Antibacterial and self-healing sepiolite-based hybrid hydrogel for hemostasis and wound healing.

The process of wound healing necessitates a specific environment, thus prompting extensive research into the utilization of hydrogels for this purpose. While numerous hydrogel structures have been investigated, the discovery of a self-healing hydrogel possessing favorable biocompatibility, exceptional mechanical properties, and effective hemostatic and antibacterial performance remains uncommon. In this work, a polyvinyl alcohol (PVA) hybrid hydrogel was meticulously designed through a simple reaction, wherein CuxO anchored sepiolite was incorporated into the hydrogel. The results indicate that introduction of sepiolite greatly improves the toughness, self-healing and adhesion properties of the PVA hydrogels. CuxO nanoparticles endow the hydrogels with excellent antibacterial performance towards Staphylococcus aureus and Escherichia coli. The application of hybrid hydrogels for fast hemostasis and wound healing are verified in vitro and in vivo with rat experiments. This work thereby demonstrates an effective strategy for designing biodegradable hemostatic and wound healing materials.

Sustainable sepiolite-based composites for fast clotting and wound healing.

Uncontrolled bleeding and bacterial coinfection are the major causes of death after an injury. Fast hemostatic capacity, good biocompatibility, and bacterial coinfection inhibition pose great challenges to hemostatic agent development. A prospective sepiolite/Ag nanoparticles (sepiolite@AgNPs) composite has been prepared by using natural clay sepiolite as template. A tail vein hemorrhage mouse model and a rabbit hemorrhage model were used to evaluate the hemostatic properties of the composite. The sepiolite@AgNPs composite can quickly absorb fluid to subsequently stop bleeding due to the natural fibrous crystal structure of sepiolite, and inhibit bacterial growth with the antibacterial ability of AgNPs. Compared with commercially-available zeolite material, the as-prepared composite exhibits competitive hemostatic properties without exothermic reaction in the rabbit model of femoral and carotid artery injury. The rapid hemostatic effect was due to the efficient absorption of erythrocyte and activation of the coagulation cascade factors and platelets. Besides, after heat-treatment, the composites can be recycled without significant reduction of hemostatic performance. Our results also prove that sepiolite@AgNPs nanocomposites can stimulate wound healing. The sustainability, lower-cost, higher bioavailability, and stronger hemostatic efficacy of sepiolite@AgNPs composite render these nanocomposites as more favorable hemostatic agents for hemostasis and wound healing.

Nanomechanical-atomistic insights on interface interactions in asphalt mixtures with various chloride ion erosion statuses.

Coastal asphalt pavements are highly susceptible to sea salt erosion, which leads to a significant decrease in road performance and durability. However, the interface micro-adhesion mechanism of the asphalt-aggregate composites under chloride ion erosion is still not fully understood. Herein, using the silica microsphere Atomic Force Microscopy (AFM) modified tip and asphalt sample with chloride ions as a surface, we report the effect mechanism of chloride ion erosion on the interface adhesion behavior of asphalt-silica composites by AFM from the atomistic scale. The chloride ion erosion mechanism was further supported by molecular dynamics (MD) simulations. Due to the erosion effect of chloride ions, the structure evolution of the asphalt film surface will occur, and the weak adhesion gradient zone will be formed on the surface of the asphalt film. The concentration effect of chloride ions accelerates the formation of adhesion gradient zones, which are unstable and evolve over erosion time. Due to the presence of these adhesion gradient zones, water molecules will more easily penetrate the asphalt membrane and enter the asphalt-silica interface through adsorption and diffusion, thereby weakening the interface adhesion ability between the asphalt and the aggregate. Furthermore, the distribution and diffusion of asphalt fractions on the aggregate surface also affect the adhesion behavior evolution of asphalt-silica composites induced by chloride ion erosion. The evolution in the spatial distribution of fractions may be related to the formation of interfacial adhesion gradient zones. This study outcome has important theoretical significance for promoting the sustainability of asphalt pavements and for guiding pavement deicing.

Sepiolite and ZIF-67 co-modified PAN/PVdF-HFP nanofiber separators for advanced Li-ion batteries.

Electrospun PAN/PVdF-HFP membranes have the potential to be used as separators for Li-ion batteries owing to their good mechanical properties and high chemical stability. However, the application of PAN/PVdF-HFP separators has been hampered by their poor electrochemical performances. In this study, semi-aligned PAN/PVdF-HFP nanofiber separators have been fabricated by an electrospinning technology. Sepiolite and ZIF-67 co-modification was employed to enhance the physical properties of the PAN/PVdF-HFP separators. The test cells with the as-prepared composite separator showed better electrochemical performance than the commercial and raw PAN/PVdF-HFP separators.

Structural evolution of Si-based anode materials during the lithiation reaction.

Si-based materials have been intensively investigated as anode materials for Li-ion batteries. However, the structural evolution of the materials during the lithiation reaction is still unrevealed. In this paper, the structural parameters and mechanical properties of Si, SiOx(0 < x < 2) and SiO2during the lithiation reaction are studied by first-principle calculation based on density functional theory. The relationship between the Li number and expansion coefficient, elastic constant, modulus, and Poisson's ratio is systematically calculated.

Revealing compatibility mechanism of nanosilica in asphalt through molecular dynamics simulation.

The compatibility between asphalt and nanosilica (nano-SiO2) is critical to determine the performance of nano-SiO2-modified asphalt. However, a comprehensive understanding of the compatibility behavior and mechanism of asphalt components and nano-SiO2 in the modified asphalt is still limited. In this study, the compatibility was revealed through molecular dynamics (MD) simulation. Virgin asphalt, nano-SiO2-modified asphalt, and oxidation aged asphalt models produced with the COMPASS force field; meanwhile, the proposed models were validated by comparisons with reference data. The compatibility of asphalt and nano-SiO2 was analyzed by solubility and the Flory-Huggins parameters and interaction energy. Results show that the solubility parameters decreased with the increase of system temperature while increased with the asphalt's oxidation level increase. Meanwhile, the compatibility of the asphaltene, resin, and aromatic components in asphalt is better than the compatibility with saturates, which may be due to saturates being volatile; however, the compatibility of the nano-SiO2 and saturates is much better than those with asphaltene, resin, and aromatic components. The incorporation of nano-SiO2 alleviates the volatilization of saturates. The present results provide insights into the understanding of the compatibility behavior and mechanism of nano-SiO2 and asphalt components.

Preparation of ultrathin carbon-coated CdS nanobelts for advanced Li and Na storage.

In this paper, we report a simple hydrothermal method for preparation of ultrathin carbon-coated CdS (CdS@C) nanobelts. The CdS@C nanobelts show superior electrochemical properties as an anode material for Li-ion batteries. The optimized CdS@C composites deliver a reversible capacity around 910 mAhg-1 and 48 mAhg-1 at 0.1 Ag-1 and 30.0 Ag-1, respectively. Moreover, the optimized nanobelts are also potential materials for Na storage. A stable capacity around 240 mAhg-1 is obtained at 0.1 Ag-1, even after 100 cycles.

Enhanced ion diffusion induced by structural transition of Li-modified borophosphene.

Density functional theory (DFT) calculations have been carried out to investigate the performance of borophosphene in lithium-ion batteries. Our study has revealed the following: (1) the Dirac cone in the electronic structure demonstrates the metallic nature of borophosphene, implying the enhanced electronic conductivity of the anode electrodes; (2) borophosphene shows high adsorption of Li ions with binding energies in the range of -0.6 to -1.1 eV; (3) the theoretical storage capacity is significantly high, up to 1282.7 mA h g-1, and more interestingly, a structural transition is observed in the host borophosphene at a high density of Li ions; (4) at low concentrations, graphene-like borophosphene shows isotropic diffusion of Li atoms with a barrier around 0.5 eV, while at high density, the phosphorene-like borophosphene exhibits a reduced barrier in the range of 0.12-0.14 eV along the zigzag direction, suggesting strong promotion of Li-ion transportation; (5) meanwhile, owing to the structural transition, phosphorene-like borophosphene exhibits highly anisotropic migration of Li ions along the zigzag and armchair directions. These new findings present the great advantages of borophosphene as an anode material in lithium-ion batteries.

Anisotropic semi-aligned PAN@PVdF-HFP separator for Li-ion batteries.

Compared with the common electrospun nanofibers, the alignment of the nanofibers exhibits interesting anisotropic mechanical properties and structural stability. In this paper, semi-aligned PAN@PVdF-HFP nanofiber separators were prepared by a modified electrospinning method. The composite separators exhibit anisotropic mechanical properties and enhanced electrochemical performance compared with electrospun PAN films. The PAN@PVdF-HFP nanofiber separator can deliver an ionic conductivity of 1.2 mSccm-1 with electrochemical stability up to 5.0 V. The LiFePO4/Li cell with semi-aligned PAN@PVdF-HFP separator shows excellent cycling performance, good rate capability, as well as high discharge capacity.

Co9S8 nanoparticles embedded into amorphous carbon as anode materials for lithium-ion batteries.

In this paper, Co9S8 nanoparticles embedded into amorphous carbon have been synthesized by a simple electrospinning method followed by a high-temperature annealing process. The unique structure endows the Co9S8/C composites with excellent electrochemical properties. Co9S8 particles embedded into the carbon matrix show a high Li storage capacity around 1100 and 358 mAhg-1 at a current density of 0.1 and 5.0 Ag-1, respectively. After 200 cycles, an impressive discharge capacity of around 1063.4 mAhg-1 can be obtained at a current density of 0.3 Ag-1.

Solid-State, Low-Cost, and Green Synthesis and Robust Photochemical Hydrogen Evolution Performance of Ternary TiO2/MgTiO3/C Photocatalysts.

Solar-driven photochemical hydrogen evolution is a promising route to sustainable hydrogen fuel production. Large-scale preparation of highly active photocatalysts using elementally abundant and less-expensive materials is urgently required for widespread practical application. Here, we report a highly efficient and low-cost TiO2/MgTiO3/C heterostructure photocatalyst for photochemical water splitting, which was synthesized on gram scale via a facile mechanochemical method. The heterostructure and carbon sensitization offer excellent photoconversion efficiency as well as good photostability. Under irradiation of one AM 1.5G sunlight, the optimal TiO2/MgTiO3/C photocatalyst can show a great solar-driven hydrogen evolution rate (33.3 mmol·h-1·g-1), which is much higher than the best yields ever reported for MgTiO3-related photocatalysts or pure TiO2 (P-25). We hope this work will attract more attention to inspire further work by others for the development of low-cost, efficient, and robust photocatalysts for producing hydrogen in artificial photosynthetic systems.

Superior Sodium Storage of Carbon-Coated NaV6O15 Nanotube Cathode: Pseudocapacitance Versus Intercalation.

To realize the effect of Na+ pseudocapacitance on the sodium storage of cathode materials, clewlike carbon-coated sodium vanadium bronze (NaV6O15) nanotubes (Na-VBNT@C) were synthesized via a facile combined sol-gel/hydrothermal method. The resultant Na-VBNT@C delivers high reversible capacities of 209 and 105 mA h g-1 at the rates of 0.1 and 10 C, respectively. Notably, at the higher rate of 5 C (1250 mA g-1), it can retain 94% of the initial capacity after 3000 cycles. It was found that the outstanding rate performance and the long-term cycling life of Na-VBNT@C are primarily due to the Na+ pseudocapacitance. Our study reveals that the design of Na+ pseudocapacitance is beneficial for harvesting the superior performance of NaV6O15 cathode material in sodium-ion batteries.

Solid-phase synthesis of three-armed star-shaped peptoids and their hierarchical self-assembly.

Due to the branched structure feature and unique properties, a variety of star-shaped polymers have been designed and synthesized. Despite those advances, solid-phase synthesis of star-shaped sequence-defined synthetic polymers that exhibit hierarchical self-assembly remains a significant challenge. Hence, we present an effective strategy for the solid-phase synthesis of three-armed star-shaped peptoids, in which ethylenediamine was used as the centric star pivot. Based on the sequence of monomer addition, a series of AA'A''-type and ABB'-type peptoids were synthesized and characterized by UPLC-MS (ultrahigh performance liquid chromatography-mass spectrometry). By taking advantage of the easy-synthesis and large side-chain diversity, we synthesized star-shaped peptoids with tunable functions. We further demonstrated the aqueous self-assembly of some representative peptoids into biomimetic nanomaterials with well-defined hierarchical structures, such as nanofibers and nanotubes. These results indicate that star-shaped peptoids offer the potential in self-assembly of biomimetic nanomaterials with tunable chemistries and functions.

Palmitate enhanced the cytotoxicity of ZnO nanomaterials possibly by promoting endoplasmic reticulum stress.

We recently synthesized ZnO nanomaterials (denoted as ZnO nanorods [NRs] and Mini-NRs) and suggested that their cytotoxicity could be related with the activation of endoplasmic reticulum (ER) stress apoptosis. However, in a complex biological microenvironment, the ER stress-apoptosis pathway could also be modulated by biological molecules, such as free fatty acids, leading to unpredicted biological effects. In this study, we investigated the combined toxicity of ZnO NRs/Mini-NRs and palmitate (PA) to THP-1 macrophages. PA influenced the zeta potential and solubility of ZnO NRs and ZnO Mini-NRs in water, which indicated a change of colloidal stability. Exposure to ZnO NRs and Mini-NRs dose-dependent decreased cellular viability and release of soluble monocyte chemotactic protein 1 (sMCP-1), and these effects were significantly promoted with the presence of PA. However, ZnO NR- and Mini-NR-induced intracellular Zn ions or reactive oxygen species were not significantly affected by PA. ZnO NRs and ZnO Mini-NRs significantly promoted the expression of ER stress genes HSPA5, DDIT3, XBP-1s and apoptotic gene CASP3, whereas PA also modestly promoted the expression of HSPA5, DDIT3 and CASP3. Interestingly, the ER stress inducer thapsigargin showed a similar effect as PA to promote the cytotoxicity of ZnO NRs and ZnO Mini-NRs. It is suggested that PA might promote the cytotoxicity of ZnO NRs and ZnO Mini-NRs possibly by promoting ER stress.

Toxicity of ZnO nanoparticles (NPs) to THP-1 macrophages: interactions with saturated or unsaturated free fatty acids.

In a biological microenvironment, free fatty acids (FFA) as ubiquitous biological molecules might interact with nanoparticles (NPs) and consequently change the toxicological responses. However, whether the chemical structures of FFA could influence their interactions with NPs remain unknown. This study investigated the interactions between ZnO NPs and saturated or unsaturated FFA (complexed to BSA), namely stearic acid (SA, C18:0), oleic acid (OA, C18:1), and α-linolenic acid (ALA, C18:3). It was shown that BSA, SA, OA, and ALA increased the atomic force microscope (AFM) heights as well the polydispersity index (PDI) of ZnO NPs. BSA modestly protected THP-1 macrophages from ZnO NP exposure, whereas OA and ALA led to relatively less cyto-protective effects of BSA. Moreover, only co-exposure to ZnO NPs and SA significantly promoted the release of interleukin-8. BSA, SA, OA, and ALA equally changed intracellular ROS and Zn ions associated with ZnO exposure, but co-exposure to ZnO NPs and OA/ALA particularly activated the expression of endoplasmic reticulum stress-apoptosis genes. In combination, these results showed that FFA could influence the colloidal aspects and toxicological signaling pathway of ZnO NPs, which is dependent on the number of unsaturated bonds of FFA.

Influence of pristine and hydrophobic ZnO nanoparticles on cytotoxicity and endoplasmic reticulum (ER) stress-autophagy-apoptosis gene expression in A549-macrophage co-culture.

Exposure to ZnO nanoparticles (NPs) might modulate endoplasmic reticulum (ER) stress-autophagy gene expression, but the possible influence of hydrophobic surface coating on these responses was less studied. This study used A549-macrophage co-culture as the in vitro model for lung barrier and investigated the toxicity of pristine and hydrophobic ZnO NPs. Pristine and hydrophobic NPs exhibited different Zeta potential and solubility in water, which suggested that hydrophobic surface coating might alter the colloidal aspects of ZnO NPs. However, pristine and hydrophobic ZnO NPs induced cytotoxicity and reduced the release of soluble monocyte chemotactic protein-1 (sMCP-1) in A549-macrophage co-culture to a similar extent. Exposure to pristine ZnO NPs significantly promoted the expression of ER stress-apoptosis genes, namely DDIT3, XBP-1s, CASP9, CASP12 and BAX (p < 0.05), but hydrophobic ZnO NPs only significantly promoted the expression of BAX (p < 0.05). Exposure to pristine ZnO NPs also significantly reduced the expression of autophagic gene BECN1 (p < 0.05) but not ATG7 (p > 0.05), whereas hydrophobic ZnO NPs significantly reduced the expression of ATG7 and BECN1 (p < 0.01). Moreover, the expression of XBP-1s, HSPA5, CASP9, CASP12, BAX and ATG7 in pristine ZnO NP-exposed co-culture was significantly lower than that in hydrophobic ZnO NP-exposed co-culture (p < 0.05). In conclusion, hydrophobic surface coating might influence the colloidal aspects of ZnO NPs and alter ER stress-apoptosis-autophagy gene expression pattern by pristine ZnO NPs in A549-macrophage co-culture.

Temperature Effect on the Mechanical Properties of Electrospun PU Nanofibers.

Polyurethane (PU) nanofibers were prepared from electrospun method. Atomic force microscopy (AFM) was employed to characterize the mechanical properties of electrospun PU nanofibers. The impact of temperature on the mechanical behavior of PU nanofibers was studied using three-point bending test based on AFM. A Young's modulus of ~ 25 GPa was obtained for PU nanofibers with diameter at ~ 150 nm at room temperature. With decrease in nanofiber's diameter, the increasing Young's modulus can be due to the surface tension effect. The Young's modulus of the PU nanofiber decreased linearly while the fibrous morphology was maintained with the increase of temperature.

Strain-engineering tunable electron mobility of monolayer IV-V group compounds.

First-principles simulations demonstrate the anisotropic and high mobility in the new group monolayer IV-V semiconductors. The strain-engineered bandstructure reveals the conduction bands are sensitive to armchair-direction deformation. By applying strains, the electrical transportation in the armchair direction can be further improved or deteriorated. We use this important feature to achieve the tunable electron mobility in monolayer IV-V semiconductors. The controllable introduction of strain into semiconductors offers an important degree of flexibility in electrical transportation. Meanwhile, our works leads to a new approaches for research on mobility control in two-dimensional semiconductors. These will be useful for novel mechanical-electronic devices related to mobility switching.

Hierarchical C/SiO x /TiO2 ultrathin nanobelts as anode materials for advanced lithium ion batteries.

TiO2-based nanomaterials are demonstrated to be a promising candidate for next generation lithium ion batteries due to their stable performance and easy preparation. However, their inherent low capacity impedes their wide application compared to commercial carbon nanomaterials. Here we present a unique in situ grafting-graphitization method to achieve a ternary nanocomposite of C/SiO x /TiO2 ultrathin nanobelts with a core-shell heterostructure. The obtained ternary nanocomposite integrates the merits of high specific capacity of SiO x , the excellent mechanical stability of graphite-like carbon and the high reactivity of TiO2. Cyclic voltammetric curves and cycling performance manifest the optimal ternary nanocomposite and deliver a very high initial specific capacity of ∼1196 mA h g-1 with both good rate capability (∼200 mA h g-1 up to 10 C) and especially enhanced cycle stability. Our work demonstrates that building hierarchical core-shell heterostructures is an effective strategy to improve capacity and cycling performance in other composite anodes for electrochemical energy storage materials.

Influence of bovine serum albumin pre-incubation on toxicity and ER stress-apoptosis gene expression in THP-1 macrophages exposed to ZnO nanoparticles.

When entering a biological environment, proteins could be adsorbed onto nanoparticles (NPs), which can potentially influence the toxicity of NPs. This study used bovine serum albumin (BSA) as the model for serum protein and investigated its interactions with three different types of ZnO NPs, coded as XFI06 (pristine NPs of 20 nm), NM110 (pristine NPs of 100 nm) and NM111 (hydrophobic NPs of 130 nm). Atomic force microscope indicated the adsorption of BSA to ZnO NPs, leading to the increase of NP diameters. Pre-incubation with BSA did not significantly affect hydrodynamic size but decreased Zeta potential of NM110 and NM111. The fluorescence and synchronous fluorescence of BSA were quenched after pre-incubation with ZnO NPs, and the quenching effects were more obvious for XFI06 and NM110. Exposure to all types of ZnO NPs significantly induced cytotoxicity and lysosomal destabilization, which was slightly alleviated when NPs were pre-incubated with BSA. However, ZnO NPs with or without pre-incubation of BSA resulted in comparable intracellular Zn ions, glutathione and reactive oxygen species in THP-1 macrophages. Exposure to ZnO NPs promoted the expression of endoplasmic reticulum (ER) stress markers (DDIT3 and XBP-1s) and apoptosis genes (CASP9 and CASP12). Pre-incubation with BSA had minimal impact on ER stress gene expression but decreased apoptosis gene expression. Combined, these results suggested that pre-incubation with BSA could modestly alleviate the cytotoxicity and reduce ER stress related apoptosis gene expression in THP-1 macrophages after ZnO NP exposure.