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ABSTRACTMulti-material additive manufacturing (MMAM) takes full advantage of the ability to arbitrarily place materials of additive manufacturing technology, enabling immense design freedom and functional print capabilities. Among MMAM technologies, projection stereolithography (PSL) exhibits a great balance of high resolution and fast printing speed. However, fabrication accuracy of multi-material PSL is hindered by large overcure used to strengthen interfacial bonding weakened by chemical affinity and material-exchange process. We present a novel multi-step exposure method for multi-material PSL process to overcome this shortcoming. Firstly, the whole layer is moderately exposed producing overcure of single-material PSL level to generate geometries. Then weakened interfaces are strengthened individually with additional steps of exposure. The multi-step exposure is integrated into the already efficient materials printing order of multi-material PSL process. Curing depth and overcure of photocurable resins are modeled and characterized. Exposure required to achieve sufficient interfacial bonding of single-material interfaces built through material-exchange process and multi-material interfaces with altering materials printing order is determined with tensile tests. Microfluidic channels are used to compare fabrication accuracy of traditional single-step exposure and our multi-step exposure method. This method can be widely applied in multi-material PSL to improve fabrication accuracy in a variety of applications including microfluidic devices.

With the advancement of vehicle technology, there is a growing demand for vehicle comfort in addition to the focus on safety and functionality. On certain accident-prone sections of highways, such as entrance and exit ramps, tunnels, and downhill stretches, continuous speed bumps are typically installed to remind vehicles to reduce their speed. However, while enhancing safety, these measures also introduce a degree of discomfort for passengers and drivers alike. Vehicle speed and the type of road speed bump are key factors influencing vehicle comfort. In order to improve the ride comfort, this paper investigates the problem of adaptive speed control for vehicles passing over different types of continuous speed bumps and proposes a method for solving the optimal speed. In this research, a 4-degree-of-freedom vehicle suspension model and a road excitation model are employed to simulate vehicle vibrations. Simulation optimisation is performed using MATLAB in conjunction with an immune algorithm to obtain the optimal vehicle speeds for traversing three types of continuous speed bumps – sinusoidal, rectangular, and trapezoidal – while adhering to specified constraints. The simulation results demonstrate that this optimisation algorithm effectively enhances the ride comfort of vehicles when navigating speed bumps. The algorithm, when applied, reduces vehicle vertical displacement, acceleration, suspension deflection, and tyre load to varying degrees when crossing speed bumps. It also reduces tyre ground clearance to some extent, achieving a balance between comfort and safety. Furthermore, the study identifies the range of comfortable vehicle speeds for traversing these three types of speed bumps, providing valuable insights for selecting the appropriate speed bump design on roads with varying speed limits.

The multi-mode planar mechanisms (MMPMs) are excellent-performance reconfigurable mechanisms, which not only inherit structural characteristics of planar mechanisms but also have the multi-task, multi-working-condition application advantages of multi-mode mechanisms. However, lacking common bifurcation analysis and construction methods, their industrial application and development are seriously hindered. This paper presents a replaceable-component method to construct a set of single-degree-of-freedom (single-DOF) MMPMs based on the branch graphs of the corresponding planar mechanisms and the proposed multi-mode modules (MMMs). First, according to the established loop equations, all the kinematic information of the original planar mechanism is obtained by the branch graphs and singularity points using Maple. Then, compared to the relationship between the concepts of the branch and motion mode, the number and continuity of branches are taken as the index to identify the potential bifurcation and mode conversion ability for the corresponding planar mechanisms. Subsequently, the MMM is presented to help the planar mechanisms break the singularity positions to form the corresponding MMPMs, and the steps of constructing single-DOF MMPMs are summarized. Finally, a single-DOF Stephenson six-bar three-mode planar mechanism, a Watt six-bar three-mode planar mechanism, and an eight-bar four-mode planar mechanism are constructed for the first time, and the corresponding multi-mode motion analyses are made. The results can give the available configuration for the design of corresponding MMPMs. The proposed method will provide strong guidance for the configuration design of MMPMs.

Installation errors are important factor for the contact performance of the variable hyperbolic circular arc tooth trace (VH-CATT) cylindrical gear; the study of the relationship between installation errors and contact performances is beneficial for gear vibration and noise reduction. Firstly, based on the meshing theory, the tooth surface equation and contact ellipse of the VH-CATT cylindrical gear were deduced, and the tooth surface imprinting experiment was realized. Next, the tooth contact analysis model of the VH-CATT cylindrical gear was developed to investigate the influence of the installation errors on the elliptical contact area. Then, the calculation formulas of the tooth surface gap and contact point flexibility matrix were carried out to develop the load tooth contact analysis model of the VH-CATT cylindrical gear. Finally, the influence of the installation errors on the load distribution was investigated. Research shows that the elliptical contact area of the VH-CATT cylindrical gear is a line contact within a certain range and is located in the middle section of the tooth width. The elliptical contact area of the VH-CATT cylindrical gear increases or decreases rapidly when meshing in and out, and all the installation errors have a certain influence on the elliptical contact area, except for the center distance error. The single-tooth meshing area with the installation errors is greater than that of the ideal gear pair. The load distribution area with the installation errors deviates from the middle section, except for the center distance error. The installation rotation errors around the x and y axis have a certain influence on the maximum load of the single-tooth meshing area. The research results provide a basis for improving the bearing capacity of the VH-CATT cylindrical gear and optimizing the design.

In this work, a finite-element welding model of the X80 pipeline is established, and the residual stress is calculated using a direct thermal–mechanical coupling method through the User Material (UMAT) subroutine of the double-ellipsoid moving heat source. The effects of process parameters on the welding residual stress of the X80 pipelines are discussed. The ultrasonic longitudinal critical refraction (LCR) wave-detecting method is adopted to verify the simulation results. The results show that the residual stress at the inner surface is higher than that at the outer surface, and the peak Mises stress at the welding seam approaches the yield stress. With the increase in welding groove angle and heat input, the peak Mises stress increases at the inner surface and decreases at the outer surface, but the high-stress zone at the outer surface broadens. The residual stresses at the outer surface are more sensitive to the welding parameters. The comparison between the simulated results and ultrasonic LCR detection indicates that the finite-element method is feasible, and the simulation results are credible.

In order to deeply understand the cutting mechanism of SiCp / Al in ultrasonic vibration-assisted turning, a prediction model of a cutting temperature field of SiCp / Al composites in UVAC (ultrasonic vibration-assisted cutting) was established. A theoretical model of instantaneous cutting depth and transient shear angle was established considering the real-time changing cutting depth, tool front angle and shear angle characteristics of UVAC. The relationship between cutting speed, shear speed and chip flow speed in UVAC processes is revealed, as well as the shear force and the front cutter friction force. Finally, the influence of heat generated by the heat source zone and shear heat source zone on the temperature rise was calculated, and the temperature field model was established. The experiment of processing SiCp / Al composites by UVAC was carried out. SiCp / Al composites with 25 % volume fraction were turned, and the cutting temperature data were measured and recorded by an infrared thermal imaging device. The cutting speed, cutting depth and feed rate were tested by a single factor, and the changes in cutting temperature under different parameters were compared. Finally, the experimental data were compared with the theoretical values to verify the validity of the theoretical model.

Abstract All-inorganic lead halide perovskites (LHPs) and their use in optoelectronic devices have been widely explored because they are more thermally stable than their hybrid organic‒inorganic counterparts. However, the active perovskite phases of some inorganic LHPs are metastable at room temperature due to the critical structural tolerance factor. For example, black phase CsPbI3 is easily transformed back to the nonperovskite yellow phase at ambient temperature. Much attention has been paid to improving the phase stabilities of inorganic LHPs, especially those with high solar cell efficiencies. Herein, we discussed the origin of phase stability for CsPbI3 and the strategies used to stabilize the cubic (α) phase. We also assessed the CsPbI3 black β/γ phases that are relatively stable at nearly room temperature. Furthermore, we determined the relationship between phase stabilization and defect passivation and reviewed the growing trend in solar cell efficiency based on black phase CsPbI3. Finally, we provide perspectives for future research related to the quest for optimum device efficiency and green energy.

Abstract Metal-organic frameworks (MOF) are an attractive class of porous materials due to their immense design space, allowing for application-tailored properties. Properties of interest, such as gas sorption, can be predicted in silico with molecular mechanics simulations. However, the accuracy is limited by the available empirical force field and partial charge estimation scheme. In this work, we train a graph neural network for partial charge prediction via active learning based on Dropout Monte Carlo. We show that active learning significantly reduces the required amount of labeled MOFs to reach a target accuracy. The obtained model generalizes well to different distributions of MOFs and Zeolites. In addition, the uncertainty predictions of Dropout Monte Carlo enable reliable estimation of the mean absolute error for unseen MOFs. This work paves the way towards accurate molecular modeling of MOFs via next-generation potentials with machine learning predicted partial charges, supporting in-silico material design.

Abstract High-throughput materials research is strongly required to accelerate the development of safe and high energy-density lithium-ion battery (LIB) applicable to electric vehicle and energy storage system. The artificial intelligence, including machine learning with neural networks such as Boltzmann neural networks and convolutional neural networks (CNN), is a powerful tool to explore next-generation electrode materials and functional additives. In this paper, we develop a prediction model that classifies the major composition (e.g., 333, 523, 622, and 811) and different states (e.g., pristine, pre-cycled, and 100 times cycled) of various Li(Ni, Co, Mn)O2 (NCM) cathodes via CNN trained on scanning electron microscopy (SEM) images. Based on those results, our trained CNN model shows a high accuracy of 99.6% where the number of test set is 3840. In addition, the model can be applied to the case of untrained SEM data of NCM cathodes with functional electrolyte additives.

Abstract Uncertainty quantification (UQ) is rapidly becoming a sine qua non for all forms of computational science out of which actionable outcomes are anticipated. Much of the microscopic world of atoms and molecules has remained immune to these developments but due to the fundamental problems of reproducibility and reliability, it is essential that practitioners pay attention to the issues concerned. Here a UQ study is undertaken of classical molecular dynamics with a particular focus on uncertainties in the high-dimensional force-field parameters, which affect key quantities of interest, including material properties and binding free energy predictions in drug discovery and personalized medicine. Using scalable UQ methods based on active subspaces that invoke machine learning and Gaussian processes, the sensitivity of the input parameters is ranked. Our analyses reveal that the prediction uncertainty is dominated by a small number of the hundreds of interaction potential parameters within the force fields employed. This ranking highlights what forms of interaction control the prediction uncertainty and enables systematic improvements to be made in future optimizations of such parameters.

Abstract Protected surface states arising from non-trivial bandstructure topology in semimetals can potentially enable advanced device functionalities in compute, memory, interconnect, sensing, and communication. This necessitates a fundamental understanding of surface-state transport in nanoscale topological semimetals. Here, we investigate quantum transport in a prototypical topological semimetal NbAs to evaluate the potential of this class of materials for beyond-Cu interconnects in highly-scaled integrated circuits. Using density functional theory (DFT) coupled with non-equilibrium Green’s function (NEGF) calculations, we show that the resistance-area R A product in NbAs films decreases with decreasing thickness at the nanometer scale, in contrast to a nearly constant R A product in ideal Cu films. This anomalous scaling originates from the disproportionately large number of surface conduction states which dominate the ballistic conductance by up to 70% in NbAs thin films. We also show that this favorable R A scaling persists even in the presence of surface defects, in contrast to R A sharply increasing with reducing thickness for films of conventional metals, such as Cu, in the presence of surface defects. These results underscore the potential of topological semimetals as future back-end-of-line (BEOL) interconnect metals.

Abstract Magnetic Josephson junctions (MJJs) have emerged as a prominent playground to explore the interplay between superconductivity and ferromagnetism. A series of fascinating experiments have revealed striking phenomena at the superconductor/ferromagnet (S/F) interface, pointing to tunable phase transitions and to the generation of unconventional spin-triplet correlations. Here, we show that the Josephson effect, being sensitive to phase space variation on the nanoscale, allows a direct observation of the spin polarization of the S/F interface. By measuring the temperature dependence of the Josephson magnetic field patterns of tunnel MJJs with strong and thin F-layer, we demonstrate an induced nanoscale spin order in S along the superconducting coherence length at S/F interface, i.e., the inverse proximity effect, with the first evidence of full spin screening at very low temperatures, as expected by the theory. A comprehensive phase diagram for spin nanoscale ordering regimes at S/F interfaces in MJJs has been derived in terms of the magnetic moment induced in the S-layer. Our findings contribute to drive the design and the tailoring of S/F interfaces also in view of potential applications in quantum computing.

Abstract Many large unit-cell rare-earth transition metal ternary alloys of the type Ra(M1−x M’ x )b exhibit non-monotonic ferrimagnetic Curie temperatures (T C) coupled to monotonic composition-controlled magnetization. Its origin remains an important long-standing puzzle in the absence of studies probing their temperature-dependent element-specific magnetism. Here, in order to resolve this issue and identify design principles for new R-M-M’ permanent magnets, we carry out x-ray magnetic circular dichroism (XMCD) for the series Gd6(Mn1−x Fe x )23, x = 0.0 − 0.75. The results show that the net Mn-moment reduces and switches from parallel to antiparallel for x ≥ 0.2, while the Fe-moment is always antiparallel to the Gd-moment. Kouvel-Fisher analyses of XMCD data reveals distinct sublattice T C’s and 3D Heisenberg criticality. Band structure calculations show magnetic moments and density of states consistent with experiments. The magnetic phase diagram shows three regions characterized by (i) Mn-sublattice bulk-T C > Gd-sublattice T C, (ii) a reduced common-T C for all sublattices, and (iii) Fe-sublattice bulk-T C > Gd-sublattice T C. The Mn-moment switching and gradual increase of Fe-moment combine to cause non-monotonic T C’s with monotonic magnetization. The study indicates the importance of element-specific T C’s for tuning magnetic properties.

Abstract The traditional Haber-Bosch process for ammonia production is energy-intensive and relies on harsh conditions. Plasmonic materials are considered a sustainable alternative to this process. In plasmonics, the ability to localize and enhance light fields beyond the diffraction limit offers a promising avenue for harnessing visible light for photocatalysis. Moreover, the integration of plasmonic metals with various catalysts presents a promising avenue to improve efficiency and selectivity. However, cost and stability challenges hinder large-scale applications. Researchers are actively exploring new materials, optimizing catalyst design, and improving stability to overcome these hurdles. This Review delves into the intricacies of plasmonic catalysis, including material design, co-catalyst selection, and the use of nanotechnologies for precise control of metal properties in plasmonic catalysis. It emphasizes understanding energy flow at material interfaces. Ultimately, the Review aims to establish a foundation for efficient nitrogen fixation through plasmonic photocatalysis, paving the way for a more sustainable future.

Abstract Nanoparticles have become a significant area of research, offering properties that bridge the gap between bulk materials and atomic structures. Silver nanoparticles (AgNPs), specifically, have shown promise due to their plasmonic properties. Despite extensive studies, capturing the photon-to-heat conversion efficiency of individual nanoparticles has been challenging. Here, we present an approach to determine these properties using an ultra-sensitive bolometer with a power resolution of ≈26 pW. Our investigations reveal that a single AgNP can dissipate power with a magnitude between ≈101.3 fW and ≈205.3 fW, an observation that underscores the potential of these particles for efficient energy conversion. This finding enhances the understanding of AgNPs’ behavior and pushes the field of nanoparticle plasmon physics forward. Therefore, the refined use of such nanoparticles could bring advancements across a range of applications, from high-resolution imaging and advanced spectroscopy to environmental surveillance and innovative medical treatments.

Abstract Additive manufacturing opens new possibilities for designing light-weight structures using aluminium alloys. The microstructure of two Al alloys and their corrosion resistance in NaCl and natural seawater environments were investigated. The newly designed Al-Mn-Cr-Zr based alloy showed a higher corrosion resistance than reference AlSi10Mg alloy in both environments in as printed and heat-treated conditions. The corrosion initiated in the Al matrix along the precipitates in the alloys where the Volta potential difference was found the highest. The coarser microstructure and precipitate composition of the new Al-alloy led to the formation of a resistant passive film which extended the passivity region of the Al-Mn-Cr-Zr alloy compared to the AlSi10Mg alloy. The effect of heat treatment could be seen in the microstructure as more precipitates were found in between the melt pool boundaries, which affected the corrosion initiation and slightly the pitting resistance. Overall, this study shows that a newly designed Al-alloy for additive manufacturing has a suitable corrosion resistance for applications in marine environments.

Abstract The corrosion failure of amorphous carbon (a-C) coatings is commonly ascribed to the existence of growth microdefects, which serve as pathways for corrosive fluids to permeate the substrate. Atomic layer deposition (ALD) is renowned for its ability to augment the corrosion resistance of metallic materials. Graphite-like carbon (GLC) is one of the amorphous carbon materials dominated by hybridized sp2-C bonds. In this study, an ALD-deposited Al2O3 layer is specially introduced on the Cr/GLC multilayer coating to solve the aforementioned corrosion risk of a-C by taking the sealing conception for defects. Compared to the as-deposited Cr/GLC coating, the coating encapsulated with Al2O3 layer depicts the reduction of corrosion current density over two orders of magnitude under a wide pressure range of 0.1 ~ 15 MPa. Particularly, the presence of released Crn+ and Fen+ in the corrosion solution is significantly diminished, accompanying with a small quantity of Aln+ generated in sealed coating during corrosion. Microstructural analysis and electrochemical results identified that both the dense Al2O3 layer offered strong safeguard for Cr elements released from multilayers, whilst amorphous carbon network inhibited the likelihood chloride penetration induced by partially infiltrated Al2O3, which made the synergistic contributions to the enhancement of corrosion resistance for Cr/GLC coating for deep-sea applications.

Abstract Diamond-like carbon (DLC) coating is a surface coating technology with excellent hydrogen permeation resistance and wear resistance. However, it is difficult to completely prevent hydrogen permeation, and when hydrogen penetrates into the coating layer, the DLC coating is adversely affected. Therefore, we investigated the effect of hydrogen embrittlement on the adhesion strength and wear resistance of the DLC coating layer. As the results of the research, the surface roughness of the DLC coating was increased by a maximum of 3.8 times with hydrogen charging, and the delamination ratio of the DLC coating reached about 58%. In addition, the Lc3, which refers to the adhesion strength corresponding to the complete delamination of the DLC coating, was decreased by a maximum of 2.0 N due to hydrogen permeation. In addition, the wear resistance decreased due to hydrogen permeation, and the exposed width of the substrate due to wear increased by more than 4 times. It was also determined that hydrogen blistering or hydrogen-induced cracking occurred at the interface between the DLC coating and the chromium buffer layer due to hydrogen permeation, which decreased the durability of the DLC coating.

Abstract Nanoparticles including extracellular vesicles derived from mesenchymal stem cells are of increasing interest for research and clinical use in regenerative medicine. Extracellular vesicles (EVs), including also previously named exosomes, provide a promising cell-free tool for therapeutic applications, which is probably a safer approach to achieve sufficient healing. Storage of EVs may be necessary for clinical applications as well as for further experiments, as the preparation is sometimes laborious and larger quantities tend to be gained. For this purpose, nanoparticles were obtained from mesenchymal stem cells from adipose tissue (AdMSC) of horses and dogs. The EVs were then stored for 7 days under different conditions (− 20 °C, 4 °C, 37 °C) and with the addition of various additives (5 mM EDTA, 25–250 µM trehalose). Afterwards, the size and number of EVs was determined using the nano tracking analyzing method. With our investigations, we were able to show that storage of EVs for up to 7 days at 4 °C does not require the addition of supplements. For the other storage conditions, in particular freezing and storage at room temperature, the addition of EDTA was found to be suitable for preventing aggregation of the particles. Contrary to previous publications, trehalose seems not to be a suitable cryoprotectant for AdMSC-derived EVs. The data are useful for processing and storage of isolated EVs for further experiments or clinical approaches in veterinary medicine.

Abstract A nanofiber-based composite nonwoven fabric was fabricated for hemostatic wound dressing, integrating polyvinyl alcohol (PVA), kaolin, and γ-chitosan extracted from three type of insects. The γ-chitosan extracted from Protaetia brevitarsis seulensis exhibited the highest yield at 21.5%, and demonstrated the highest moisture-binding capacity at 535.6%. In the fabrication process of PVA/kaolin/γ-chitosan nonwoven fabrics, an electrospinning technique with needle-less and mobile spinneret was utilized, producing nanofibers with average diameters ranging from 172 to 277 nm. The PVA/kaolin/γ-chitosan nonwoven fabrics demonstrated enhanced biocompatibility, with cell survival rates under certain compositions reaching up to 86.9% (compared to 74.2% for PVA). Furthermore, the optimized fabric compositions reduced blood coagulation time by approximately 2.5-fold compared to PVA alone, highlighting their efficacy in hemostasis. In other words, the produced PVA/kaolin/γ-chitosan nonwoven fabrics offer potential applications as hemostatic wound dressings with excellent biocompatibility and improved hemostatic performance. Graphical abstract

Abstract Graphene quantum dots (GQDs) are a newly developed class of material, known as zero-dimensional nanomaterials, with characteristics derived from both carbon dots (CDs) and graphene. GQDs exhibit several ideal properties, including the potential to absorb incident energy, high water solubility, tunable photoluminescence, good stability, high drug-loading capacity, and notable biocompatibility, which make them powerful tools for various applications in the field of biomedicine. Additionally, GQDs can be incorporated with additional materials to develop nanocomposites with exceptional qualities and enriched functionalities. Inspired by the intriguing scientific discoveries and substantial contributions of GQDs to the field of biomedicine, we present a broad overview of recent advancements in GQDs-based nanocomposites for biomedical applications. The review first outlines the latest synthesis and classification of GQDs nanocomposite and enables their use in advanced composite materials for biomedicine. Furthermore, the systematic study of the biomedical applications for GQDs-based nanocomposites of drug delivery, biosensing, photothermal, photodynamic and combination therapies are emphasized. Finally, possibilities, challenges, and paths are highlighted to encourage additional research, which will lead to new therapeutics and global healthcare improvements.

Abstract The present research aimed at green synthesis of Ag nanoparticles (AgNPs) based colorimetric sensor using persimmon leaf extract (PLE) for selective detection of mercuric ion (Hg2+). Optimization of reaction conditions viz. pH, concentration of PLE, time was done and further AgNPs were characterized using UV, IR, FE-SEM, EDX, XRD and TEM analysis. The developed AgNPs were evaluated for the selective colorimetric detection of Hg2+ in aqueous medium and fluorescence imaging of Hg2+ ions in liver cell lines. Later, the antibacterial activity of AgNPs was performed against S. aureus and E. coli. The findings of the study revealed that PLE mediated AgNPs exhibited notable limit of detection up to 0.1 ppb, high efficiency, and stability. The antibacterial study indicated that developed AgNPs has impressive bacterial inhibiting properties against the tested bacterial strains. In conclusion, developed biogenic AgNPs has high selectivity and notable sensitivity towards Hg2+ ions and may be used as key tool water remediation. Graphical abstract

Abstract In the era of ubiquitous computing with flourished visual displays in our surroundings, the application of haptic feedback technology still remains in its infancy. Bridging the gap between haptic technology and the real world to enable ambient haptic feedback on various physical surfaces is a grand challenge in the field of human-computer interaction. This paper presents the concept of an active electronic skin, characterized by three features: richness (multi-modal haptic stimuli), interactivity (bi-directional sensing and actuation capabilities), and invisibility (transparent, ultra-thin, flexible, and stretchable). By deploying this skin on physical surfaces, dynamic and versatile multi-modal haptic display, as well as tactile sensing, can be achieved. The potential applications of this skin include two categories: skin for the physical world (such as intelligent home, intelligent car, and intelligent museum), and skin for the digital world (such as haptic screen, wearable device, and bare-hand device). Furthermore, existing skin-based haptic display technologies including texture, thermal, and vibrotactile feedback are surveyed, as well as multidimensional tactile sensing techniques. By analyzing the gaps between current technologies and the goal of ambient haptics, future research topics are proposed, encompassing fundamental theoretical research on the physiological and psychological perception mechanisms of human skin, spatial-temporal registration among multimodal haptic stimuli, integration between sensing and actuation, and spatial-temporal registration between visual and haptic display. This concept of active electronic skin is promising for advancing the field of ambient haptics, enabling seamless integration of touch into our digital and physical surroundings.

In the present study, a new configuration for a micro-feed tool rest driven by piezoelectric ceramics with a rigid–flexible phase is designed. The flexible driving part of the micro-feed tool rest is optimized using the topology optimization method, which not only improves the driving stiffness, resolution and structural stability but also increases the maximum displacement. The structural stiffness achieved in finite element simulation analysis is 16.28 N µm−1, and the first natural frequency reaches 2521 Hz. A prototype of a piezoelectrically driven micro-feed tool holder and a testing platform are constructed, and the structural stiffness of the prototype is determined to be 15.53 N µm−1 via analysis and testing, resulting in an error of 4.8 % compared with the finite element simulation results. The first-order natural frequency is 2636 Hz given a resolution of 12 nm and a maximum output displacement of 12.983 µm. Compared with the double-parallel flexible hinge, the maximum stroke of the micro-feed tool holder increases by about 5.4 µm and the resolution is improved by about 50 %. The new micro-feed tool holder developed in this paper features a cross-plate-type flexible mobile guiding mechanism. Combining stiffness, maximum travel and displacement resolution, it is applicable to precision and ultra-precision machining.

We employed a novel technique combining wire and powder co-delivery to fabricate a functionally gradient material (FGM) structure consisting of Al-based composites reinforced with alternating TiC and B4C particles. The TiC content increases from the bottom up and then decreases, while the B4C content gradually increases, resulting in a continuous gradient structure. Correspondingly, the grain size of the Al matrix also changes with the variation of ceramic particles, forming a dual-gradient change trend. This FGM structure exhibits a multi-performance balance of strength, ductility, anti-wear and damping properties, making it a promising candidate for the cost-effective application in multi-performance heterostructured components.

Carbon nanofibers (CNFs) and graphene nanosheets (GNs) are introduced to obtain nano-sized TiC particles in a novel additive manufactured Ni-Co-based superalloy. The double strengthening effects of reaction-induced TiC and remaining CNFs/GNs are conceptualized in the present paper. The CNFs and GNs act as heterogeneous nucleation sites for the formation of uniformly distributed TiC nanoparticles, which inhibits the crack and homogenize the microstructure. Interestingly, the existence of remaining GNs/CNFs is revealed via 3D atom-by-atom tomographic reconstruction technology for the first time. This unique combination of nanoparticles and residual CNFs/GNs nanofillers has great potential to develop superalloys with excellent properties.

Caries is one of the most prevalent human diseases, resulting from demineralization of tooth hard tissue caused by acids produced from bacteria, and can progress to pulpal inflammation. Filling restoration with dental resin composites (DRCs) is currently the most common treatment for caries. However, existing DRCs suffer from low fracture strength and lack comprehensive anti-caries bioactivity including remineralization, pulp protection, and anti-cariogenic bacteria effects. In this study, inspired by plant roots’ ability to stabilize and improve soil, fluorinated urchin-like hydroxyapatite (FUHA) with a three-dimensional whisker structure and bioactive components of calcium, phosphorus, and fluorine was designed and synthesized by a dynamic self-assembly method. Furthermore, versatile FUHA particles with different loading fractions were used as functional fillers to fabricate methacrylate-based DRCs, where the urchin-like hydroxyapatite (UHA) filled DRCs and commercial DRCs (Z350XT and BEAUTIFIL II) served as the control groups. The results demonstrated that FUHA with 50 wt% loading in resin matrix endowed DRC (F5) with excellent physicochemical properties, dentin remineralization property, cell viability, promotion of dental pulp stem cells mineralization, and antibacterial properties. Meanwhile, F5 also presented good clinical handling and aesthetic characteristics. Therefore, structure/functional-integrated FUHA filled DRCs have potential as a promising strategy for tooth restoration and anti-caries bioactivity.

Utilizing excess vacancy to form effective solute clusters has been considered as a potential strategy to strengthen Al alloys. Herein, we designed a cryogenic submerged friction stir processing, by the one-step process in a short time, to realize the coexistence of grain refinement, high-density clusters, and nanoprecipitates, thus enhancing strength and ductility simultaneously. The atomic information showed the unique formation of high-density clusters (1 ∼ 2 nm), which was related to the strain-induced migration of solute atoms. This study may provide a new strategy for alloys with low alloying content that can be enhanced by forming solute clusters.

We used powder hot extrusion followed by annealing to fabricate a dual-phase AlCoCrFeNi2.1 eutectic high-entropy alloy consisting of both non-recrystallized and recrystallized grains with dense nano-sized precipitates arranged in heterogeneous structures. The resulting alloy exhibits superior tensile properties with a yield strength of ∼1.2 GPa, an ultimate tensile strength of ∼1.5 GPa, and a uniform elongation of ∼18%. Such multiscale microstructure results in exceptional strain hardening of the AlCoCrFeNi2.1 alloy by activating remarkable hetero-deformation induced (HDI) stresses. Our study provides an effective approach to fabricating high-performance structural materials via dual-phase heterogeneous microstructure design.

Additive manufacturing has ushered in a new paradigm of bottom-up materials-by-design of spatially non-uniform materials. Functionally graded materials have locally tailored compositions to provide optimized global properties and performance. In this letter, we propose an opportunity for the application of graded magnetic materials as lens elements for charged particle optics. A Hiperco50/Hymu80 (FeCo-2 V/Fe-80Ni-5Mo) graded magnetic alloy was successfully additively manufactured via Laser Directed Energy Deposition with spatially varying magnetic properties. The compositional gradient is then applied using computational simulations to demonstrate how a tailored material can enhance the magnetic performance of a critical, image-forming component of a transmission electron microscope.

A novel (8.5Al3BC + 14.5Al2O3)/Al composite was fabricated with exceptional elevated-temperature properties and stiffness. The composite boasts an average Young’s modulus of 99 GPa, with ultimate tensile strength and elongation of the composite at 350°C averaging 188 MPa and 4.4%, respectively. The synergistic strengthening effect of Al3BC and γ-Al2O3 is responsible for the high-temperature properties, while they both contribute to the improvement of stiffness as they have a high initial Young’s modulus. This innovative composite design holds promising potential for advancements in material engineering and performance optimization.

Extended X-ray absorption fine structure (EXAFS) conducted on an equiatomic MoNbTaW bcc medium-entropy alloy that was annealed at 2273 K reveals unexpectedly small 1st and 2nd shell element-specific lattice distortions. An experimental size-mismatch parameter, [Formula: see text], is determined to be ca. 50% lower than the corresponding calculated value. Around W, short-range order (SRO) preferring 4d elements in the 1st and 2nd shells persists. A Nb-W ordering is found, which is reminiscent of ordering emerging at lower temperatures in the B2(Mo,W;Ta,Nb)- and B32(Nb,W)-phases. With high-temperature ordering preferences in fcc also foreshadowing low-temperature phase, these findings suggest a general feature of high-temperature SRO.

Polymers, with various advantages including lightweight, low cost, flexibility and ease of processing, are popular choices for thermal management in flexible electronics, photovoltaics, fuel cells, etc. In this perspective, we review the recent progress of developing uniaxial thermally conductive polymers and three-dimensional polymers with high thermal conductivity, discuss new opportunities in applying machine learning methods to search for thermally conductive polymers, and finally point out current key challenges and future directions in simulations and experimental measurements. The useful insights in this perspective can guide the rational design of thermally conductive polymers for advanced thermal management.

This work presents the use of natural rubber (NR) grafted with poly(vinyl propionate) (NR-g-PVP) as an alternative compatibilizer in silica-filled NR compounds. The effects of NR-g-PVP with 10, 20 and 30% grafting on the properties of NR compounds were studied and compared with a commercial coupling agent (bis[3-(triethoxysilyl)propyl] tetrasulfide, TESPT). NR-g-PVP was compatible with silica and NR. The NR-g-PVP reduced filler-filler interactions and increased fillerrubber interactions. The crosslink density decreased with the percentage of grafting due to the steric hindrance. The compatibilization affected the physical and mechanical properties. The interactions of NR-g-PVP with silica via hydrogen bonding and subsequent vulcanization prevented undesirable filler-filler interactions and reduced the absorption of accelerators or basic materials. It caused a good dispersion of silica in the NR matrix and improved physical and mechanical properties. A 10% grafting (G10) was suitable for the compatibilizer in a silica-filled NR compound, showing the largest improvements in tensile properties, tear strength, and hardness. However, TESPT provided better properties than G10.

Zinc complexes have a considerable impact on human health and the environment, especially on aquatic wildlife. One of the primary sources of zinc release to the environment is worn rubber particles from tires. The environmental footprint of zinc oxide (ZnO) during production, use, and landfilling has prompted researchers to reduce its use in rubber formulations due to ecological and economic concerns. In this study, composite ZnO materials where ZnO particles are coated on precipitated calcium carbonate (CaCO3) are used in styrene butadiene rubber/butadiene rubber (SBR/BR) compounds, and their performance is compared with white seal ZnO and active ZnO. Trial compounds are prepared on a laboratory scale using composite ZnO materials with ZnO:CaCO3 ratios of 40:60, 60:40, and 90:10, and control compounds with white seal and active ZnO. All compounds are tested to evaluate their curing and physico-mechanical properties. It is observed that the surface area of ZnO plays an essential role in crosslink density and, hence, compound performance. Trial materials have no negative effect on the curing and mechanical properties of the compounds. Thus, it is concluded that composite ZnO materials can be used as alternatives to both white seal ZnO and active ZnO. They have environmental and economic advantages due to their lower ZnO content. The compound recipe has the potential to be used for tire tread compounds.

Novel nonterminal liquid crystalline epoxy resin has been synthesized, and its structure and nature have been determined via nuclear magnetic resonance (NMR) and polarized optical microscopy (POM). Then, it was cured with the use of 4,4′-diaminodiphenylmethane (4,4′-DDM). The curing process has been investigated via differential scanning calorimetry (DSC) and infrared spectroscopy (FTIR) methods. Polymerization has been conducted with (1.2 T) and without the presence of a strong magnetic field. The properties of the obtained polymers have been described using DSC, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), dielectric spectroscopy (DS) and X-ray scattering studies (WAXS/SAXS). It has been proved that the magnetic field induces molecular ordering and increases the glass transition temperature (Tg) by over 20 °C. The obtained ordered polymers are thermally stable up to over 300 °C, undergo vitrification at slightly elevated temperature (37.5 °C), and their electrical conductivity rises significantly at the transition to an elastic state, which, among other possibilities, makes them a proper candidate for a smart, lightweight polymers with tuneable properties by a subtle temperature rise and possibility of tailoring its structure by a magnetic field.

Smart materials represent an emerging and highly exploited category, particularly in the creation of textiles that can sense and respond to various external stimuli, such as temperature or humidity. This study introduces for the first time the hygroscopic elongation and drying shrinkage properties of stimulus-responsive single-component polyamide (PA) fibers copolymerized with polyetherdiamine and diethylenetriamine (DETA). PA copolymers containing 5–15% polyetherdiamine were comprehensively characterized, including nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR), relative viscosity, and differential scanning calorimetry (DSC) analyses. Subsequently, these PA copolymers were successfully melt-spun into fibers and knitted into double-layered fabrics. PA fibers containing 15% polyetherdiamine showed significant results, with a moisture-absorbing elongation of 15.6% and a drying shrinkage of 94.9%. The Qmax and moisture regain of the PA fabric are 0.206 W·cm–2 and 4.4%, respectively. These moisture-driven, fiber-based smart textiles exhibit changes in breathability and shape retention at different humidity levels, thereby maintaining a more comfortable microclimate. Such textiles have great potential for widespread use in clothing, helping to improve comfort and adaptability.

Controlled development of novel materials fosters innovation in the electrical sector. The hybrid materials based on magnetic nanocellulose are intriguing since they have many uses in electronics, catalysis, medicine, and ecology. The study investigated the structure and morphology of hybrid nanomaterials made from nanocellulose and cobalt ferrite. The nanocellulose was prepared by TEMPO-oxidation and the cobalt ferrite was prepared by sol-gel auto-combustion method. Using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) techniques, it was determined how nanocellulose loading affected the crystal structure of the synthesized composite. To ascertain the variation in the component concentrations, scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDAX) are used. Composite with a higher concentration of nanocellulose fibers (NCF) show lesser particle size, and this may account for the smaller size of nanocellulose fibers, and attachment of nanocellulose nanofibers over the surface of porous cobalt ferrite (CF) found in SEM images.

The structure and property relationships of graft copolymers from natural rubber (NR) and polymethyl methacrylate (PMMA) crosslinked with a phenolic resin were investigated. The NR grafted with PMMA (NR-g-PMMA) having different grafting levels was initially prepared by emulsion polymerization before compounding and vulcanization. Then, proton nuclear magnetic resonance and transmission electron microscopy were used to verify the resultant NR-g-PMMAs. The graft copolymers crosslinked with phenolic resin exhibited improvements in various properties. Tensile modulus and tensile strength increased at least 18 and 95%, respectively, over the un-grafted counterpart and further improved with grafting percentage, while the elongation at break decreased accordingly. Storage modulus in rubbery plateau increased while tanδ peak height decreased with PMMA content. Moreover, the thermal stability of the graft copolymers was also improved over that of the plain NR at least 23 °C, depending on MMA contents. These improvements are tentatively attributed to the strong adhesion between NR and PMMA phases, based on interactions between the functional groups of PMMA and hydrogen bonding between phenolic resin crosslinker and PMMA. The results clearly suggest that the phenolic resin could be an effective crosslinker for NR-g-PMMA.

Thermoplastic vulcanizates (TPVs) were prepared by blending natural rubber (NR) and polypropylene (PP) using dynamic sulfur curing systems with varying accelerator/sulfur ratios: 0.5/2.5, 1.5/1.5, and 2.5/0.5 phr, categorized as conventional (CV), semi-efficient (semi-EV), and efficient (EV). The onset of dynamic vulcanization closely corresponded with scorch time in statically cured NR compounds. Mixing torque decreased over time, reflecting reversion patterns in static curing. The CV system exhibited the highest reversion tendency due to polysulfide linkage breakdown, forming stronger but shorter crosslinks. Dynamic vulcanization induced higher reversion than static curing, influenced by shear and extensional forces. Curing systems caused crosslinking rates, reversion, and crosslink density and distribution variations. Unlike statically cured NR, PP-extracted TPVs exhibited an inverse trend in total crosslink densities and distributions; TPVs primarily comprised shorter crosslinks with opposed total crosslink densities ranked EV > semi-EV > CV. This trend is strongly correlated with superior mechanical strength, toughness, storage modulus, viscosity, and rubber elasticity in the EV-cured TPV. EV system also had the smallest vulcanized NR domains in the PP matrix.

Rheumatoid arthritis (RA) is a severe autoimmune disease with symptoms including synovial inflammation, cartilage erosion, and bone loss in RA lesions, which eventually lead to joint deformity and function loss. Most current treatments fail to achieve satisfying therapeutic outcomes with some adverse effects. Extracellular vesicles derived from apoptotic cells (apoEVs) have emerged as important mediators in intercellular communication regulating diverse physiological and pathological processes. In this study, we investigated the therapeutic efficacy of macrophage-derived and osteoclast-derived apoEVs (Mφ-apoEVs and OC-apoEVs) on RA. The in vitro results showed that both Mφ-apoEVs and OC-apoEVs induced macrophage repolarization toward the anti-inflammatory M2 phenotype, promoted chondrocyte functions and chondrogenesis, and inhibited osteoclast formation and maturation. In addition, OC-apoEVs promoted osteogenic differentiation. The in vivo study on the CIA mouse model further demonstrated that apoEVs could couple various functions and exert synergistic effects on the joint with RA, as evidenced by the regression of synovial inflammation, the reversal of cartilage damage and bone erosion, and the preservation of joint structure. These findings demonstrated that Mφ-apoEVs and OC-apoEVs contributed to restoring the homeostasis of the overall microenvironment in the RA joint and highlighted their potential application as a promising alternative to treat RA.

The biophysical factors of biomaterials such as their stiffness regulate stem cell differentiation. Energy metabolism has been revealed an essential role in stem cell lineage commitment. However, whether and how extracellular matrix (ECM) stiffness regulates energy metabolism to determine stem cell differentiation is less known. Here, the study reveals that stiff ECM promotes glycolysis, oxidative phosphorylation, and enhances antioxidant defense system during osteogenic differentiation in MSCs. Stiff ECM increases mitochondrial fusion by enhancing mitofusin 1 and 2 expression and inhibiting the dynamin-related protein 1 activity, which contributes to osteogenesis. Yes-associated protein (YAP) impacts glycolysis, glutamine metabolism, mitochondrial dynamics, and mitochondrial biosynthesis to regulate stiffness-mediated osteogenic differentiation. Furthermore, glycolysis in turn regulates YAP activity through the cytoskeletal tension-mediated deformation of nuclei. Overall, our findings suggest that YAP is an important mechanotransducer to integrate ECM mechanical cues and energy metabolic signaling to affect the fate of MSCs. This offers valuable guidance to improve the scaffold design for bone tissue engineering constructs.

Rehabilitation and regenerative medicine are two promising approaches for spinal cord injury (SCI) recovery, but their combination has been limited. Conductive biomaterials could bridge regenerative scaffolds with electrical stimulation by inducing axon regeneration and supporting physiological electrical signal transmission. Here, we developed aligned conductive hydrogel fibers by incorporating carbon nanotubes (CNTs) into methacrylate acylated gelatin (GelMA) hydrogel via rotating liquid bath electrospinning. The electrospun CNT/GelMA hydrogel fibers mimicked the micro-scale aligned structure, conductivity, and soft mechanical properties of neural axons. For in vitro studies, CNT/GelMA hydrogel fibers supported PC12 cell proliferation and aligned adhesion, which was enhanced by electrical stimulation (ES). Similarly, the combination of aligned CNT/GelMA hydrogel fibers and ES promoted neuronal differentiation and axon-like neurite sprouting in neural stem cells (NSCs). Furthermore, CNT/GelMA hydrogel fibers were transplanted into a T9 transection rat spinal cord injury model for in vivo studies. The results showed that the incorporating CNTs could remain at the injury site with the GelMA fibers biodegraded and improve the conductivity of regenerative tissue. The aligned structure of the hydrogel could induce the neural fibers regeneration, and the ES enhanced the remyelination and axonal regeneration. Behavioral assessments and electrophysiological results suggest that the combination of aligned CNT/GelMA hydrogel fibers and ES could significantly restore motor function in rats. This study demonstrates that conductive aligned CNT/GelMA hydrogel fibers can not only induce neural regeneration as a scaffold but also support ESto promote spinal cord injury recovery. The conductive hydrogel fibers enable merging regenerative medicine and rehabilitation, showing great potential for satisfactory locomotor recovery after SCI.

During skin aging, the degeneration of epidermal stem cells (EpiSCs) leads to diminished wound healing capabilities and epidermal disintegration. This study tackles this issue through a comprehensive analysis combining transcriptomics and untargeted metabolomics, revealing age-dependent alterations in the Gpx gene family and arachidonic acid (AA) metabolic networks, resulting in enhanced ferroptosis. Selenomethionine (Se-Met) could enhance GPX4 expression, thereby assisting EpiSCs in countering AA-induced mitochondrial damage and ferroptosis. Additionally, Se-Met demonstrates antioxidative characteristics and extensive ultraviolet absorption. For the sustained and controllable release of Se-Met, it was covalently grafted to UV-responsive GelMA hydrogels via AC-PEG-NHS tethers. The Se-Met@GelMA hydrogel effectively accelerated wound healing in a chronological aging mice model, by inhibiting lipid peroxidation and ferroptosis with augmented GPX4 expression. Moreover, in a photoaging model, this hydrogel significantly mitigated inflammatory responses, extracellular matrix remodeling, and ferroptosis in UV-exposed mice. These characteristics render Se-Met@GelMA hydrogel valuable in practical clinical applications.

Polymyxins are the last line of defense against multidrug-resistant (MDR) Gram-negative bacterial infections. However, this last resort has been threatened by the emergence of superbugs carrying the mobile colistin resistance gene-1 (mcr-1). Given the high concentration of matrix metalloproteinase 3 (MMP-3) in bacterial pneumonia, limited plasma accumulation of colistin (CST) in the lung, and potential toxicity of ionic silver (Ag+), we designed a feasible clinical transformation platform, an MMP-3 high-performance lung-targeted bio-responsive delivery system, which we named “CST&Ag@CNMS”. This system exhibited excellent lung-targeting ability (>80% in lungs), MMP-3 bio-responsive release property (95% release on demand), and synergistic bactericidal activity in vitro (2–4-fold minimum inhibitory concentration reduction). In the mcr-1+ CST-resistant murine pneumonia model, treatment with CST&Ag@CNMS improved survival rates (70% vs. 20%), reduced bacteria burden (2–3 log colony-forming unit [CFU]/g tissue), and considerably mitigated inflammatory response. In this study, CST&Ag@CNMS performed better than the combination of free CST and AgNO3. We also demonstrated the superior biosafety and biodegradability of CST&Ag@CNMS both in vitro and in vivo. These findings indicate the clinical translational potential of CST&Ag@CNMS for the treatment of lung infections caused by CST-resistant bacteria carrying mcr-1.

Obesity triggers inflammatory responses in the microenvironment of white adipose tissue, resulting in chronic systemic inflammation and the subsequent development of non-communicable diseases, including type 2 diabetes, coronary heart disease, and breast cancer. Current therapy approaches for obesity-induced non-communicable diseases persist in prioritizing symptom remission while frequently overlooking the criticality of targeting and alleviating inflammation at its source. Accordingly, this review highlights the importance of the microenvironment of obese white adipose tissue and the promising potential of employing immunotherapy to target it as an effective therapeutic approach for non-communicable diseases induced by obesity. Additionally, this review discusses the challenges and offers perspective about the immunotherapy targeting the microenvironment of obese white adipose tissue.

Peripheral nerve injury (PNI) seriously affects the health and life of patients, and is an urgent clinical problem that needs to be resolved. Nerve implants prepared from various biomaterials have played a positive role in PNI, but the effect should be further improved and thus new biomaterials is urgently needed. Ovalbumin (OVA) contains a variety of bioactive components, low immunogenicity, tolerance, antimicrobial activity, non-toxicity and biodegradability, and has the ability to promote wound healing, cell growth and antimicrobial properties. However, there are few studies on the application of OVA in neural tissue engineering. In this study, OVA implants with different spatial structures (membrane, fiber, and lyophilized scaffolds) were constructed by casting, electrospinning, and freeze-drying methods, respectively. The results showed that the OVA implants had excellent physicochemical properties and were biocompatible without significant toxicity, and can promote vascularization, show good histocompatibility, without excessive inflammatory response and immunogenicity. The in vitro results showed that OVA implants could promote the proliferation and migration of Schwann cells, while the in vivo results confirmed that OVA implants (the E5/70% and 20 kV 20 μL/min groups) could effectively regulate the growth of blood vessels, reduce the inflammatory response and promote the repair of subcutaneous nerve injury. Further on, the high-throughput sequencing results showed that the OVA implants up-regulated differential expression of genes related to biological processes such as tumor necrosis factor-α (TNF-α), phosphatidylinositide 3-kinases/protein kinase B (PI3K-Akt) signaling pathway, axon guidance, cellular adhesion junctions, and nerve regeneration in Schwann cells. The present study is expected to provide new design concepts and theoretical accumulation for the development of a new generation of nerve regeneration implantable biomaterials.

The bidirectional relationship between osteochondral defects (OCD) and osteoarthritis (OA), with each condition exacerbating the other, makes OCD regeneration in the presence of OA challenging. Type II collagen (Col2) is important in OCD regeneration and the management of OA, but its potential applications in cartilage tissue engineering are significantly limited. This study investigated the regeneration capacity of Col2 scaffolds in critical-sized OCDs under surgically induced OA conditions and explored the underlying mechanisms that promoted OCD regeneration. Furthermore, the repair potential of Col2 scaffolds was validated in over critical-sized OCD models. After 90 days or 150 days since scaffold implantation, complete healing was observed histologically in critical-sized OCD, evidenced by the excellent integration with surrounding native tissues. The newly formed tissue biochemically resembled adjacent natural tissue and exhibited comparable biomechanical properties. The regenerated OA tissue demonstrated lower expression of genes associated with cartilage degradation than native OA tissue but comparable expression of genes related to osteochondral anabolism compared with normal tissue. Additionally, transcriptome and proteome analysis revealed the hindrance of TGF-β-Smad1/5/8 in regenerated OA tissue. In conclusion, the engrafting of Col2 scaffolds led to the successful regeneration of critical-sized OCDs under surgically induced OA conditions by inhibiting the TGF-β-Smad1/5/8 signaling pathway.

Osteoarthritis (OA), a common degenerative disease, is characterized by high disability and imposes substantial economic impacts on individuals and society. Current clinical treatments remain inadequate for effectively managing OA. Organoids, miniature 3D tissue structures from directed differentiation of stem or progenitor cells, mimic native organ structures and functions. They are useful for drug testing and serve as active grafts for organ repair. However, organoid construction requires extracellular matrix-like 3D scaffolds for cellular growth. Hydrogel microspheres, with tunable physical and chemical properties, show promise in cartilage tissue engineering by replicating the natural microenvironment. Building on prior work on SF-DNA dual-network hydrogels for cartilage regeneration, we developed a novel RGD-SF-DNA hydrogel microsphere (RSD-MS) via a microfluidic system by integrating photopolymerization with self-assembly techniques and then modified with Pep-RGDfKA. The RSD-MSs exhibited uniform size, porous surface, and optimal swelling and degradation properties. In vitro studies demonstrated that RSD-MSs enhanced bone marrow mesenchymal stem cells (BMSCs) proliferation, adhesion, and chondrogenic differentiation. Transcriptomic analysis showed RSD-MSs induced chondrogenesis mainly through integrin-mediated adhesion pathways and glycosaminoglycan biosynthesis. Moreover, in vivo studies showed that seeding BMSCs onto RSD-MSs to create cartilage organoid precursors (COPs) significantly enhanced cartilage regeneration. In conclusion, RSD-MS was an ideal candidate for the construction and long-term cultivation of cartilage organoids, offering an innovative strategy and material choice for cartilage regeneration and tissue engineering.

Atherosclerosis is featured as chronic low-grade inflammation in the arteries, which leads to the formation of plaques rich in lipids. M2 macrophage-derived extracellular vesicles (M2EV) have significant potential for anti-atherosclerotic therapy. However, their therapeutic effectiveness has been hindered by their limited targeting capability in vivo. The objective of this study was to create the P-M2EV (platelet membrane-modified M2EV) using the membrane fusion technique in order to imitate the interaction between platelets and macrophages. P-M2EV exhibited excellent physicochemical properties, and microRNA (miRNA)-sequencing revealed that the extrusion process had no detrimental effects on miRNAs carried by the nanocarriers. Remarkably, miR-99a-5p was identified as the miRNA with the highest expression level, which targeted the mRNA of Homeobox A1 (HOXA1) and effectively suppressed the formation of foam cells in vitro. In an atherosclerotic low-density lipoprotein receptor-deficient (Ldlr−/−) mouse model, the intravenous injection of P-M2EV showed enhanced targeting and greater infiltration into atherosclerotic plaques compared to regular extracellular vesicles. Crucially, P-M2EV successfully suppressed the progression of atherosclerosis without causing systemic toxicity. The findings demonstrated a biomimetic platelet-mimic system that holds great promise for the treatment of atherosclerosis in clinical settings.