Ultralong Hydroxyapatite Nanowires Research Articles

Organic-Inorganic Dual-Network Composite Separators for Lithium Metal Batteries.

The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic-inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m-phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote "ion flow redistribution." The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li+ conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19µm-thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68mS cm-1) and a high lithium-ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO4||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1C and demonstrates impressive rate capability with a discharge capacity of 72.7mAh g-1 at 15C.

Biomimetic Scaffolds Regulating the Iron Homeostasis for Remolding Infected Osteogenic Microenvironment.

The treatment of infected bone defects (IBDs) needs simultaneous elimination of infection and acceleration of bone regeneration. One mechanism that hinders the regeneration of IBDs is the iron competition between pathogens and host cells, leading to an iron deficient microenvironment that impairs the innate immune responses. In this work, an in situ modification strategy is proposed for printing iron-active multifunctional scaffolds with iron homeostasis regulation ability for treating IBDs. As a proof-of-concept, ultralong hydroxyapatite (HA) nanowires are modified through in situ growth of a layer of iron gallate (FeGA) followed by incorporation in the poly(lactic-co-glycolic acid) (PLGA) matrix to print biomimetic PLGA based composite scaffolds containing FeGA modified HA nanowires (FeGA-HA@PLGA). The photothermal effect of FeGA endows the scaffolds with excellent antibacterial activity. The released iron ions from the FeGA-HA@PLGA help restore the iron homeostasis microenvironment, thereby promoting anti-inflammatory, angiogenesis and osteogenic differentiation. The transcriptomic analysis shows that FeGA-HA@PLGA scaffolds exert anti-inflammatory and pro-osteogenic differentiation by activating NF-κB, MAPK and PI3K-AKT signaling pathways. Animal experiments confirm the excellent bone repair performance of FeGA-HA@PLGA scaffolds for IBDs, suggesting the promising prospect of iron homeostasis regulation therapy in future clinical applications.

A review of the prospects, efficacy and sustainability of nanotechnology-based approaches for oil spill remediation.

Numerous marine oil spill incidents and their environmental catastrophe have raised the concern of the research community and environmental agencies on the topic of the offshore crude oil spill. The oil transport through oil tankers and pipelines has further aggravated the risk of the oil spill. This has led to the necessity to develop an effective, environment-friendly, versatile oil spill clean-up strategy. The current review article analyses various nanotechnology-based methods for marine oil spill clean-up, focusing on their recovery rate, reusability and cost. The authors weighed the three primary factors recovery, reusability and cost distinctively for the analysis based on their significance in various contexts. The findings and analysis suggest that magnetic nanomaterials and nano-sorbent have been the most effective nanotechnology-based marine oil spill remediation techniques, with the magnetic paper based on ultralong hydroxyapatite nanowires standing out with a recovery rate of over 99%. The chitosan-silica hybrid nano-sorbent and multi-wall carbon nanotubes are also promising options with high recovery rates of up to 95-98% and the ability to be reused multiple times. Although the photocatalytic biodegradation approach and the nano-dispersion method do not offer benefits for recovery or reusability, they can nevertheless help lessen the negative ecological effects of marine oil spills. Therefore, careful evaluation and selection of the most appropriate method for each marine oil spill situation is crucial. The current review article provides valuable insights into the current state of nanotechnology-based marine oil spill clean-up methods and their potential applications.

Bottom-Up Assembling Hierarchical Enamel-Like Bulk Materials with Excellent Optical and Mechanical Properties for Tooth Restoration.

Enamel has good optical and mechanical properties because of its multiscale hierarchical structure. Biomimetic construction of enamel-like 3D bulk materials at nano-, micro-, mesh- and macro-levels is a challenge. A novel facile, cost-effective, and easy large-scale bottom-up assembly strategy to align 1D hydroxyapatite (HA) nanowires bundles to 3D hierarchical enamel structure with the nanowires bundles layer-by-layer interweaving orientation, is reported. In the strategy, the surface of oleate templated ultralong HA nanowires with a large aspect ratio is functionalized with amphiphilic 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Furtherly, the MDP functionalized HA nanowire bundles are assembled layer-by-layer with oriented fibers in a single layer and cross-locked between layers at a certain angle at mesoscale and macroscale in the viscous bisphenol A-glycidyl methacrylate (Bis-GMA) ethanol solution by shear force induced by simple agitation and high-speed centrifugation. Finally, the excessive Bis-GMA and ethanol are removed, and (Bis-GMA)-(MDP-HA nanowire bundle) matrix is densely packed under hot pressing and polymerized to form bulk enamel-like materials. The composite has superior optical properties and comparable comprehensive mechanic performances through a combination of strength, hardness, toughness, and friction. This method may open new avenues for controlling the nanowires assembly to develop hierarchical nanomaterials with superior properties for many different applications.

Biomimetically ordered ultralong hydroxyapatite nanowires-based hierarchical hydrogel scaffold with osteoimmunomodulatory and osteogenesis abilities for augmenting bone regeneration

Artificial construction of tissue engineering implants with bone-mimicking structure and osteogenic function is of great significance for bone regeneration, but it remains a formidable challenge. Herein, inspired by natural bone, a biomimetically hierarchical hydrogel scaffold with highly ordered arrangement and multi-layered concentric circular structure is constructed by a convenient free-injection method for osteoimmunomodulation and bone defect regeneration. Ultralong hydroxyapatite nanowires act as skeleton unit to assemble into the hierarchically ordered nanowire bundles and further hybridization with hyaluronic acid methacrylate and loading with layered double hydroxide nanosheets to form the stable biomimetic scaffold. The biomimetic scaffold exhibits anisotropic structure, high water content and porosity, mechanical robustness, and sustained release of bioactive ions. In particular, the excellent biocompatibility together with ordered topography and biochemical cue can guide recruitment and directional migration of stem cells, and effectively promote osteogenic differentiation and vascularization in vitro. Moreover, the biomimetic scaffold induces M2 phenotype polarization of macrophages, thus creating a favorable osteoimmune environment. The in vivo study proves that the biomimetic scaffold can attenuate inflammation, promote vascularized ossification, and further accelerate new bone formation. This study provides an innovative strategy to construct multifunctional anisotropic biomaterials for bone tissue engineering.

Enhanced Osteogenic Differentiation Based on Combining Pulp Stem Cells with Ultralong Hydroxyapatite Nanowires and Cellulose Fibers

Previous studies have confirmed the excellent biocompatibility, osteogenic properties, and angiogenic ability of hydroxyapatite (HAP), as well as the good osteoblast differentiation ability of dental pulp stem cells. We hypothesized that combining dental pulp stem cells with ultralong hydroxyapatite nanowires and cellulose fibers could more effectively promote osteoblast differentiation, making it a potential biomaterial for enhancing bone wound healing. Therefore, based on the optimal ratio of ultralong hydroxyapatite nanowires and cellulose fibers (HAPNW/CF) determined in previous studies, we added human dental pulp stem cells (hDPSCs) to investigate whether this combination can accelerate cell osteogenic differentiation. hDPSCs were introduced into HAPNW/CF scaffolds, and in vitro experiments revealed that: (1) HAPNW/CF scaffolds exhibited no cytotoxicity toward hDPSCs; (2) HAPNW/CF scaffolds enhanced alkaline phosphatase staining activity, an early marker of osteogenic differentiation, and significantly upregulated the expression level of osteogenic-related proteins; (3) co-culturing with hDPSCs in HAPNW/CF scaffolds significantly increased the expression of angiogenesis-related factors compared to hDPSCs alone when tested using human umbilical vein endothelial cells (hUVECs). Our study demonstrates that combining hDPSCs with HAPNW/CF can enhance osteogenic differentiation more effectively, potentially through increased secretion of angiogenesis-related factors promoting osteoblast differentiation.

Salt-rejecting 3D cone flowing evaporator based on bilayer photothermal paper for high-performance solar seawater desalination

Solar energy-driven water evaporation technology is a promising, low-cost and sustainable approach to alleviate the global clean water shortage, but usually suffers from low water evaporation rate and severe salt deposition on the water evaporation surface. In this work, a hydrophilic bilayer photothermal paper-based three-dimensional (3D) cone flowing evaporator was designed and prepared for stable high-performance seawater desalination with excellent salt-rejecting ability. The as-prepared bilayer photothermal paper consisted of MXene (Ti3C2Tx) and HAA (ultralong hydroxyapatite nanowires, poly(acrylic acid), and poly(acrylic acid-2-hydroxyethyl ester)). The accordion-like multilayered MXene acted as the efficient solar light absorber, and ultralong hydroxyapatite (HAP) nanowires served as the thermally insulating and supporting skeleton with a porous networked structure. A siphon effect-driven unidirectional fluid transportation unit in the 3D cone flowing evaporator could guide the concentrated saline flowing away from the evaporating surface to prevent salt deposition on the evaporation surface, avoiding severe deterioration of the performance in solar water evaporation. Furthermore, combining high solar light absorption and high photothermal conversion efficiencies, low water evaporation enthalpy (1838 ± 11 J g−1), and additional energy taken from the ambient environment, the as-prepared cone flowing evaporator exhibited a high water evaporation rate of 3.22 ± 0.20 kg m−2 h−1 for real seawater under one sun illumination (1 kW m−2), which was significantly higher than many values reported in the literature. This study provides an effective approach for designing high-performance solar energy-driven water evaporators for sustainable seawater desalination and wastewater purification.

A composite dressing combining ultralong hydroxyapatite nanowire bio-paper and a calcium alginate hydrogel accelerates wound healing.

An acute wound is the most common type of skin injury. Developing wound dressings with excellent mechanical properties, wound protection, comfort, angiogenic capacity and therapeutic effects is significant for effective treatments, yet remains challenging. Herein, we have designed a novel HAP-Alg composite dressing comprising a complementary ultralong hydroxyapatite (HAP) nanowire bio-paper and calcium alginate hydrogel. The HAP bio-paper assembled by ultralong HAP nanowires, in contrast to typical brittle HAP bio-ceramics, exhibits a highly flexible and interwoven structure to enhance the mechanical and protective performance of an alginate hydrogel, and the alginate matrix creates a moist environment for skin regeneration. Therefore, the HAP-Alg composite dressing presents good mechanical properties and high resistance to swelling and shrinkage, along with a reliable bacterial shielding ability. In addition, its moisturizing effect can deliver bioactive calcium ions to promote angiogenesis, accelerate re-epithelialization and reduce scar formation. In vitro studies reveal that the HAP-Alg composite dressing has excellent biocompatibility, promotes cell migration and angiogenesis, and enhances calcium ion influx. In vivo wound models further prove the ability of the HAP-Alg composite dressing to accelerate wound closure, enhance collagen deposition, and induce neovascularization. This work demonstrates that the HAP-Alg composite dressing offers a promising wound dressing for acute wound treatment and protection.

Bone-inspired hydroxyapatite nanowire-based bioceramics with superior mechanical performance

The fabrication of hydroxyapatite (HAP)-based bioceramics with similar mechanical performance to bone by traditional sintering process is still challenge. In bone tissues, HAP mineralized collagen fibrils and fiber-oriented microstructure play key roles in superior mechanical performance of bone. Inspired by the fiber-oriented microstructure and biomineralization process of bone, the mineralized HAP-based bioceramics (M-HAP) are successfully fabricated via directional assembly and biomimetic mineralization strategies based on ultralong HAP nanowires. The M-HAP bioceramics show comparable mechanical performance to human cortical bone in terms of flexural strength, tensile strength, Young's modulus and hardness, which could overcome the issue of mismatched mechanical properties between traditional HAP implants and host bone. In addition, the M-HAP bioceramics also exhibit good cytocompatibility in vitro and no obvious inflammatory response after implantation in vivo. Such bone-inspired bioceramics with both high mechanical property and good biocompatibility have great potential in the field of bone regeneration.

Ultralong hydroxyapatite nanowires-based flow-through reactor with high loading of silver nanoparticles for fast continuous catalytic reduction of organic dyes and disinfection of wastewater

The noble metal nanoparticles (NPs) immobilized flow-through reactors have attracted significant attention for the continuous and efficient purification of wastewater contaminated with organic dyes and microorganisms without the need of subsequent recycling processes. However, achieving both high loading of noble metal NPs and high permeation flux concurrently has been a challenge for most reported flow-through reactors. In this study, inspired by the mussel bio-adhesion strategy, we have employed the tannic acid coating method and successfully synthesized Ag NPs-loaded ultralong hydroxyapatite (HAP) nanowires that exhibited an ultra-high loading amount (21.8 wt%). These nanowires were utilized as building blocks alongside chitosan (CS) to fabricate robust and highly porous flow-through reactors (Ag@HAP/CS) for continuous catalytic reduction of organic dyes and water disinfection. The Ag@HAP/CS reactor demonstrates excellent catalytic reduction efficiency (99.3 %) towards MEB at a high flux (2000 L m−2 h−1) with an extremely low concentration of NaBH4 (MEB:NaBH4 = 1:1). This result is attributed to the high loading of Ag NPs, great structural stability in flowing water, and sufficient length along the flowing direction. The reactor also shows remarkable recyclability through water flushing. Ag@HAP/CS exhibits remarkable water disinfection performance against Escherichia coli and diverse bacteria in natural river water, achieving nearly 100 % disinfecting efficiency. This study provides new insights into the strategy of using nanomaterials as intermediate carriers of noble metal nanoparticles to fabricate 3D flow-through reactors, which enable fast and continuous purification of wastewater with ultra-high catalytic efficiency and antimicrobial performance.

Ultralong hydroxyapatite nanowires-incorporated dipeptide hydrogel with enhanced mechanical strength and superior in vivo osteogenesis activity

Self-assembling peptide hydrogels have attracted considerable interest in tissue engineering for their biocompatibility, biodegradability, low immunogenicity, facile modification, and similarity to the native extracellular matrix. However, they still suffer from weak mechanical strength and lack of specific bioactivity. Ultralong hydroxyapatite nanowires (UHANWs) are synthesized to work as a reinforcement agent similar to the steel bars in the reinforced concrete to co-assemble with dipeptide nanofibers, endowing the hybrid hydrogel with enhancing and controllable mechanical properties. Furthermore, additional factors BMP-2 can be introduced into the hydrogel to improve its bioactivity. The experimental results show that the incorporation of UHANWs into the hydrogel matrix leads to an obvious increase in the storage modulus of scaffolds, exhibiting good biocompatibility and bioactivity. The hybrid hydrogels can facilitate the proliferation and osteogenetic differentiation of cells on their surface. The in vivo evaluation reveals that bone defects implanted with the as-designed hydrogel scaffolds show enhanced bone regeneration activity, implying their great potential in biomedical fields.

Bioinspired Aerogel with Vertically Ordered Channels and Low Water Evaporation Enthalpy for High-Efficiency Salt-Rejecting Solar Seawater Desalination and Wastewater Purification.

Solar energy-driven water evaporation is a promising sustainable strategy to purify seawater and contaminated water. However, developing solar evaporators with high water evaporation rates and excellent salt resistance still faces a great challenge. Herein, inspired by the long-range ordered structure and water transportation capability of lotus stem, a biomimetic aerogel with vertically ordered channels and low water evaporation enthalpy for high-efficiency solar energy-driven salt-resistant seawater desalination and wastewater purification is developed. The biomimetic aerogel consists of ultralong hydroxyapatite nanowires as heat-insulating skeletons, polydopamine-modified MXene as a photothermal material with broadband sunlight absorption and high photothermal conversion efficiency, polyacrylamide, and polyvinyl alcohol as reagents to lower the water evaporation enthalpy and as glues to enhance the mechanical performance. The honeycomb porous structure, unidirectionally aligned microchannels, and nanowire/nanosheet/polymer pore wall endow the biomimetic aerogel with excellent mechanical properties, rapid water transportation, and excellent solar water evaporation performance. The biomimetic aerogel exhibits a high water evaporation rate (2.62kgm-2 h-1 ) and energy efficiency (93.6%) under one sun irradiation. The superior salt-rejecting ability of the designed water evaporator enables stable and continuous seawater desalination, which is promising for application in water purification to mitigate the global water crisis.

Influence of Solvothermal Reaction Temperature on Hydroxyapatite Nanowires

Nowadays, nanomaterials have become the focus of many scientific researchers. As one of the mostly used biomaterials, the special structure and good performance of hydroxyapatite (HA) nanowires is a research hotspot. However, the synthesis of ultralong HA nanowires with highly efficiency and relatively low-cost is still a great challenge. In this work, HA nanowires are successfully synthesized through a simple solvothermal route, with calcium oleate and sodium hexametaphosphate as the calcium and phosphorus source, respectively. Influence of the solvothermal reaction temperature on the HA products are investigated. As the solvothermal temperature increases, the morphology of the HA crystals become nanowires and the length increases. This method is one-step and environmentally friendly without any pollution, since no organic solvent is allowed to be used in the whole experiment. The as-synthesized ultralong HA nanowires have enhanced mechanical properties and can be used in bone tissue engineering, drug delivery, adsorbents, and many other applications.

Wet End Chemical Properties of a New Kind of Fire-Resistant Paper Pulp Based on Ultralong Hydroxyapatite Nanowires.

In 2014, a new type of the fire-resistant paper based on ultralong hydroxyapatite (HAP) nanowires was reported by the author’s research group, which had superior properties and promising applications in various fields, such as high-temperature resistance, fire retardance, heat insulation, electrical insulation, energy, environmental protection, and biomedicine. The wet end chemical properties of the fire-resistant paper pulp are very important for papermaking and mechanical performance of the paper, which play a guiding role in the practical production of the fire-resistant paper. In this paper, the wet end chemical properties of a new kind of fire-resistant paper pulp based on ultralong HAP nanowires are studied for the first time by focusing on the wet end chemical parameters, the effects of these parameters on the properties such as flocculation, retention, draining, and white water circulation of the fire-resistant paper pulp, and their effects on the properties of the as-prepared fire-resistant paper. The experimental results indicated that the wet end chemical properties of the new kind of fire-resistant paper pulp based on ultralong HAP nanowires were unique and entirely different from those of the traditional paper pulp based on plant fibers. The wet end chemical properties of the fire-resistant paper pulp were significantly influenced by the inorganic adhesive and its content, which affected the runnability of the paper machine and the properties of the as-prepared fire-resistant paper. The flocculation properties of the fire-resistant paper pulp based on ultralong HAP nanowires were affected by the conductivity and Zeta potential. The addition of the inorganic adhesive in the fire-resistant paper pulp based on ultralong HAP nanowires could significantly increase the conductivity of the fire-resistant paper pulp, reduce the particle size of paper pulp floccules, and increase the tensile strength of the fire-resistant paper. In addition, the fire-resistant paper pulp based on ultralong HAP nanowires in the presence of inorganic adhesive exhibited excellent antibacterial performance. This work will contribute to and accelerate the commercialization process and applications of the new type of the fire-resistant paper based on ultralong HAP nanowires.

Skeleton-inspired optical-selective cellulose-based bio-film as passive radiative cooler and the energy-saving performance evaluation

To alleviate the energy consumption and CO2 emission caused by the operation of electrical equipment in hot weather, passive radiative cooling (PRC) has been considered as an effective strategy owing to the non-power input and non-pollution. In spite of exciting process, PRC materials are still limited by the poor optical selectivity in practical applications. Herein, inspired by the potential optical-thermal properties of the porous structure and composition of skeleton, ultra-thin hydrophobic sodium alginate (SA) cellulose bio-film was designed including precisely 3D porous structure like skeleton and ultra-long hydroxyapatite nanowires (HAP ULNWs) as self-assembled supporting frame. The obtained bio-film could reflect>95.59 % of solar radiation only within ultra-thin scale (∼220 μm) as well as emit 96.73 % of thermal radiation. As the proof, the bio-film was used for the outdoor radiative cooling and about 12℃ maximum cooling effect could be obtained during the daytime under high solar radiation power density (>1750 W/m2). For evaluating the energy-saving potential, a building model covered with PRC film was established and 48.67 % of average electric energy consumption could be saved per year in China. The work presents an alternative strategy to enhance the optical selectivity and may facilitate the high-performance cooling energy saving.

Microwave-Assisted Hydrothermal Rapid Synthesis of Ultralong Hydroxyapatite Nanowires Using Adenosine 5'-Triphosphate.

Ultralong hydroxyapatite (HAP) nanowires are promising for various biomedical applications owing to their chemical similarity to the inorganic constituent of bone, high biocompatibility, good flexibility, excellent mechanical properties, etc. However, it is still challenging to control the formation of ultralong HAP nanowires because of the presence of free PO43− ions in the reaction system containing the inorganic phosphate source. In addition, it takes a long period of time (usually tens of hours) for the synthetic process of ultralong HAP nanowires. Herein, for the first time, we have developed an eco-friendly calcium oleate precursor microwave hydrothermal method using biocompatible adenosine 5′-triphosphate (ATP) as a bio-phosphorus source and water as the only solvent for the rapid synthesis of ultralong HAP nanowires. The controllable hydrolysis of ATP can avoid the premature formation of calcium phosphate nuclei and uncontrollable crystal growth. Microwave heating can significantly shorten the synthetic time from tens of hours required by the traditional heating to 1 h, thus achieving high efficiency, energy saving and low cost. The as-prepared ultralong HAP nanowires with high flexibility have lengths of several hundred micrometers and diameters of 10~20 nm, and they usually self-assemble into nanowire bundles along their longitudinal direction. The as-prepared ultralong HAP nanowire/chitosan porous scaffold has excellent bioactivity, good biodegradation and cytocompatibility owing to the bioactive adenosine adsorbed on the surface of ultralong HAP nanowires. It is expected that ultralong HAP nanowires will be promising for various applications in the biomedical fields, such as bone defect repair, skin wound healing, and as a drug nanocarrier.

Assembly of Ultralong Hydroxyapatite Nanowires into Enamel-like Materials

To develop dental restorative materials with enamel-like structures, ultralong hydroxyapatite (HA) nanowires were synthesized by a hydrothermal method, followed by functionalization with 3-methacryloxypropyltrimethoxysilane (KH-570). The mixture of HA nanowires, KH-570, and light initiator was stirred and centrifuged. The precipitate was vacuum filtered to remove excessive KH-570 and then pressured under cold isostatic pressing (10 MPa × 24 h). Finally, the block was polymerized by lighting. Scanning electron microscopy and transmission electron microscopy showed that HA nanowires with aspect ratios >1,000 were assembled into enamel rod–like microstructures and evenly dispersed in the polymerized KH-570 silane matrix to form enamel-like structures. Thermogravimetric analysis demonstrated that the content of HA nanowires reached 72 wt% in the composite. The enamel-like composite showed a similar hardness, frictional property, and acid-etching property to those of enamel and a comparable or even better diametral tensile strength and compressive strength than some commercial composite resins in mechanical tests in vitro. In addition, the enamel-like composite had good cytocompatibility. Such enamel-like composites may have the potential to be used in biomimetic tooth restorations in the future.

Flexible nanocomposite paper with superior fire retardance, mechanical properties and electrical insulation by engineering ultralong hydroxyapatite nanowires and aramid nanofibers

With the increasing popularity of modern electronic devices in the fifth-generation (5G) era, high-performance and high-safety electrically insulating materials with good mechanical flexibility and strength, high thermal stability and fire resistance are urgently needed. Herein, we report a highly flexible, thermally stable, and fire-retardant nanocomposite paper with high dielectric breakdown strength and mechanical strength by synergistically integrating one-dimensional ultralong hydroxyapatite (HAP) nanowires and aramid nanofibers (ANFs) through the vacuum-assisted filtration process. The as-prepared HAP/ANF nanocomposite paper has a nanowire/nanofiber networked framework and a layered structure, and exhibits high tensile strength (73.5 MPa), fracture strain (7.4 %), folding durability (1396 times under a loading weight of 9.8 N), excellent flexibility, and good processibility. Notably, the HAP/ANF nanocomposite paper has a superior dielectric breakdown strength (92.4 kV mm−1), high thermal stability and flame retardancy in comparison with the commercial Nomex T410 electrical insulation paper. The multifunctional HAP/ANF nanocomposite paper is promising for applications in miniaturized and flexible electronic devices, high-voltage electrical insulation equipments, and fire-retardant and high-temperature fields.

Biopaper Based on Ultralong Hydroxyapatite Nanowires and Cellulose Fibers Promotes Skin Wound Healing by Inducing Angiogenesis

Skin injury that is difficult to heal caused by various factors remains a major clinical challenge. Hydroxyapatite (HAP) has high potential for wound healing owing to its high biocompatibility and adequate angiogenic ability, while traditional HAP materials are not suitable for wound dressing due to their high brittleness and poor mechanical properties. To address this challenge, we developed a novel wound dressing made of flexible ultralong HAP nanowire-based biopaper. This biopaper is flexible and superhydrophilic, with suitable tensile strength (2.57 MPa), high porosity (77%), and adequate specific surface area (36.84 m2·g−1) and can continuously release Ca2+ ions to promote the healing of skin wounds. Experiments in vitro and in vivo show that the ultralong HAP nanowire-based biopaper can effectively induce human umbilical vein endothelial cells (HUVECs) treated with hypoxia and rat skin tissue to produce more angiogenic factors. The as-prepared biopaper can also enhance the proliferation, migration, and in vitro angiogenesis of HUVECs. In addition, the biopaper can promote the rat skin to achieve thicker skin re-epithelialization and the formation of new blood vessels, and thus promote the healing of the wound. Therefore, the ultralong HAP nanowire-based biopaper has the potential to be a safe and effective wound dressing and has significant clinical application prospects.

Flexible photothermal biopaper comprising Cu2+-doped ultralong hydroxyapatite nanowires and black phosphorus nanosheets for accelerated healing of infected wound

Cutaneous wounds accompanied by bacterial infections and impaired angiogenesis might be lethal and remain a challenging issue in clinical fields, causing an urgent need for the multifunctional wound dressings with effective disinfection and wound tissue regenerative abilities. Herein, we report a flexible photothermal biopaper (named BP/HAP:Cu2+) with the integration of two-dimensional photothermal-capable black phosphorus nanosheets (BPNSs) and one-dimensional antibacterial Cu2+-doped ultralong hydroxyapaptite (HAP:Cu2+) nanowires for accelerated healing of the infected wound. The as-prepared BP/HAP:Cu2+ biopaper exhibits the stable porous networked structure, high porosity, good biocompatibility, superior photothermal conversion ability and antibacterial function. The photothermal effect generated by BPNSs conjugated with the sustained release of Cu2+ ions can damage the bacterial membrane and enhance glutathione oxidation, achieving a synergistic high antibacterial efficiency on Staphylococcus aureus of 97.0%. Moreover, the BP/HAP:Cu2+ biopaper can effectively promote in vitro angiogenesis of human umbilical vein endothelial cells. Results of animal experiments further reveal that the BP/HAP:Cu2+ biopaper as the wound dressing under near infrared laser irradiation significantly enhances the wound healing by simultaneously eliminating bacteria and accelerating angiogenesis. Taken together, the BP/HAP:Cu2+ photothermal biopaper has a promising therapeutic potential for rapid healing of infected wounds.