Showing papers by "Weiwei Gao published in 2022"

A Review on Graphene‐Based Electromagnetic Functional Materials: Electromagnetic Wave Shielding and Absorption

Abstract: Electromagnetic (EM) functional materials play an increasingly important role in solving EM wave pollution in both modern military and civil fields. Graphene‐based materials are the most promising candidates in the applications of EM wave shielding and absorption owing to their remarkable structures and enhanced EM properties. Designing graphene‐based materials with elaborately controlled microstructures and optimized EM properties can effectively improve EM energy attenuation and conversion. Herein, the study begins with the EM attenuation mechanism, and multiscale design strategies of graphene‐based EM functional materials are outlined, including molecular‐scale, micro/nanoscale structure, macroscale structure, and integration of multiscale assembly design strategies. Applications in the EM wave shielding and absorption fields are reviewed, focusing on the latest advances in graphene‐based assemblies such as films, fabrics, and composites. Finally, the current challenges and future directions in this fast‐growing field are predicted.

Nanoparticle-modified microrobots for in vivo antibiotic delivery to treat acute bacterial pneumonia

Abstract: Bioinspired microrobots capable of actively moving in biological fluids have attracted considerable attention for biomedical applications because of their unique dynamic features that are otherwise difficult to achieve by their static counterparts. Here we use click chemistry to attach antibiotic-loaded neutrophil membrane-coated polymeric nanoparticles to natural microalgae, thus creating hybrid microrobots for the active delivery of antibiotics in the lungs in vivo. The microrobots show fast speed (>110 µm s−1) in simulated lung fluid and uniform distribution into deep lung tissues, low clearance by alveolar macrophages and superb tissue retention time (>2 days) after intratracheal administration to test animals. In a mouse model of acute Pseudomonas aeruginosa pneumonia, the microrobots effectively reduce bacterial burden and substantially lessen animal mortality, with negligible toxicity. Overall, these findings highlight the attractive functions of algae–nanoparticle hybrid microrobots for the active in vivo delivery of therapeutics to the lungs in intensive care unit settings. Biohybrid microrobots consisting of nanoparticle-modified microalgae are constructed for active drug delivery in the lungs. In an acute bacterial pneumonia model, the microrobots effectively reduce bacterial burden and lessen animal mortality.

Gastrointestinal tract drug delivery using algae motors embedded in a degradable capsule

Abstract: The use of micromotors for active drug delivery via oral administration has recently gained considerable interest. However, efficient motor-assisted delivery into the gastrointestinal (GI) tract remains challenging, owing to the short propulsion lifetime of currently used micromotor platforms. Here, we report on an efficient algae-based motor platform, which takes advantage of the fast and long-lasting swimming behavior of natural microalgae in intestinal fluid to prolong local retention within the GI tract. Fluorescent dye or cell membrane-coated nanoparticle functionalized algae motors were further embedded inside a pH-sensitive capsule to enhance delivery to the small intestines. In vitro, the algae motors displayed a constant motion behavior in simulated intestinal fluid after 12 hours of continuous operation. When orally administered in vivo into mice, the algae motors substantially improved GI distribution of the dye payload compared with traditional magnesium-based micromotors, which are limited by short propulsion lifetimes, and they also enhanced retention of a model chemotherapeutic payload in the GI tract compared with a passive nanoparticle formulation. Overall, combining the efficient motion and extended lifetime of natural algae-based motors with the protective capabilities of oral capsules results in a promising micromotor platform capable of achieving greatly improved cargo delivery in GI tissue for practical biomedical applications.

Isotropically Ultrahigh Thermal Conductive Polymer Composites by Assembling Anisotropic Boron Nitride Nanosheets into a Biaxially Oriented Network.

Abstract: The demand for thermally conductive but electrically insulating materials has increased greatly in advanced electronic packaging. To this end, polymer-based composites filled with boron nitride (BN) nanosheets have been intensively studied as thermal interface material (TIM). However, it remains a great challenge to achieve isotropically ultrahigh thermal conductivity in BN/polymer composites due to the inherent thermal property anisotropy of BN nanosheets and/or the insufficient construction of the 3D thermal conductive network. Herein, we present a high-performance BN/polymer composite with a biaxially oriented thermal conductive network by a dendritic ice template. The composite exhibits both ultrahigh in-plane (∼39.0 W m-1 K-1) and through-plane thermal conductivity (∼11.5 W m-1 K-1) at 80 vol % BN loading, largely exceeding those of reported BN/polymer composites. In addition, our composite as a TIM shows higher cooling efficiency than that of commercial TIM with up to 15 °C reduction of the chip temperature and retains good thermal stability even after 1000 heating/cooling cycles. Our strategy represents an effective approach for developing advanced thermal interface materials, which are greatly demanded for advanced electronics and emerging areas like wearable electronics.

Membrane Cholesterol Depletion Enhances Enzymatic Activity of Cell-Membrane-Coated Metal-Organic-Framework Nanoparticles.

Abstract: Metal-organic-framework nanoparticles (MOF NPs) have been increasingly used to encapsulate therapeutic enzymes for delivery. To better interface these MOF NPs with biological systems, researchers have coated them with natural cell membranes, enabling biomimicking properties suitable for innovative biomedical applications. Herein, we report that the enzymatic activity of cell-membrane-coated MOF NPs can be significantly enhanced by reducing membrane cholesterol content. We demonstrate such cholesterol-enzymatic activity correlation using ZIF-8 MOF NPs to encapsulate catalase, horseradish peroxidase, and organophosphate hydrolase, respectively. MOF NPs coated with membranes of human red blood cells or macrophages show similar outcomes, illustrating the broad applicability of this finding. The mechanistic investigation further reveals that the reduction of cholesterol levels effectively enhances membrane permeability likely responsible for the increased enzymatic activity. These results also imply a facile approach to tailoring the enzymatic activity of cell-membrane-coated MOF NPs by simply tuning the membrane cholesterol level.

An unanticipated discovery of novel naphthalimidopropanediols as potential broad-spectrum antibacterial members.

Abstract: Constructing a new antibacterial structural framework is an effective strategy to combat drug resistance. This work discovered a class of naphthalimidopropanediols (NIOLs) as a novel structural type of potential broad-spectrum antibacterial agents. Especially, NIOLs 9u, 12i, 15 against Staphylococcus aureus and NIOLs 9l, 13a against Pseudomonas aeruginosa showed excellent inhibitory activities, and they displayed high membrane selectivity from an electrostatic distinction on the membranes between bacteria and mammalian cells. These highly active NIOLs could effectually inhibit the bacterial growths, and relieve the resistance developments. Moreover, the facts of membrane depolarization, outer/inner membrane permeabilization and leakage of intracellular materials, demonstrated that these NIOLs could target and destroy the S. aureus or P. aeruginosa membranes. In particular, they could disrupt the antioxidant defense systems of S. aureus or P. aeruginosa through up-regulation of reactive oxygen species. Simultaneously, they could render the metabolic inactivation of the tested strains, and eradicate the formed biofilms and efficiently kill the strains within the biofilms. The in vitro and in vivo cytotoxicity assay indicated that these compounds possessed low toxicity. These findings of novel NIOLs as potential broad-spectrum antibacterial members provided a bright hope for conquering drug resistance.

Ice-Templated Fabrication of Porous Materials with Bioinspired Architecture and Functionality

Abstract: ConspectusBiological porous materials, such as polar bear hair, wood, bamboo, and cuttlebone, exhibit outstanding thermal and mechanical properties due to their hierarchical architectures. Specifically, polar bears can retain thermal homeostasis in the extremely cold Arctic due to outstanding thermal insulation property of their porous hairs; wood and bamboo exhibit excellent mechanical strength, highly efficient water and nutrient transport capacity, and low density due to their hierarchically aligned porous architecture; cuttlebone can resist large hydrostatic pressure in the deep-sea environment due to its mechanically efficient porous structure with lamellar septa connected by asymmetrically S-shaped walls. Obviously, the hierarchical architecture is crucial for the excellent performance of biological porous materials. Inspired by these natural design motifs, bioinspired materials with hierarchical architectures have been extensively explored for various applications where excellent mechanical, thermal, and electric properties are highly demanded. As a controllable, versatile, scalable, and environmental-friendly process, ice templating (or freeze casting) represents an effective approach to mimicking the sophisticated architecture of biological materials in synthetic counterparts, which has attracted wide attention from research groups across the world.In recent years, we have conducted comprehensive studies on the mechanism of the ice-templating approach and provided a rich toolbox based on this technique to meet various manufacturing demands. We systematically studied the material assembly process and the heat and mass transfer mechanism of the ice-templating technology from the aspects of cold surface, temperature field design, and intrinsic properties of the building blocks. First, bidirectional freezing guided by dual temperature gradients was developed to generate a long-range nacre–mimetic lamellar architecture. Next, complex hierarchical lamellar architectures were constructed through freezing on engineered cold surfaces with either wettability gradient or grooved pattern. Additionally, the “freeze-spinning” technique was developed to realize continuous and large-scale fabrication of fibers with aligned porous architecture mimicking polar bear hair. Finally, the applicability of the unidirectional ice-templating technique was broadened from soluble to insoluble polymeric materials through the freezing of emulsion droplets. These techniques have been widely used to fabricate a series of porous materials with bioinspired architectures, which hold great potential in thermal regulation, liquid transport, and mechanical functions for wide applications in various fields. Finally, a concise summary of this Account, including latest development, future challenges and opportunities in the ice-templated fabrication of bioinspired porous materials will be provided. This Account provides guidance for the design and ice-templated fabrication of bioinspired porous materials with multiscale architecture and functionality, which are crucial for various engineering applications.

Iron Phosphate Nanozyme-Hydrogel with Multienzyme-like Activity for Efficient Bacterial Sterilization.

Abstract: Pathogenic bacteria infections have posed a threat to human health worldwide. Nanomaterials with natural enzymatic activity provide an opportunity for the development of new antibacterial pathways. We successfully constructed iron phosphate nanozyme-hydrogel (FePO4-HG) with the traits of positive charge and macropores. Interestingly, FePO4-HG displayed not only peroxidase-like activity under acidic bacterial infectious microenvironment but also superoxide dismutase-catalase-like synergistic effects in neutral or weak alkaline conditions, thus protecting normal tissues from the peroxidase-like protocol with exogenous H2O2 damage. Furthermore, the positive charge and macropore structure of FePO4-HG could capture and restrict bacteria in the range of ROS destruction. Obviously, FePO4-HG exhibited excellent antibacterial ability against MRSA and AREC with the assistance of H2O2. Significantly, the FePO4-HG + H2O2 system could efficiently disrupt the bacterial biofilm formation and facilitate the glutathione oxidation process to rapid bacterial death with low cytotoxicity. Moreover, FePO4-HG was unsusceptible to bacterial resistance development in MRSA. Animal experiments showed that the FePO4-HG + H2O2 group could efficiently eliminate the MRSA infection and present excellent wound healing without inflammation and tissue adhesions. With further development and optimization, FePO4-HG has great potential as a new class of antibacterial agents to fight antibiotic-resistant pathogens.

A review on elastic graphene aerogels: Design, preparation, and applications

Abstract: Graphene aerogels with unique properties, such as ultralow density, super-elasticity, high specific surface area, and excellent thermal stability, have undergone great progress in the past decades. Especially, super-elastic graphene aerogels provide a highly attention-catching platform for developing advanced energy devices, pressure sensors, contaminates adsorbents, and electromagnetic wave shielding and absorption materials, and so forth. In this review, we begin with the introduction and discussion of various fabrication techniques and compare their advantages and disadvantages, focusing on the template-free assembly process and template-assisted assembly process. Then, we summarize the factors influencing the compressibility and elasticity of graphene aerogels, including intrinsic properties of building blocks, constituent materials, and structure design, and their wide applications. At the end, we discuss the current challenges and future prospects of this field.

Biomimetic Neutrophil Nanotoxoids Elicit Potent Immunity against Acinetobacter baumannii in Multiple Models of Infection.

Abstract: Acinetobacter baumannii is a leading cause of antibiotic-resistant nosocomial infections with high mortality rates, yet there is currently no clinically approved vaccine formulation. During the onset of A. baumannii infection, neutrophils are the primary responders and play a major role in resisting the pathogen. Here, we design a biomimetic nanotoxoid for antivirulence vaccination by using neutrophil membrane-coated nanoparticles to safely capture secreted A. baumannii factors. Vaccination with the nanotoxoid formulation rapidly mobilizes innate immune cells and promotes pathogen-specific adaptive immunity. In murine models of pneumonia, septicemia, and superficial wound infection, immunization with the nanovaccine offers significant protection, improving survival and reducing signs of acute inflammation. Lower bacterial burdens are observed in vaccinated animals regardless of the infection route. Altogether, neutrophil nanotoxoids represent an effective platform for eliciting multivalent immunity to protect against multidrug-resistant A. baumannii in a wide range of disease conditions.

Neuronal Cellular Nanosponges for Effective Detoxification of Neurotoxins.

Abstract: Neurotoxins attack and destruct the nervous system, which can cause serious health problems and security threats. Existing detoxification approaches, such as antibodies and small molecule antidotes, rely on neurotoxin's molecular structure as design cues and require toxin-specific development for each type of toxins. However, the enormous diversity of neurotoxins makes such structure-based development of antitoxin particularly challenging and inefficient. Here, we report on the development and use of neuronal membrane-coated nanosponges (denoted "Neuron-NS") as an effective approach to detoxifying neurotoxins. Specifically, Neuron-NS act as neuron decoys to lure neurotoxins, bind with and neutralize the toxins, and thus block them from attacking the host neuron cells. These nanosponges detoxify neurotoxins regardless of their molecular structures and therefore can overcome the challenge posed by toxin structural diversity. In the study, we fabricate Neuron-NS by coating the membrane of Neuro-2a cells onto polymeric cores. Meanwhile, we select tetrodotoxin (TTX) as a model neurotoxin and demonstrate the detoxification efficacy of the Neuron-NS in a cytotoxicity assay, a calcium flux assay, and a cell osmotic swelling assay in vitro. Additionally, in mouse models of TTX intoxication, the Neuron-NS significantly enhance mouse survival in therapeutic and prophylactic regimens without showing acute toxicity. Overall, the Neuron-NS contribute to the current detoxification arsenal with the potential to treat various injuries and diseases caused by neurotoxins.

Extremophile-based biohybrid micromotors for biomedical operations in harsh acidic environments

Abstract: The function of robots in extreme environments is regarded as one of the major challenges facing robotics. Here, we demonstrate that acidophilic microalgae biomotors can maintain their swimming behavior over long periods of time in the harsh acidic environment of the stomach, thus enabling them to be applied for gastrointestinal (GI) delivery applications. The biomotors can also be functionalized with a wide range of cargos, ranging from small molecules to nanoparticles, without compromising their ability to self-propel under extreme conditions. Successful GI delivery of model payloads after oral administration of the acidophilic algae motors is confirmed using a murine model. By tuning the surface properties of cargos, it is possible to modulate their precise GI localization. Overall, our findings indicate that multifunctional acidophilic algae-based biomotors offer distinct advantages compared to traditional biohybrid platforms and hold great potential for GI-related biomedical applications.

Cellular Nanodiscs Made from Bacterial Outer Membrane as a Platform for Antibacterial Vaccination.

Abstract: Vaccination has become an increasingly attractive strategy for protecting against antibiotic-resistant infections. Nanovaccines based on the outer membrane from Gram-negative bacteria are appealing due to their multiantigenic nature and inherent immunogenicity. Here, we develop cellular nanodiscs made of bacterial outer membrane (OM-NDs), as a platform for antibacterial vaccination. Using Pseudomonas aeruginosa as a model pathogen, the resulting OM-NDs can effectively interact with antigen-presenting cells, exhibiting accelerated uptake and an improved capacity for immune stimulation. With their small size, the OM-NDs are also capable of efficiently transporting to the lymph nodes after in vivo administration. As a result, the nanovaccine is effective at eliciting potent humoral and cellular immune responses against P. aeruginosa. In a murine model of pneumonia, immunization with OM-NDs confers strong protection against subsequent lung infection, resulting in improved survival, reduced bacterial loads, and alleviation of immune overactivation. Overall, this report illustrates the advantages of cellular nanodiscs, which can be readily generalized to other pathogens and may be applied toward other biomedical applications.

Label-free electrochemical detection of genetic damage induced by the interaction of a novel potential aminoanthraquinone-derived antitumor agent with DNA modified electrode

Abstract: In this work, an efficient electrochemical biosensor for the detection of DNA damage induced by the interaction of a novel antitumor agent AD-NU was investigated by CV, DPV and SWV methods. The GCE was modified with calf thymus DNA, G-quadruplexes, poly dA and poly dG, respectively. Among all the candidates, compound AD-NU was the optimum ligand because of the minimum energy when binding to DNA or TOP II by molecular docking. The electrochemical analysis revealed the redox mechanism of AD-NU on the GCE surface, which included two consecutive reversible processes of 9,10-diquinone and irreversible redox of nitroso group. The DNA damage caused by AD-NU was investigated by comparing the intensity changes of dGuo and dAdo oxidation peaks in DNA strands, and monitoring the appearance of peak for oxidative product 8-oxoGua. Further confirmation for the interaction between AD-NU and DNA was performed by UV–vis absorption and fluorescence titration, which implied the intercalation of AD-NU into DNA base pairs with a high affinity constant (Kb = 13.7 ×105 M−1). The electrophoresis also revealed the potency of AD-NU to cleave and unwind DNA strands. Finally, AD-NU was proved to have good antiproliferative activity toward tumor cells, with IC50 values of 3.0 μmol ∙ L−1 for A549 cell lines and 3.3 μmol ∙ L−1 for Hela cell lines, superior to MTZ reference.

Nanotoxoid vaccination protects against opportunistic bacterial infections arising from immunodeficiency

Abstract: The rise in nosocomial infections caused by multidrug-resistant pathogens is a major public health concern. Patients taking immunosuppressants or chemotherapeutics are naturally more susceptible to infections. Thus, strategies for protecting immunodeficient individuals from infections are of great importance. Here, we investigate the effectiveness of a biomimetic nanotoxoid vaccine in defending animals with immunodeficiency against Pseudomonas aeruginosa. The nanotoxoids use a macrophage membrane coating to sequester and safely present bacterial virulence factors that would otherwise be too toxic to administer. Vaccination with the nanoformulation results in rapid and long-lasting immunity, protecting against lethal infections despite severe immunodeficiency. The nanovaccine can be administered through multiple routes and is effective in both pneumonia and septicemia models of infection. Mechanistically, protection is mediated by neutrophils and pathogen-specific antibodies. Overall, nanotoxoid vaccination is an attractive strategy to protect vulnerable patients and could help to mitigate the threat posed by antibiotic-resistant superbugs.

Using Cell Membranes as Recognition Layers to Construct Ultrasensitive and Selective Bioelectronic Affinity Sensors.

Abstract: Conventional sandwich immunosensors rely on antibody recognition layers to selectively capture and detect target antigen analytes. However, the fabrication of these traditional affinity sensors is typically associated with lengthy and multistep surface modifications of electrodes and faces the challenge of nonspecific adsorption from complex sample matrices. Here, we report on a unique design of bioelectronic affinity sensors by using natural cell membranes as recognition layers for protein detection and prevention of biofouling. Specifically, we employ the human macrophage (MΦ) membrane together with the human red blood cell (RBC) membrane to coat electrochemical transducers through a one-step process. The natural protein receptors on the MΦ membrane are used to capture target antigens, while the RBC membrane effectively prevents nonspecific surface binding. In an attempt to detect tumor necrosis factor alpha (TNF-α) cytokine using the bioelectronic affinity sensor, it demonstrates a remarkable limit of detection of 150 pM. This new sensor design integrates natural cell membranes and electronic transduction, which offers synergistic functionalities toward a broad range of biosensing applications.

Sumanene Monolayer of Pure Carbon: A Two-Dimensional Kagome-Analogy Lattice with Desirable Band Gap, Ultrahigh Carrier Mobility, and Strong Exciton Binding Energy.

Abstract: The design and synthesis of novel two-dimensional (2D) materials that possess robust structural stability and unusual physical properties may open up enormous opportunities for device and engineering applications. Herein, a 2D sumanene lattice that can be regarded as a derivative of the conventional Kagome lattice is proposed. The tight-binding analysis demonstrates sumanene lattice contains two sets of Dirac cones and two sets of flat bands near the Fermi surface, distinctively different from the Kagome lattice. Using first-principles calculations, two possible routines for the realization of stable 2D sumanene monolayers (named α phase and β phase) are theoretically suggested, and an α-sumanene monolayer can be experimentally synthesized with chemical vapor deposition using C21 H12 as a precursor. Small binding energies on Au(111) surface (e.g., -37.86 eV Å-2 for α phase) signify the possibility of their peel-off after growing on the noble metal substrate. Importantly, the GW plus Bethe-Salpeter equation calculations demonstrate both monolayers have moderate band gaps (1.94 eV for α) and ultrahigh carrier mobilities (3.4 × 104 cm2 V-1 s-1 for α). In particular, the α-sumanene monolayer possesses a strong exciton binding energy of 0.73 eV, suggesting potential applications in optics.

Strain modulation of the exciton anisotropy and carrier lifetime in black phosphorene.

Abstract: Manipulating excitons is of great significance to explore the optical properties of 2D materials. In this work, we investigate the excitonic properties and carrier dynamics of bilayer black phosphorene by imposing in-plane biaxial strain. The results show that the strain can modulate not only the contribution of the excitons to optical absorption but also the anisotropic shape of the first exciton. This can be ascribed to the strain effect on the band realignment as well as to changes of the parity and the electron effective mass at the CBM. At the temperature of 300 K, a 3% strain reduces the non-adiabatic coupling between the VBM and CBM and then increases the carrier lifetime by a factor of 13, and the results can be used to estimate the strain effect on the excitonic lifetime. Our results demonstrate that manipulation of the biaxial strain is a promising strategy to modulate the exciton properties of black phosphorene.

Ultrasmall Iridium Nanoparticles as Efficient Peroxidase Mimics for Colorimetric Bioassays

Abstract: Cary 60 UV-vis spectrophotometer. Transmission electron microscopy (TEM) images were taken using a JEOL 1011 microscope operated at 200 kV. High-angle annular dark-field scanning TEM (HAADF-STEM) images were taken using a FEI 200 kV Titan Themis scanning transmission electron microscope. The amount of Ir nanoparticles (NPs), WO 2.72 nanorods (NRs), and the Ir/W atomic ratios of Ir/WO 2.72 nanocomposites (NCs) were obtained from inductively coupled plasma mass spectroscopy (ICP-MS) analyses using a Thermo Scientific iCAP RQ, where Ir and W were converted to ionic species through the digestion of aqua regia. X-ray Diffraction (XRD) patterns were recorded using a PANalytical Empyrean diffractometer (1.8 KW Copper X-ray Tube). X-ray photoelectron spectroscopy (XPS) was performed on a Physical Electronics 5400 ESCA spectrometer system. The fourier transform infrared (FT-IR) spectroscopy was recorded from the machine of Jasco 6600 MIR and FIR FT-IR with ATR. Microtiter plates were shaken using a Corning LSE digital microplate shaker. The absorbance of samples in microtiter plates was read

Improvement of IgA Nephropathy and Kidney Regeneration by Functionalized Hyaluronic Acid and Gelatin Hydrogel

Abstract: Immunoglobulin A (IgA) nephropathy (IgAN) is one of an important cause of progressive kidney disease and occurs when IgA settles in the kidney resulted in disrupts kidney’s ability to filter waste and excess water. Hydrogels are promising material for medical applications owing to their excellent adaptability and filling ability. Herein, we proposed a hyaluronic acid/gelatin (CHO-HA/Gel-NH2) bioactive hydrogel as a cell carrier for therapeutic kidney regeneration in IgAN. CHO-HA/Gel-NH2 hydrogel was fabricated by Schiff-base reaction without any additional crosslinking agents. The hydrogel concentrations and ratios were evaluated to enhance adequate mechanical properties and biocompatibility for further in vivo study. High serum IgA ddY mice kidneys were treated with human urine-derived renal progenitor cells encapsulated in the hydrogel to investigate the improvement of IgA nephropathy and kidney regeneration. The stiffness of the hydrogel was significantly enhanced and could be modulated by altering the concentrations and ratios of hydrogel. CHO-HA/Gel-NH2 at a ratio of 3/7 provided a promising milieu for cells viability and cells proliferation. From week four onwards, there was a significant reduction in blood urea nitrogen and serum creatinine level in Cell/Gel group, as well as well-organized glomeruli and tubules. Moreover, the expression of pro-inflammatory and pro-fibrotic molecules significantly decreased in the Gel/Cell group, whereas anti-inflammatory gene expression was elevated compared to the Cell group. Based on in vivo studies, the renal regenerative ability of the progenitor cells could be further increased by this hydrogel system.

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Abstract: The authors study the divacancy in 3C-SiC, a promising system for quantum information or sensing applications, using large-scale GW plus Bethe-Salpeter equation simulations of nearly 1000 atoms. Notably, in contrast to the widely studied diamond NV center, low-energy excitonic states of 3C-SiC divacancy show substantial characters of transitions from localized defect states to continuum states. Some defect states that contribute to the low-energy excitations significantly hybridize with conduction bands. This work quantitatively determines the quasiparticle energies of defect states and zero-phonon line energy, emphasizing the importance of frontier conduction bands on the low-energy excitons of 3C-SiC divacancy.

Improvement of IgA Nephropathy and Kidney Regeneration by Functionalized Hyaluronic Acid and Gelatin Hydrogel

Abstract: Immunoglobulin A (IgA) nephropathy (IgAN) is one of an important cause of progressive kidney disease and occurs when IgA settles in the kidney resulted in disrupts kidney’s ability to filter waste and excess water. Hydrogels are promising material for medical applications owing to their excellent adaptability and filling ability. Herein, we proposed a hyaluronic acid/gelatin (CHO-HA/Gel-NH2) bioactive hydrogel as a cell carrier for therapeutic kidney regeneration in IgAN. CHO-HA/Gel-NH2 hydrogel was fabricated by Schiff-base reaction without any additional crosslinking agents. The hydrogel concentrations and ratios were evaluated to enhance adequate mechanical properties and biocompatibility for further in vivo study. High serum IgA ddY mice kidneys were treated with human urine-derived renal progenitor cells encapsulated in the hydrogel to investigate the improvement of IgA nephropathy and kidney regeneration. The stiffness of the hydrogel was significantly enhanced and could be modulated by altering the concentrations and ratios of hydrogel. CHO-HA/Gel-NH2 at a ratio of 3/7 provided a promising milieu for cells viability and cells proliferation. From week four onwards, there was a significant reduction in blood urea nitrogen and serum creatinine level in Cell/Gel group, as well as well-organized glomeruli and tubules. Moreover, the expression of pro-inflammatory and pro-fibrotic molecules significantly decreased in the Gel/Cell group, whereas anti-inflammatory gene expression was elevated compared to the Cell group. Based on in vivo studies, the renal regenerative ability of the progenitor cells could be further increased by this hydrogel system.

Strong Dzyaloshinskii-Moriya Interaction in Monolayer CrI$_3$ on Metal Substrates

Abstract: Dzyaloshinskii-Moriya interaction (DMI) is the primary mechanism for realizing real-space chiral spin textures, which are regarded as key components for the next-generation spintronics. However, DMI arises from a perturbation term of the spin-orbit interaction and is usually weak in pristine magnetic semiconductors. To date, large DMI and the resulting skyrmions are only realized in a few materials under stringent conditions. Using first-principles calculations, we demonstrate that significant DMI occurs between nearest-neighbor Cr atoms in two-dimensional (2D) magnetic semiconductor CrI 3 on Au or Cu substrates. This exceptionally strong DMI is generated by the interfacial charge transfer and weak chemical interactions between chromium halides and metal substrates, which break the spatial inversion symmetry. These findings highlight the significance of substrate effects in 2D magnets and expand the inventory of feasible materials with strong DMI.

Aligning curved stacking bands to simultaneously strengthen and toughen lamellar materials.

Abstract: A layered architecture endows structural materials like nacre and biomimetic ceramics with enhanced mechanical performance because it introduces multiple strengthening and toughening mechanisms. Yet present studies predominantly involve enhancing the alignment in planar lamellar structures, and the effects of the stacking curvature have largely remained unexplored. Here we find that ordered curved stacking bands in lamellar structures act as a new structural mechanism to simultaneously improve strength and toughness. Aligned curved bands increase interlayer frictional resistance to show a strengthening effect and suppress the crack propagation to show an extrinsic toughening effect. In prototypical graphene oxide films, rational regulation of the intervals and orientations of curved bands bring a maximum 162% improvement in strength and 183% improvement in toughness simultaneously. Our results reveal the hidden effects of the stacking curvature on the mechanical behaviors of lamellar materials, opening an extra design dimension to fabricate stronger and tougher structural materials.