Frontiers of Materials Science最新文献

Pore characteristics have been identified as key design parameters for osteoimmunomodulation. The strategy reported here is to create an appropriate immune microenvironment by regulating pore characteristics of scaffolds, thereby promoting early angiogenesis and enhancing osteogenesis. A series of collagen/nanohydroxyapatite (Col/nHAP) composite scaffolds with ordered lamellar structures and different layer spacings were prepared by mimicking the ordered lamellar topology of the bone matrix. Our research indicated that the layer spacing and ordered topology of the scaffold exerted an important influence on phenotype transformation of macrophages and the secretion of angiogenic factors. The Col/nHAP-O(135) with large layer spacing not only supported cell attachment and diffusion in vitro, but also promoted early angiogenesis by timely switching from M1 to M2 macrophage phenotype. In vivo data showed that the layer spacing and the ordered structure of the scaffold synergistically regulated the inflammatory response and triggered macrophages to secrete more angiogenesis related cytokines. Col/nHAP-O(135) considerably promoted the neovascularization and new bone formation in the defect site, indicating that Col/nHAP-O(135) could significantly enhance the osteogenic activity of stem cells with the involvement of macrophages.

Uncontrolled hemorrhage resulting from traumas causes severe health risks. There is an urgent need for expeditious hemostatic materials to treat bleeding incidents. Here, we developed a natural protein-based hemostatic sponge extracted from nonmulberry cocoons that exhibited rapid coagulation and effective absorption. We first built a degumming and dissolution system suitable for the Dictyoploca japonica cocoons to obtain regenerated silk fibroin (DSF). The DSF was then combined with carboxymethyl chitosan (CMCS) by glutaraldehyde (GA) crosslinking to ensure the structural stability of sponges. The resulting DSF–CMCS–GA exhibited remarkable hemostatic properties, displaying the highest absorption rate. It also demonstrated comparable efficacy to commercial hemostatic sponges. The blood-clotting index and hemolysis test showed that the prepared sponge possessed hemostatic activity and good hemocompatibility. Compared with mulberry silk fibroin hemostatic sponges (SF–CMCS–GA), DSF–CMCS–GA showed slightly better effects, making them a potential alternative to mulberry silk. In conclusion, our study introduces the use of Dictyoploca japonica silk fibroin for hemostasis, highlighting the exploitation of wild silkworm resources and providing an excellent silk fibroin-based hemostatic sealant for acute accident wounds and biomedical applications involving massive hemorrhage.

Tin dioxide nanotubes with N-doped carbon layer (SnO₂/N-C NTs) were synthesized through a MoO₃ nanorod-based sacrificial template method, dopamine polymerization and calcination process. Applied to the Li-ion battery, SnO₂/N-C NTs exhibited excellent electrochemical properties, with a first discharge capacity of 1722.3 mAh·g⁻¹ at 0.1 A·g⁻¹ and a high capacity of 1369.3 mAh·g⁻¹ over 100 cycles. The superior electrochemical performance is ascribed to the N-doped carbon layer and tubular structure, which effectively improves the electrical conductivity of the composites, accelerates the migration of Li⁺ and electrons, and alleviates the volume change of the anode to a certain extent.

Herein, a novel visible-light-responsive photocatalyst with high efficiency was firstly synthesized at room temperature. The mild synthetic method resulted in a uniform spherical triazine-based covalent organic framework (TrCOF2) with ultra-high specific surface area as well as chemical stability. Due to the synergistic effect between the self-assembled uniform spherical structure and the abundant triazine-based structure, photoelectron–hole pairs were efficiently separated and migrated on the catalysts. On this basis, TrCOF2 was successfully applied to efficiently degrade bisphenol A (BPA). More than 98% of BPA was deraded after 60 min of visible light treatment, where the active specie of •O ⁻₂ played a vital role during the degradation of BPA. The holes of TrCOF2 could produce O₂ by direct reaction with water or hydroxide ions. Simultaneously, photoelectrons can be captured by O₂ to generate •O ⁻₂ . Moreover, density functional theory (DFT) calculations proved the outstanding ability of the exciting electronic conductivity. Remarkably, a reasonable photocatalytic mechanism for TrCOF2 catalysts was proposed. This research can provide a facile strategy for the synthesis of TrCOFs catalysts at room temperature, which unfolds broad application prospects in the environmental field.

Flexible humidity sensors are widely used in many fields, such as environmental monitoring, agricultural soil moisture content determination, food quality monitoring and healthcare services. Therefore, it is essential to measure humidity accurately and reliably in different conditions. Flexible materials have been the focusing substrates of humidity sensors because of their rich surface chemical properties and structural designability. In addition, flexible materials have superior ductility for different conditions. In this review, we have summarized several sensing mechanisms, processing techniques, sensing layers and substrates for specific humidity sensing requirements. Aadditionally, we have sorted out some cases of flexible humidity sensors based on different functional materials. We hope this paper can contribute to the development of flexible humidity sensors in the future.

Flexible strain sensors have been extensively used in human motion detection, medical aids, electronic skins, and other civilian or military fields. Conventional strain sensors made of metal or semiconductor materials suffer from insufficient stretchability and sensitivity, imposing severe constraints on their utilization in wearable devices. Herein, we design a flexible strain sensor based on biphasic hydrogel via an in-situ polymerization method, which possesses superior electrical response and mechanical performance. External stress could prompt the formation of conductive microchannels within the biphasic hydrogel, which originates from the interaction between the conductive water phase and the insulating oil phase. The device performance could be optimized by carefully regulating the volume ratio of the oil/water phase. Consequently, the flexible strain sensor with oil phase ratio of 80% demonstrates the best sensitivity with gauge factor of 33 upon a compressive strain range of 10%, remarkable electrical stability of 100 cycles, and rapid resistance response of 190 ms. Furthermore, the human motions could be monitored by this flexible strain sensor, thereby highlighting its potential for seamless integration into wearable devices.

As a structural and functional material with excellent properties, ceramics play an extremely important role in a wide range of industries, including life and production. To expand the range of applications for ceramic materials, ceramics are often joined to metals and then used. Among the physical and chemical joining methods of ceramics to metals, the AMB method is efficient and simple, suitable for industrial applications, and has been a hot topic of research. However, due to the problems of residual stresses caused by the large difference in thermal expansion coefficients between ceramic and metal brazing, composite fillers have become a very worthwhile solution by regulating the physical properties of the brazing material and improving the weld structure. This review describes the wetting principle and application of Ag-Cu-Ti active metal filler in the field of ceramic joining, with emphasis on the current stage of composite filler, and discusses the influence on the former brazing properties and organization after the introduction of dissimilar materials.

It is still a challenge to prepare a water- and polymer-based electrospun air filter film with high efficiency filtration, low pressure drop, and good mechanical properties. To address this issue, polyvinyl alcohol (PVA) was employed as the main material, mixing polyethyleneimine (PEI), bamboo-based activated carbon (BAC) and cellulose nanocrystal (CNC) to construct the air filter film by electrostatic electrospinning. In this system, the negatively charged BAC and CNC are fixed in the system through bonding with the positively charged PEI, showing a double adsorption effect. One is the mechanical filtration of the porous network structure constructed by PVA@PEI electrospun nanofibers, and the other is the electrostatic adsorption of PM2.5 on the surface of BAC and CNC. It is significant that the resulting composite air filter displays a high filtration efficiency of 95.86%, a pressure drop of only 59 Pa, and good thermal stability. Moreover, the introduced methyltrimethoxysilane (MTMS) endows it with good water-resistance. Given these excellent performances, this system can provide theoretical and technical references for the development of water- and polymer-based electrospun air filter film.

Few-layers WS₂ was obtained through unique chemical liquid exfoliation of commercial WS₂. Results showed that after the exfoliation process, the thickness of WS₂ reduced significantly. Moreover, the NiFe₂O₄ nanosheets/WS₂ composite was successfully synthesized through a facile hydrothermal method at 180 °C, and then proven by the analyses of field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The composite showed a high specific surface area of 86.89 m²·g⁻¹ with an average pore size of 3.13 nm. Besides, in the three-electrode electrochemical test, this composite exhibited a high specific capacitance of 878.04 F·g⁻¹ at a current density of 1 A·g⁻¹, while in the two-electrode system, the energy density of the composite could reach 25.47 Wh·kg⁻¹ at the power density of 70 W·kg⁻¹ and maintained 13.42 Wh·kg⁻¹ at the higher power density of 7000 W·kg⁻¹. All the excellent electrochemical performances demonstrate that the NiFe₂O₄ nanosheets/WS₂ composite is an excellent candidate for supercapacitor applications.

Among various metal chalcogenides, metal oxides and phases of copper sulfide, copper(II) sulfide (covellite, CuS) nanostructures have enjoyed special attentiveness from researchers and scientists across the world owing to their complicated structure, peculiar composition and valency, attractive and panoramic morphologies, optical and electrical conductivity, less toxicity, and biocompatibility that can be exploited in advanced and technological applications. This review paper presents a brief idea about crystal structure, composition, and various chemical methods. The mechanism and effect of reaction parameters on the evolution of versatile and attractive morphologies have been described. Physical properties of CuS and its hybrid nanostructures, such as morphology and optical, mechanical, electrical, thermal, and thermoelectrical properties, have been carefully reviewed. A concise account of CuS and its hybrid nanostructures’ diverse applications in emerging and recent applications such as energy storage devices (lithium-ion batteries, supercapacitance), sensors, field emission, photovoltaic cells, organic pollutant removal, electromagnetic wave absorption, and emerging biomedical field (drug delivery, photothermal ablation, deoxyribonucleic acid detection, anti-microbial and theranostic) has also been elucidated. Finally, the prospects, scope, and challenges of CuS nanostructures have been discussed precisely.