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Phyllosilicates-based nanomaterials, particularly iron-rich vermiculite (VMT), have wide applications in biomedicine. However, the lack of effective methods to activate the functional layer covered by the external inert layer limits their future applications. Herein, we report a mineral phase reconfiguration strategy to prepare novel nanozymes by a molten salt method. The peroxidase-like activity of the VMT reconfiguration nanozyme is 10 times that of VMT, due to the electronic structure change of iron in VMT. Density-functional theory calculations confirmed that the upward shifted d-band center of the VMT reconfiguration nanozyme promoted the adsorption of H2O2 on the active iron sites and significantly elongated the O-O bond lengths. The reconfiguration nanozyme exhibited nearly 100% antibacterial activity toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), much higher than that of VMT (E. coli 10%, S. aureus 21%). This work provides new insights for the rational design of efficient bioactive phyllosilicates-based nanozyme.
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Escherichia coli , Staphylococcus aureus , Peróxido de Hidrógeno , Silicatos de Aluminio/farmacología , Hierro , Antibacterianos/farmacología , Antibacterianos/químicaRESUMEN
Fatal dendritic growth in lithium metal batteries is closely related to the composition and thickness of the modified separator. Herein, an ultrathin nanocoating composed of monolayer montmorillonite (MMT), poly(vinyl alcohol) (PVA) on a polypropylene separator is prepared. The MMT was exfoliated into monolayers (only 0.96 nm) by intercalating PVA under ultrasound, followed by cross-linking with glutaraldehyde. The thickness of the nanocoating on the polypropylene separator, as determined using the pull-up method, is only 200-500 nm with excellent properties. As a result, the lithium-symmetric battery composed of it has a low overpotential (only 40 mV) and a long lifespan of more than 7900 h at high current density, because ion transport is unimpeded and Li+ flows uniformly through the ordered ion channels between the MMT layers. Additionally, the separator exhibited excellent cycling stability in Li-S batteries. This study offers a new idea for fabricating ultrathin clay/polymer modified separators for metal anode stable cycling at high current densities.
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Dielectric polymer composites exhibit great application prospects in advanced pulse power systems and electric systems. However, the decline of breakdown strength by loading of single high dielectric constant nanofiller hinders the sustained increase in energy density of the composites. Here, a sandwich-structured nanocomposite prepared with mica nanosheets as the second filler exhibits decoupled modulation of dielectric constant and breakdown strength. The traditional layered clay mineral mica is exfoliated into nanosheets and filled into polyvinylidene difluoride (PVDF), which shows a special depolarization effect in the polymer matrix. In Kelvin probe microscopy characterization and thermally stimulated depolarization current indicates that the mica nanosheets provided space charge traps for the polymer matrix and effectively suppressed the carrier motion. A sandwich structure composite material with mica nanosheets as the central layer has achieved a high energy density of 11.48 J cm-3, 2.4 times higher than the pure PVDF film. This is due to the fact that randomly oriented distribution of nanosheets in a polymer matrix provide better current blocking. This work provides an effective method to improve the energy density of dielectric polymer composites by synergistically introducing insulating nanosheets and high dielectric constant nanofillers.
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Recent years have witnessed great research interests in developing high-performance electrocatalysts for the two-electron (2e-) oxygen reduction reaction (ORR) that enables the sustainable and flexible synthesis of H2O2. Carbon-based electrocatalysts exhibit attractive catalytic performance for the 2e- ORR, where oxygen-containing functional groups (OFGs) play a decisive role. However, current understanding is far from adequate, and the contribution of OFGs to the catalytic performance remains controversial. Therefore, a critical overview on OFGs in carbon-based electrocatalysts toward the 2e- ORR is highly desirable. Herein, we go over the methods for constructing OFGs in carbon including chemical oxidation, electrochemical oxidation, and precursor inheritance. Then we review the roles of OFGs in activating carbon toward the 2e- ORR, focusing on the intrinsic activity of different OFGs and the interplay between OFGs and metal species or defects. At last, we discuss the reasons for inconsistencies among different studies, and personal perspectives on the future development in this field are provided. The results provide insights into the origin of high catalytic activity and selectivity of carbon-based electrocatalysts toward the 2e- ORR and would provide theoretical foundations for the future development in this field.
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Overcoming the intrinsic low activity of most peroxidase mimics under neutral pH is crucial but still extremely challenging for the detection of disease markers in biological samples. Here, we chose nanoclay (i.e., montmorillonite K10, MK10) as a carrier to modulate the structure of Fe1-xS nanozyme components through an interfacial modulation strategy, aiming at breaking the neutral pH limitation of Fe1-xS. MK10 with abundant hydroxyl groups on its surface acts as a carrier to increase the ratio of Fe(II) and S(II-) content in surface Fe1-xS. We verify that Fe(II)-promoted surface hydroxyl radical generation and S(II-)-promoted regeneration of Fe(II) play key roles in endowing peroxidase-like activity to Fe1-xS at neutral pH. As expected, Fe1-xS/MK10 exhibited 11-fold higher Vmax and 52-fold higher catalytic efficiency than bare Fe1-xS. As a proof of concept, the sensor constructed based on Fe1-xS/MK10 achieved colorimetric detection of xanthine under neutral conditions with a linear range of 5-300 µM and a limit of detection of 2.49 µM. Finally, we achieved highly sensitive detection of xanthine in serum using the constructed biosensor. Our contribution is the novel use of a nanoclay-mediated interfacial modulation strategy for boosting the peroxidase-mimicking activity and breaking the pH limitation, which contributes to the in situ detection of disease markers by nanozymes under physiological conditions.
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Peroxidasa , Peroxidasas , Peroxidasa/química , Peroxidasas/química , Colorimetría , Concentración de Iones de Hidrógeno , Xantinas , Compuestos Ferrosos , Peróxido de HidrógenoRESUMEN
Lake sediments connection to the biogeochemical cycling of phosphorus (P) and carbon (C) influences streamwater quality. However, it is unclear whether and how the type of sediment controls P and C cycling in water. Here, the adsorption behavior of montmorillonite (Mt) with different interlayer cations (Na+, Ca2+, or Fe3+) on dissolved organic matter (DOM) and P was investigated to understand the role of Mt in regulating the organic carbon-to-phosphate (OC/P) ratio within freshwater systems. The adsorption capacity of Fe-Mt for P was 3.2-fold higher than that of Ca-Mt, while it was 1/3 lower for DOM. This dissimilarity in adsorption led to an increased OC/P in Fe-Mt-dominated water and a decreased OC/P in Ca-Mt-dominated water. Moreover, an in situ atomic force microscope and high-resolution mass spectrometry revealed molecular fractionation mechanisms and adsorptive processes. It was observed that DOM inhibited the nucleation and crystallization processes of P on the Mt surface, and P affected the binding energy of DOM on Mt through competitive adsorption, thereby governing the interfacial P/DOM dynamics on Mt substrates at a molecular level. These findings have important implications for water quality management, by highlighting the role of clay minerals as nutrient sinks and providing new strategies for controlling P and C dynamics in freshwater systems.
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Materia Orgánica Disuelta , Fósforo , Arcilla , Adsorción , Minerales/química , Lagos/química , CarbonoRESUMEN
To achieve a high separation efficiency of photogenerated carriers in semiconductors, constructing high-quality heterogeneous interfaces as charge flow highways is critical and challenging. This study successfully demonstrates an interfacial chemical bond and internal electric field (IEF) simultaneously modulated 0D/0D/1D-Co3 O4 /TiO2 /sepiolite composite catalyst by exploiting sepiolite surface-interfacial interactions to adjust the Co2+ /Co3+ ratio at the Co3 O4 /TiO2 heterointerface. In situ irradiation X-ray photoelectron spectroscopy and density functional theory (DFT) calculations reveal that the interfacial Co2+ OTi bond (compared to the Co3+ OTi bond) plays a major role as an atomic-level charge transport channel at the p-n junction. Co2+ /Co3+ ratio increase also enhances the IEF intensity. Therefore, the enhanced IEF cooperates with the interfacial Co2+ OTi bond to enhance the photoelectron separation and migration efficiency. A coupled photocatalysis-peroxymonosulfate activation system is used to evaluate the catalytic activity of Co3 O4 /TiO2 /sepiolite. Furthermore, this work demonstrates how efficiently separated photoelectrons facilitate the synergy between photocatalysis and peroxymonosulfate activation to achieve deep pollutant degradation and reduce its ecotoxicity. This study presents a new strategy for constructing high-quality heterogeneous interfaces by consciously modulating interfacial chemical bonds and IEF, and the strategy is expected to extend to this class of spinel-structured semiconductors.
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In recent decades, the concentration of dissolved organic matter (DOM) in aquatic ecosystems has gradually increased, leading to water pollution problems. Understanding the interfacial chemical processes of DOM on natural minerals is important to the exploration of high-efficiency absorbents. However, studying DOM chemical processes and adsorption mechanisms are still challenging due to the complex DOM structure and environmental system. Hence, we characterized the microstructure changes after the formation of amorphous calcium phosphate (ACP) at the interface of montmorillonite (Mt) minerals in a simulated environment system. Combined with atomic force microscopy and density functional theory (DFT) simulation, the mechanism of interfacial interaction between Mt-ACP and DOM was characterized at the molecular level. Moreover, we further evaluated the adsorption behavior of Mt-ACP as a potential adsorbent for organic matter. The comprehensive investigation of humic acid adsorption, intermolecular force, and DFT simulation is conducive to our understanding of the interfacial interaction mechanism between organic matter and noncrystalline minerals in aquatic environments and provides new perspectives on the application of clay-based mineral materials in pollutant removal under exposure from DOM.
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Local geometric configurations of metal cations in inorganic enzyme mimics determine their catalytic behaviors, while their optimization remains challenging. Herein, kaolinite, a naturally layered clay mineral, achieves the optimization of cationic geometric configuration in manganese ferrite. We demonstrate that the exfoliated kaolinite induces the formation of defective manganese ferrite and makes more iron cations fill into the octahedral sites, significantly enhancing the multiple enzyme-mimicking activities. The steady-state kinetic assay results show that the catalytic constant of composites toward 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 are more than 7.4- and 5.7-fold higher than manganese ferrite, respectively. Furthermore, density functional theory (DFT) calculations reveal that the outstanding enzyme-mimicking activity of composites is attributed to the optimized iron cation geometry configuration, which has a higher affinity and activation ability toward H2O2 and lowers the energy barrier of key intermediate formation. As a proof of concept, the novel structure with multiple enzyme-mimicking activities amplifies the colorimetric signal, realizing the ultrasensitive visual detection of disease marker acid phosphatase (ACP), with a detection limit of 0.25 mU/mL. Our findings provide a novel strategy for the rational design of enzyme mimics and an in-depth investigation of their enzyme-mimicking properties.
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Peróxido de Hidrógeno , Caolín , Minerales , Hierro , Colorimetría/métodosRESUMEN
The development of a high current density with high energy conversion efficiency electrocatalyst is vital for large-scale industrial application of alkaline water splitting, particularly seawater splitting. Herein, we design a self-supporting Co3(PO4)2-MoO3-x/CoMoO4/NF superaerophobic electrode with a three-dimensional structure for high-performance hydrogen evolution reaction (HER) by a reasonable devise of possible "Co-O-Mo hybridization" on the interface. The "Co-O-Mo hybridization" interfaces induce charge transfer and generation of fresh oxygen vacancy active sites. Consequently, the unique heterostructures greatly facilitate the dissociation process of H2O molecules and enable efficient hydrogen spillover, leading to excellent HER performance with ultralow overpotentials (76 and 130 mV at 100 and 500 mA cm-2) and long-term durability of 100 h in an alkaline electrolyte. Theoretical calculations reveal that the Co3(PO4)2-MoO3-x/CoMoO4/NF promotes the adsorption/dissociation process of H2O molecules to play a crucial role in improving the stability and activity of HER. Our results exhibit that the HER activity of non-noble metal electrocatalysts can be greatly enhanced by rational interfacial chemical bonding to modulate the heterostructures.
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Polar oxides are widely used as the cathodes to impede the shuttle effect in lithium-sulfur batteries, but suffer from the sluggish desorption and conversion of polysulfides due to too strong affinity of polysulfides on oxygen sites. Herein, employing halloysite as a model, an approach to overcome these shortcomings is proposed via engineering oxygen p-band center by loading titanium dioxide nanoparticles onto Si-O surface of halloysite. Using density functional theory calculations, it is predicted that electron transfer from titanium dioxide nanoparticles to interfacial O sites results in downshift of p-band center of O sites that promote desorption of polysulfides and the cleavage of Li-S and S-S, accelerating the conversion kinetics of polysulfides. The designed composite cathode material delivers outstanding electrochemical performance in Li-S batteries, outperforming the recently reported similar cathodes. The concept could provide valuable insight into the design of other catalysts for Li-S batteries and beyond.
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OBJECTIVE AND DESIGN: Retinoblastoma is the most common primary intraocular malignancy of childhood, which brings a heavy burden to the countries across the world, especially the developing countries. It has been shown that lncRNA muscleblind-like 1 antisense RNA 1 (MBNL1-AS1) exerts anti-tumor effects in various cancers, including bladder cancer, papillary thyroid cancer, and retinoblastoma. In the present study, we hypothesized that MBNL1-AS1 might play a protective role against retinoblastoma. METHODS: The expression of MBNL1-AS1 and its potential target miR-338-5p were evaluated in retinoblastoma cell line by real-time quantitative PCR and western blot. The involvement of MBNL1-AS1-miR-338-5p in the cell proliferation was evaluated by cell counting kit-8 (CCK8), and colony formation assay. The cell migration was evaluated by Transwell assay in Y79 cells, a retinoblastoma cell line. The involvement of MBNL1-AS1-miR-338-5p in tumor formation was also evaluated in mice. RESULTS: It was found that MBNL1-AS1 overexpression inhibited proliferation and migration in Y79 cells. In addition, the inhibitory effects of MBNL1-AS1 on Y79 cells were significantly reversed in the presence of miR-338-5p mimics, and MBNL1-AS1 overexpression significantly decreased miR-338-5p level in Y79 cells. Furthermore, MBNL1-AS1 overexpression significantly inhibited Wnt/ß-catenin signaling pathway, and this inhibitory effect was almost lost in the presence of miR-338-5p mimics. Finally, our in vivo study showed that MBNL1-AS1 overexpression significantly inhibited Y79-induced retinoblastoma in mice, and this inhibitory effect was lost in the presence of miR-338-5p mimics. CONCLUSION: Our study shows that MBNL1-AS1 exerts its anti-tumor effect by targeting miR-338-5p, thereby inactivating wnt/ß-catenin signaling pathway in retinoblastoma.
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MicroARNs , ARN Largo no Codificante , Neoplasias de la Retina/genética , Retinoblastoma/genética , Vía de Señalización Wnt , Animales , Línea Celular , Movimiento Celular , Proliferación Celular , Humanos , Ratones , Neoplasias de la Retina/metabolismo , Retinoblastoma/metabolismo , Cicatrización de HeridasRESUMEN
A glassy carbon electrode (GCE) was coated with N-doped carbon-modified palygorskite and used as an electrochemical sensor for determination of Pb(II) by differential pulse anodic stripping voltammetry. To obtain high reproducibility and sensitivity, optimum experimental conditions for lead deposition are studied. Voltammetric responses of the modified GCE prepared with different ratios of carbon and palygorskite are examined under same conditions. Compared with a bare GCE, a N-doped carbon modified/GCE and a bismuth-modified GCE, N-doped carbon-modified palygorskite greatly improves the performance of GCE. Response is the best and the interfacial impedance is minimized if the fraction of carbon coating is 31%. This indicates that its performance is due to the synergies between palygorskite and N-doped carbon. Figures of merit for the modified GCE include (a) a preconcentration time of 180 s, (b) a detection limit of 0.42 µg·L-1 (2σ criterion), and (c) a linear response in the 4.0 µg·L-1 to 10.0 mg·L-1 Pb(II) concentration range. The method is successfully applied to the determination of Pb(II) in spiked tape water and gives recoveries between 97.1 and 104.3%. Graphical abstract Schematic representation of different adsorption sites of Pb(II) and the optimal carbon content. The wide detection range is attributed to the synergetic effect of N-doped carbon modified palygorskite.
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Cr-MnOx/cordierite composites were prepared by Sol-gel, Impregnation, Co-precipitation and Rheological phase reaction method. Various technologies including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), thermogravimetry/differential scanning calorimetry (TG/DCS), and temperature-programmed reduction (TPR) were used to characterize the structure and morphology properties of the synthesized composites. The catalytic ability test of 1,2-dichlorobenzene (o-DCB) over the catalysts was conducted in a fixed-bed flow reactor with a gas hourly space velocity (GHSV) of 30,000 h-1 to investigate the catalytic performance of the prepared composites. The results indicated that the combined Cr2O3 and Mn2O3 phases supported on cordierite possessed a special ball-shaped and better redox property in the catalyst prepared by the Co-precipitation method with a Cr/Mn atomic ratio of 2â¶5, which was conducive to the increase of the synergistic effect and subsequently enhancement of the catalytic performance. Furthermore, it exhibited better stability within 60 h, which indicates a good prospect for industrial applications.
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The oxygen reduction reaction (ORR) via the two-electron pathway is an important method of hydrogen peroxide (H2O2) production. This study demonstrates that MnO with different oxygen vacancies possesses great 2e- ORR activity. The H2O2 selectivity increased from 10% to 93% with increasing oxygen vacancy concentration by adjusting the reaction temperature and time. Moreover, the H2O2 yield of the optimal MnO reached 544.1 mmol g-1 h-1, and it showed extraordinary stability over a long period of time (10 000 circles CV), surpassing most of the reported transition metal catalysts. This provides a new strategy for efficient and low-cost electrochemical production of H2O2.
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A Fe(III) intercalated montmorillonite nanoplatform (Fe-MMT) was engineered for doxorubicin (DOX) loading. The constructed Fe-MMT/DOX nanoplatform could not only improve the production of H2O2 to enhance chemodynamic therapy but interfere with DNA damage repair to amplify the efficacy of DOX, proving an ideal combination of chemotherapy and chemodynamic therapy.
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Compuestos Férricos , Neoplasias , Humanos , Arcilla , Peróxido de Hidrógeno , Doxorrubicina/farmacología , Línea Celular TumoralRESUMEN
Although various excellent electrocatalysts/adsorbents have made notable progress as sulfur cathode hosts on the lithium-sulfur (Li-S) coin-cell level, high energy density (WG ) of the practical Li-S pouch cells is still limited by inefficient Li-ion transport in the thick sulfur cathode under low electrolyte/sulfur (E/S) and negative/positive (N/P) ratios, which aggravates the shuttle effect and sluggish redox kinetics. Here a new ternary fluoride MgAlF5 ·2H2 O with ultrafast ion conduction-strong polysulfides capture integration is developed. MgAlF5 ·2H2 O has an inverse Weberite-type crystal framework, in which the corner-sharing [AlF6 ]-[MgF4 (H2 O)2 ] octahedra units extend to form two-dimensional Li-ion transport channels along the [100] and [010] directions, respectively. Applied as the cathode sulfur host, the MgAlF5 ·2H2 O lithiated by LiTFSI (lithium salt in Li-S electrolyte) acts as a fast ionic conductor to ensure efficient Li-ion transport to accelerate the redox kinetics under high S loadings and low E/S and N/P. Meanwhile, the strong polar MgAlF5 ·2H2 O captures polysulfides by chemisorption to suppress the shuttle effect. Therefore, a 1.97 A h-level Li-S pouch cell achieves a high WG of 386 Wh kg-1 . This work develops a new-type ionic conductor, and provides unique insights and new hosts for designing practical Li-S pouch cells.
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The slow Li+ transport rate in the thick sulfur cathode of the Li-S battery affects its capacity and cycling performance. Herein, Fe-doped highly ordered mesoporous silica material (Fe-HSBA-15) as a sulfur carrier of the Li-S battery shows high ion conductivity (1.10 mS cm-1) and Li+ transference number (0.77). The Fe-HSBA-15/S cell has an initial capacity of up to 1216.7 mA h g-1 at 0.2C and good stability. Impressively, at a high sulfur load of 4.34 mg cm-2, the Fe-HSBA-15/S cell still maintains an area specific capacity of 4.47 mA h cm-2 after 100 cycles. This is because Fe-HSBA-15 improves the Li+ diffusion behavior through the ordered mesoporous structure. Theoretical calculations also confirmed that the doping of iron enhances the adsorption of polysulfides, reduces the band gap and makes the catalytic activity stronger.
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Sodium metal is one of the most promising anodes for the prospective low-cost rechargeable batteries. Nevertheless, the commercialization of Na metal anodes remains restricted by sodium dendrite growth. Herein, halloysite nanotubes (HNTs) were chosen as the insulated scaffolds, and Ag nanoparticles were introduced as sodiophilic sites to achieve uniform sodium deposition from bottom to top under the synergistic effect. Density functional theory (DFT) calculation results demonstrated that the presence of Ag greatly increased the binding energy of sodium on HNTs/Ag (-2.85 eV) vs HNTs (-0.85 eV). Meanwhile, thanks to the opposite charges on the inner and outer surfaces of HNTs, faster Na+ transfer kinetics and selective adsorption of SO3CF3- on the inner surface of HNTs were achieved, thus avoiding the formation of space charge. Accordingly, the coordination between HNTs and Ag afforded a high Coulombic efficiency (about 99.6% at 2 mA cm-2), long lifespan in a symmetric battery (for over 3500 h at 1 mA cm-2), and remarkable cycle stability in Na metal full batteries. This work offers a novel strategy to design a sodiophilic scaffold by nanoclay for dendrite-free Na metal anodes.
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Here, we demonstrate a new electrochemical sensing mechanism of ammonium ions (NH4+) involving a two-electron oxygen reduction reaction (ORR) and a hydrazine reaction. The NH4+ are electrooxidized to hydrazine by H2O2 derived from the ORR over a self-supporting Ag/TiO2 nanotube array composite electrode modified by hematite (Ag/Fe2O3/TNTs). The Ag/Fe2O3/TNT sensor exhibits a high sensitivity of 1876 µA mM-1 cm-2 with a detection limit of 0.18 µM under non-alkaline conditions, a short response time of 3 s, good reproducibility, and fine selectivity among various interferents, and is also successfully used in real water bodies to display high accuracy. Furthermore, this new mechanism has a certain universality in a range of Ag (main catalyst)/transition metal oxide (cocatalyst)/TNT sensing systems. This work offers a new design basis for the urgently needed electrochemical ammonia nitrogen sensors.