters in Wistar rats. The similar-sized, circular-shaped HAP paper was placed at the bottom of the bone defects. After 2, 4, and 8 weeks, the rats were sacrificed, and the experimental sections were examined by micro-CT scanning and histological observation. The HAP paper covered with fibrous tissues showed no inflammatory cell infiltration, and their thicknesses decreased over time. Tartrate-resistant acid phosphatase-positive osteoclast-like cells were induced around the edges of the HAP paper along with the exfoliation of the HAP paper. The newly-formed bones were observed in the bone-defected areas, either with a direct contact with the HAP paper or through thin fibrous tissues. The HAP paper-induced osteoblast differentiation was confirmed since the alkaline phosphatase activities were detected on the surfaces of the HAP paper. These results indicated that the HAP paper may induce osteogenesis without causing any harmful effects. The highly flexible HAP paper can contribute to further development of bone regenerative therapy.

Customized Cellulose Fiber Paper Enabled by an In Situ Growth of Ultralong Hydroxyapatite Nanowires.

Cellulose fiber (CF) paper is a low-cost, sustainable, and flexible substrate, which has gained increasing interest recently. Before practical usage, the functionalization of the pristine CF paper is indispensable to meet requirements of specific applications. Different from conventional surface modification or physical mixing methods, we report in situ growth of ultralong hydroxyapatite nanowires (HAPNWs) with lengths larger than 10 μm on the CF paper. HAPNWs are radially aligned on the surface of CFs, creating a micro/nanoscale hierarchical structure. By means of the excellent ion exchange ability of HAP and the hierarchical structure, the functions of the CF paper can be easily customized. As a proof-of-concept, we demonstrate two kinds of functional CF paper: (1) the photoluminescent CF paper by doping Eu3+ and Tb3+ ions into the crystal lattice of HAPNWs and (2) the superhydrophobic CF paper by coating poly(dimethylsiloxane) on the HAPNW hierarchical structure, which can be applied for self-cleaning and oil/water separation. It is expected that an in situ growth of ultralong HAPNWs will provide an instructive guideline for designing a CF paper with specific functions.