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1.
Cell ; 175(7): 1769-1779.e13, 2018 12 13.
Artículo en Inglés | MEDLINE | ID: mdl-30392960

RESUMEN

The fluid-mosaic model posits a liquid-like plasma membrane, which can flow in response to tension gradients. It is widely assumed that membrane flow transmits local changes in membrane tension across the cell in milliseconds, mediating long-range signaling. Here, we show that propagation of membrane tension occurs quickly in cell-attached blebs but is largely suppressed in intact cells. The failure of tension to propagate in cells is explained by a fluid dynamical model that incorporates the flow resistance from cytoskeleton-bound transmembrane proteins. Perturbations to tension propagate diffusively, with a diffusion coefficient Dσ ∼0.024 µm2/s in HeLa cells. In primary endothelial cells, local increases in membrane tension lead only to local activation of mechanosensitive ion channels and to local vesicle fusion. Thus, membrane tension is not a mediator of long-range intracellular signaling, but local variations in tension mediate distinct processes in sub-cellular domains.


Asunto(s)
Membrana Celular/metabolismo , Citoesqueleto/metabolismo , Canales Iónicos/metabolismo , Modelos Biológicos , Transducción de Señal/fisiología , Animales , Perros , Células HeLa , Humanos , Células de Riñón Canino Madin Darby , Ratones , Células 3T3 NIH , Ratas
2.
Proc Natl Acad Sci U S A ; 121(29): e2320962121, 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-38980904

RESUMEN

Turbulent flows have been used for millennia to mix solutes; a familiar example is stirring cream into coffee. However, many energy, environmental, and industrial processes rely on the mixing of solutes in porous media where confinement suppresses inertial turbulence. As a result, mixing is drastically hindered, requiring fluid to permeate long distances for appreciable mixing and introducing additional steps to drive mixing that can be expensive and environmentally harmful. Here, we demonstrate that this limitation can be overcome just by adding dilute amounts of flexible polymers to the fluid. Flow-driven stretching of the polymers generates an elastic instability, driving turbulent-like chaotic flow fluctuations, despite the pore-scale confinement that prohibits typical inertial turbulence. Using in situ imaging, we show that these fluctuations stretch and fold the fluid within the pores along thin layers ("lamellae") characterized by sharp solute concentration gradients, driving mixing by diffusion in the pores. This process results in a [Formula: see text] reduction in the required mixing length, a [Formula: see text] increase in solute transverse dispersivity, and can be harnessed to increase the rate at which chemical compounds react by [Formula: see text]-enhancements that we rationalize using turbulence-inspired modeling of the underlying transport processes. Our work thereby establishes a simple, robust, versatile, and predictive way to mix solutes in porous media, with potential applications ranging from large-scale chemical production to environmental remediation.

3.
Proc Natl Acad Sci U S A ; 121(12): e2316723121, 2024 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-38478686

RESUMEN

Many environmental and industrial processes depend on how fluids displace each other in porous materials. However, the flow dynamics that govern this process are still poorly understood, hampered by the lack of methods to measure flows in optically opaque, microscopic geometries. We introduce a 4D microvelocimetry method based on high-resolution X-ray computed tomography with fast imaging rates (up to 4 Hz). We use this to measure flow fields during unsteady-state drainage, injecting a viscous fluid into rock and filter samples. This provides experimental insight into the nonequilibrium energy dynamics of this process. We show that fluid displacements convert surface energy into kinetic energy. The latter corresponds to velocity perturbations in the pore-scale flow field behind the invading fluid front, reaching local velocities more than 40 times faster than the constant pump rate. The characteristic length scale of these perturbations exceeds the characteristic pore size by more than an order of magnitude. These flow field observations suggest that nonlocal dynamic effects may be long-ranged even at low capillary numbers, impacting the local viscous-capillary force balance and the representative elementary volume. Furthermore, the velocity perturbations can enhance unsaturated dispersive mixing and colloid transport and yet, are not accounted for in current models. Overall, this work shows that 4D X-ray velocimetry opens the way to solve long-standing fundamental questions regarding flow and transport in porous materials, underlying models of, e.g., groundwater pollution remediation and subsurface storage of CO2 and hydrogen.

4.
Proc Natl Acad Sci U S A ; 121(22): e2401656121, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38787880

RESUMEN

Understanding the dynamics of electric-double-layer (EDL) charging in porous media is essential for advancements in next-generation energy storage devices. Due to the high computational demands of direct numerical simulations and a lack of interfacial boundary conditions for reduced-order models, the current understanding of EDL charging is limited to simple geometries. Here, we present a network model to predict EDL charging in arbitrary networks of long pores in the Debye-Hückel limit without restrictions on EDL thickness and pore radii. We demonstrate that electrolyte transport is described by Kirchhoff's laws in terms of the electrochemical potential of charge (the valence-weighted average of the ion electrochemical potentials) instead of the electric potential. By employing the equivalent circuit representation suggested by these modified Kirchhoff's laws, our methodology accurately captures the spatial and temporal dependencies of charge density and electric potential, matching results obtained from computationally intensive direct numerical simulations. Our network model provides results up to six orders of magnitude faster, enabling the efficient simulation of a triangular lattice of five thousand pores in 6 min. We employ the framework to study the impact of pore connectivity and polydispersity on electrode charging dynamics for pore networks and discuss how these factors affect the time scale, energy density, and power density of capacitive charging. The scalability and versatility of our methodology make it a rational tool for designing 3D-printed electrodes and for interpreting geometric effects on electrode impedance spectroscopy measurements.

5.
Proc Natl Acad Sci U S A ; 121(5): e2320237121, 2024 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-38252821

RESUMEN

Dynamic 3D covalent organic frameworks (COFs) have shown concerted structural transformation and adaptive gas adsorption due to the conformational diversity of organic linkers. However, the isolation and observation of COF rotamers constitute undergoing challenges due to their comparable free energy and subtle rotational energy barrier. Here, we report the atomic-level observation and structural evolution of COF rotamers by cryo-3D electron diffraction and synchrotron powder X-ray diffraction. Specifically, we optimize the crystallinity and morphology of COF-320 to manifest its coherent dynamic responses upon adaptive inclusion of guest molecules. We observe a significant crystal expansion of 29 vol% upon hydration and a giant swelling with volume change up to 78 vol% upon solvation. We record the structural evolution from a non-porous contracted phase to two narrow-pore intermediate phases and the fully opened expanded phase using n-butane as a stabilizing probe at ambient conditions. We uncover the rotational freedom of biphenylene giving rise to significant conformational changes on the diimine motifs from synclinal to syn-periplanar and anticlinal rotamers. We illustrate the 10-fold increment of pore volumes and 100% enhancement of methane uptake capacity of COF-320 at 100 bar and 298 K. The present findings shed light on the design of smarter organic porous materials to maximize host-guest interaction and boost gas uptake capacity through progressive structural transformation.

6.
Proc Natl Acad Sci U S A ; 121(1): e2305890120, 2024 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-38147554

RESUMEN

Slow multiphase flow in porous media is intriguing because its underlying dynamics is almost deterministic, yet depends on a hierarchy of spatiotemporal processes. There has been great progress in the experimental study of such multiphase flows, but three-dimensional (3D) microscopy methods probing the pore-scale fluid dynamics with millisecond resolution have been lacking. Yet, it is precisely at these length and time scales that the crucial pore-filling events known as Haines jumps take place. Here, we report four-dimensional (4D) (3D + time) observations of multiphase flow in a consolidated porous medium as captured in situ by stroboscopic X-ray micro-tomography. With a total duration of 6.5 s and 2 kHz frame rate, our experiments provide unprecedented access to the multiscale liquid dynamics. Our tomography strategy relies on the fact that Haines jumps, although irregularly spaced in time, are almost deterministic, and therefore repeatable during imbibition-drainage cycling. We studied the time-dependent flow pattern in a porous medium consisting of sintered glass shards. Exploiting the repeatability, we could combine the radiographic projections recorded under different angles during successive cycles into a 3D movie, allowing us to reconstruct pore-scale events, such as Haines jumps, with a spatiotemporal resolution that is two orders of magnitude higher than was hitherto possible. This high resolution allows us to explore the detailed interfacial dynamics during drainage, including fluid-front displacements and velocities. Our experimental approach opens the way to the study of fast, yet deterministic mesoscopic processes also other than flow in porous media.

7.
Proc Natl Acad Sci U S A ; 121(11): e2317440121, 2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38437532

RESUMEN

Silicone-based elastomers (SEs) have been extensively applied in numerous cutting-edge areas, including flexible electronics, biomedicine, 5G smart devices, mechanics, optics, soft robotics, etc. However, traditional strategies for the synthesis of polymer elastomers, such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization, are inevitably restricted by long-time usage, organic solvent additives, high energy consumption, and environmental pollution. Here, we propose a Joule heating chemistry method for ultrafast universal fabrication of SEs with configurable porous structures and tunable components (e.g., graphene, Ag, graphene oxide, TiO2, ZnO, Fe3O4, V2O5, MoS2, BN, g-C3N4, BaCO3, CuI, BaTiO3, polyvinylidene fluoride, cellulose, styrene-butadiene rubber, montmorillonite, and EuDySrAlSiOx) within seconds by only employing H2O as the solvent. The intrinsic dynamics of the in situ polymerization and porosity creation of these SEs have been widely investigated. Notably, a flexible capacitive sensor made from as-fabricated silicone-based elastomers exhibits a wide pressure range, fast responses, long-term durability, extreme operating temperatures, and outstanding applicability in various media, and a wireless human-machine interaction system used for rescue activities in extreme conditions is established, which paves the way for more polymer-based material synthesis and wider applications.

8.
Proc Natl Acad Sci U S A ; 120(50): e2310584120, 2023 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-38048464

RESUMEN

We present a comprehensive description of the aspect ratio impact on interfacial instability in porous media where a wetting liquid displaces a nonwetting fluid. Building on microfluidic experiments, we evidence imbibition scenarios yielding interfacial instabilities and macroscopic morphologies under different depth confinements, which were controlled by aspect ratio and capillary number. We report a phenomenon whereby a smaller aspect ratio of depth-variable microfluidic porous media and lower capillary number trigger interfacial instability during forced imbibition; otherwise, a larger aspect ratio of uniform-depth microfluidic porous media and higher capillary number will suppress the interfacial instability, which seemingly ignored or contradicts conventional expectations with compact and faceted growth during imbibition. Pore-scale theoretical analytical models, numerical simulations, as well as microfluidic experiments were combined for characteristics of microscopic interfacial dynamics and macroscopic displacement results as a function of aspect ratio, depth variation, and capillary number. Our results present a complete dynamic view of the imbibition process over a full range of regimes from interfacial stabilization to destabilization. We predict the mode of imbibition in porous media based on pore-scale interfacial behavior, which fits well with microfluidic experiments. The study provides insights into the role of aspect ratio in controlling interfacial instabilities in microfluidic porous media. The finding provides design or prediction principles for engineered porous media, such as microfluidic devices, membranes, fabric, exchange columns, and even soil and rocks concerning their desired immiscible imbibition behavior.

9.
Proc Natl Acad Sci U S A ; 120(30): e2302561120, 2023 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-37467270

RESUMEN

Metal-organic frameworks (MOFs), which possess a high degree of crystallinity and a large surface area with tunable inorganic nodes and organic linkers, exhibit high stimuli-responsiveness and molecular adsorption selectivity that enable various applications. The adsorption in MOFs changes the crystalline structure and elastic moduli. Thus, the coexistence of adsorbed/desorbed sites makes the host matrices elastically heterogeneous. However, the role of elastic heterogeneity in the adsorption-desorption transition has been overlooked. Here, we show the asymmetric role of elastic heterogeneity in the adsorption-desorption transition. We construct a minimal model incorporating adsorption-induced lattice expansion/contraction and an increase/decrease in the elastic moduli. We find that the transition is hindered by the entropic and energetic effects which become asymmetric in the adsorption process and desorption process, leading to the strong hysteretic nature of the transition. Furthermore, the adsorbed/desorbed sites exhibit spatially heterogeneous domain formation, implying that the domain morphology and interfacial area between adsorbed/desorbed sites can be controlled by elastic heterogeneity. Our results provide a theoretical guideline for designing soft porous crystals with tunable adsorption hysteresis and the dispersion and domain morphology of adsorbates using elastic heterogeneity.

10.
Proc Natl Acad Sci U S A ; 120(19): e2222050120, 2023 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-37126692

RESUMEN

Porous carbon is a pivotal material for electrochemical applications. The manufacture of porous carbon has relied on chemical treatments (etching or template) that require processing in all areas of the carbon/carbon precursor. We present a unique approach to preparing porous carbon nanospheres by inhibiting the pyrolytic condensation of polymers. Specifically, the porous carbon nanospheres are obtained by coating a thin film of ZnO on polystyrene spheres. The porosity of the porous carbon nanospheres is controlled by the thickness of the ZnO shell, achieving a BET-specific area of 1,124 m2/g with a specific volume of 1.09 cm3/g. We confirm that under the support force by the ZnO shell, a hierarchical pore structure in which small mesopores are connected by large mesopores is formed and that the pore-associated sp3 defects are enriched. These features allow full utilization of the surface area of the carbon pores. The electrochemical capacitive performance of porous carbon nanospheres was evaluated, achieving a high capacitance of 389 F/g at 1 A/g, capacitance retention of 71% at a 20-fold increase in current density, and stability up to 30,000 cycles. In particular, we achieve a specific area-normalized capacitance of 34.6 µF/cm2, which overcomes the limitations of conventional carbon materials.

11.
Proc Natl Acad Sci U S A ; 120(42): e2312091120, 2023 Oct 17.
Artículo en Inglés | MEDLINE | ID: mdl-37812706

RESUMEN

Metal-sulfur batteries have received great attention for electrochemical energy storage due to high theoretical capacity and low cost, but their further development is impeded by low sulfur utilization, poor electrochemical kinetics, and serious shuttle effect of the sulfur cathode. To avoid these problems, herein, a triple-synergistic small-molecule sulfur cathode is designed by employing N, S co-doped hierarchical porous bamboo charcoal as a sulfur host in an aqueous Cu-S battery. Expect the enhanced conductivity and chemisorption induced by N, S synergistic co-doping, the intrinsic synergy of macro-/meso-/microporous triple structure also ensures space-confined small-molecule sulfur as high utilization reactant and effectively alleviates the volume expansion during conversion reaction. Under a further joint synergy between hierarchical structure and heteroatom doping, the resulting sulfur cathode endows the Cu-S battery with outstanding electrochemical performance. Cycled at 5 A g-1, it can deliver a high reversible capacity of 2,509.8 mAh g-1 with a good capacity retention of 97.9% after 800 cycles. In addition, a flexible hybrid pouch cell built by a small-molecule sulfur cathode, Zn anode, and gel electrolytes can firmly deliver high average operating voltage of about 1.3 V with a reversible capacity of over 2,500 mAh g-1 under various destructive conditions, suggesting that the triple-synergistic small-molecule sulfur cathode promises energetic metal-sulfur batteries.

12.
Proc Natl Acad Sci U S A ; 119(30): e2122202119, 2022 07 26.
Artículo en Inglés | MEDLINE | ID: mdl-35858419

RESUMEN

Bacteria in porous media, such as soils, aquifers, and filters, often form surface-attached communities known as biofilms. Biofilms are affected by fluid flow through the porous medium, for example, for nutrient supply, and they, in turn, affect the flow. A striking example of this interplay is the strong intermittency in flow that can occur when biofilms nearly clog the porous medium. Intermittency manifests itself as the rapid opening and slow closing of individual preferential flow paths (PFPs) through the biofilm-porous medium structure, leading to continual spatiotemporal rearrangement. The drastic changes to the flow and mass transport induced by intermittency can affect the functioning and efficiency of natural and industrial systems. Yet, the mechanistic origin of intermittency remains unexplained. Here, we show that the mechanism driving PFP intermittency is the competition between microbial growth and shear stress. We combined microfluidic experiments quantifying Bacillus subtilis biofilm formation and behavior in synthetic porous media for different pore sizes and flow rates with a mathematical model accounting for flow through the biofilm and biofilm poroelasticity to reveal the underlying mechanisms. We show that the closing of PFPs is driven by microbial growth, controlled by nutrient mass flow. Opposing this, we find that the opening of PFPs is driven by flow-induced shear stress, which increases as a PFP becomes narrower due to microbial growth, causing biofilm compression and rupture. Our results demonstrate that microbial growth and its competition with shear stresses can lead to strong temporal variability in flow and transport conditions in bioclogged porous media.


Asunto(s)
Bacillus subtilis , Biopelículas , Estrés Mecánico , Bacillus subtilis/crecimiento & desarrollo , Medios de Cultivo , Modelos Teóricos , Porosidad
13.
Proc Natl Acad Sci U S A ; 119(40): e2209607119, 2022 10 04.
Artículo en Inglés | MEDLINE | ID: mdl-36161889

RESUMEN

Blood stream infections (BSIs) cause high mortality, and their rapid detection remains a significant diagnostic challenge. Timely and informed administration of antibiotics can significantly improve patient outcomes. However, blood culture, which takes up to 5 d for a negative result, followed by PCR remains the gold standard in diagnosing BSI. Here, we introduce a new approach to blood-based diagnostics where large blood volumes can be rapidly dried, resulting in inactivation of the inhibitory components in blood. Further thermal treatments then generate a physical microscale and nanoscale fluidic network inside the dried matrix to allow access to target nucleic acid. The amplification enzymes and primers initiate the reaction within the dried blood matrix through these networks, precluding any need for conventional nucleic acid purification. High heme background is confined to the solid phase, while amplicons are enriched in the clear supernatant (liquid phase), giving fluorescence change comparable to purified DNA reactions. We demonstrate single-molecule sensitivity using a loop-mediated isothermal amplification reaction in our platform and detect a broad spectrum of pathogens, including gram-positive methicillin-resistant and methicillin-susceptible Staphylococcus aureus bacteria, gram-negative Escherichia coli bacteria, and Candida albicans (fungus) from whole blood with a limit of detection (LOD) of 1.2 colony-forming units (CFU)/mL from 0.8 to 1 mL of starting blood volume. We validated our assay using 63 clinical samples (100% sensitivity and specificity) and significantly reduced sample-to-result time from over 20 h to <2.5 h. The reduction in instrumentation complexity and costs compared to blood culture and alternate molecular diagnostic platforms can have broad applications in healthcare systems in developed world and resource-limited settings.


Asunto(s)
ADN Bacteriano , ADN de Hongos , Pruebas con Sangre Seca , Reacción en Cadena de la Polimerasa , Sepsis , Antibacterianos/farmacología , Candida albicans/genética , Candida albicans/aislamiento & purificación , ADN Bacteriano/sangre , ADN de Hongos/sangre , Pruebas con Sangre Seca/métodos , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Hemo/química , Humanos , Límite de Detección , Meticilina/farmacología , Reacción en Cadena de la Polimerasa/métodos , Sensibilidad y Especificidad , Sepsis/sangre , Sepsis/diagnóstico , Sepsis/microbiología , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificación , Células Madre
14.
Nano Lett ; 2024 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-38592087

RESUMEN

Electroactive artificial muscles with deformability have attracted widespread interest in the field of soft robotics. However, the design of artificial muscles with low-driven voltage and operational durability remains challenging. Herein, novel biomass porous carbon (BPC) electrodes are proposed. The nanoporous BPC enables the electrode to provide exposed active surfaces for charge transfer and unimpeded channels for ion migration, thus decreasing the driving voltage, enhancing time durability, and maintaining the actuation performances simultaneously. The proposed actuator exhibits a high displacement of 13.6 mm (bending strain of 0.54%) under 0.5 V and long-term durability of 99.3% retention after 550,000 cycles (∼13 days) without breaks. Further, the actuators are integrated to perform soft touch on a smartphone and demonstrated as bioinspired robots, including a bionic butterfly and a crawling robot (moving speed = 0.08 BL s-1). This strategy provides new insight into the design and fabrication of high-performance electroactive soft actuators with great application potential.

15.
Nano Lett ; 24(4): 1284-1293, 2024 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-38230643

RESUMEN

Despite its effectiveness in eliminating cancer cells, ferroptosis is hindered by the high natural antioxidant glutathione (GSH) levels in the tumor microenvironment. Herein, we developed a spatially asymmetric nanoparticle, Fe3O4@DMS&PDA@MnO2-SRF, for enhanced ferroptosis. It consists of two subunits: Fe3O4 nanoparticles coated with dendritic mesoporous silica (DMS) and PDA@MnO2 (PDA: polydopamine) loaded with sorafenib (SRF). The spatial isolation of the Fe3O4@DMS and PDA@MnO2-SRF subunits enhances the synergistic effect between the GSH-scavengers and ferroptosis-related components. First, the increased exposure of the Fe3O4 subunit enhances the Fenton reaction, leading to increased production of reactive oxygen species. Furthermore, the PDA@MnO2-SRF subunit effectively depletes GSH, thereby inducing ferroptosis by the inactivation of glutathione-dependent peroxidases 4. Moreover, the SRF blocks Xc- transport in tumor cells, augmenting GSH depletion capabilities. The dual GSH depletion of the Fe3O4@DMS&PDA@MnO2-SRF significantly weakens the antioxidative system, boosting the chemodynamic performance and leading to increased ferroptosis of tumor cells.


Asunto(s)
Ferroptosis , Nanopartículas , Neoplasias , Humanos , Compuestos de Manganeso/farmacología , Óxidos , Antioxidantes , Glutatión , Dióxido de Silicio , Línea Celular Tumoral , Neoplasias/tratamiento farmacológico , Microambiente Tumoral
16.
Nano Lett ; 24(28): 8752-8762, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-38953881

RESUMEN

Acute methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is a common and serious lung infection with high morbidity and mortality rates. Due to the increasing antibiotic resistance, toxicity, and pathogenicity of MRSA, there is an urgent need to explore effective antibacterial strategies. In this study, we developed a dry powder inhalable formulation which is composed of porous microspheres prepared from poly(lactic-co-glycolic acid) (PLGA), internally loaded with indocyanine green (ICG)-modified, heat-resistant phages that we screened for their high efficacy against MRSA. This formulation can deliver therapeutic doses of ICG-modified active phages to the deep lung tissue infection sites, avoiding rapid clearance by alveolar macrophages. Combined with the synergistic treatment of phage therapy and photothermal therapy, the formulation demonstrates potent bactericidal effects in acute MRSA pneumonia. With its long-term stability at room temperature and inhalable characteristics, this formulation has the potential to be a promising drug for the clinical treatment of MRSA pneumonia.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Animales , Ratones , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , Microesferas , Terapia Fototérmica , Neumonía Estafilocócica/terapia , Terapia de Fagos/métodos , Verde de Indocianina/química , Verde de Indocianina/farmacología , Verde de Indocianina/uso terapéutico , Verde de Indocianina/administración & dosificación , Antibacterianos/química , Antibacterianos/farmacología , Antibacterianos/administración & dosificación , Antibacterianos/uso terapéutico , Administración por Inhalación , Humanos , Bacteriófagos/química
17.
Nano Lett ; 24(28): 8558-8566, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-38847360

RESUMEN

In laser-based additive manufacturing (AM), porosity and unmelted metal powder are typically considered undesirable and harmful. Nevertheless in this work, precisely controlling laser parameters during printing can intentionally introduce controllable porosity, yielding a porous electrode with enhanced catalytic activity for the oxygen evolution reaction (OER). This study demonstrates that deliberate introduction of porosity, typically considered a defect, leads to improved gas molecule desorption, enhanced mass transfer, and increased catalytically active sites. The optimized P-93% electrode displays superior OER performance with an overpotential of 270 mV at 20 mA cm-2. Furthermore, it exhibits remarkable long-term stability, operating continuously for over 1000 h at 10 mA cm-2 and more than 500 h at 500 mA cm-2. This study not only provides a straightforward and mass-producible method for efficient, binder-free OER catalysts but also, if optimized, underscores the potential of laser-based AM driven defect engineering as a promising strategy for industrial water splitting.

18.
Nano Lett ; 24(10): 3196-3203, 2024 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-38437624

RESUMEN

Gelation is a promising method to assemble 3D macroscopic structures from MXene sheets for various applications. However, the fine control and scalable manufacturing of 3D MXene monoliths remains a great challenge. Herein, the controllable gelation of Ti3C2Tx MXene initiated by various ionic liquids (ILs) is first proposed, where the IL serve as linkers to bond the nanosheets together through electrostatic and hydrogen bonding interactions, forming 3D monoliths with well-adjustable structure. Furthermore, density functional theory calculations and experiments further reveal the cross-linking effect of different ILs. Typically, 3D porous structure with high specific surface area, suitable pore size, and improved electrolyte affinity is designed through the cross-linking of Ti3C2Tx with 1-vinyl-3-ethylimidazole bromide ([C2VIm]Br-Ti3C2Tx). Due to the strong coupling, the as-synthesized monolith possesses excellent rate performance and high energy density. The methodology is quite flexible, controllable, and universal that provides a new perspective for promoting innovative applications of 2D materials.

19.
Nano Lett ; 2024 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-38842262

RESUMEN

The integration of nanotechnology with photoredox medicine has led to the emergence of biocompatible semiconducting polymer nanoparticles (SPNs) for the optical modulation of intracellular reactive oxygen species (ROS). However, the need for efficient photoactive materials capable of finely controlling the intracellular redox status with high spatial resolution at a nontoxic light density is still largely unmet. Herein, highly photoelectrochemically efficient photoactive polymer beads are developed. The photoactive material/electrolyte interfacial area is maximized by designing porous semiconducting polymer nanoparticles (PSPNs). PSPNs are synthesized by selective hydrolysis of the polyester segments of nanoparticles made of poly(3-hexylthiophene)-graft-poly(lactic acid) (P3HT-g-PLA). The photocurrent of PSPNs is 4.5-fold higher than that of nonporous P3HT-g-PLA-SPNs, and PSPNs efficiently reduce oxygen in an aqueous environment. PSPNs are internalized within endothelial cells and optically trigger ROS generation with a >1.3-fold concentration increase with regard to nonporous P3HT-SPNs, at a light density as low as a few milliwatts per square centimeter, fully compatible with in vivo, chronic applications.

20.
Mol Med ; 30(1): 24, 2024 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-38321393

RESUMEN

BACKGROUND: Lipid peroxidation is a characteristic metabolic manifestation of diabetic retinopathy (DR) that causes inflammation, eventually leading to severe retinal vascular abnormalities. Selenium (Se) can directly or indirectly scavenge intracellular free radicals. Due to the narrow distinction between Se's effective and toxic doses, porous Se@SiO2 nanospheres have been developed to control the release of Se. They exert strong antioxidant and anti-inflammatory effects. METHODS: The effect of anti-lipid peroxidation and anti-inflammatory effects of porous Se@SiO2 nanospheres on diabetic mice were assessed by detecting the level of Malondialdehyde (MDA), glutathione peroxidase 4 (GPX4), decreased reduced/oxidized glutathione (GSH/GSSG) ratio, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL) -1ß of the retina. To further examine the protective effect of porous Se@SiO2 nanospheres on the retinal vasculopathy of diabetic mice, retinal acellular capillary, the expression of tight junction proteins, and blood-retinal barrier destruction was observed. Finally, we validated the GPX4 as the target of porous Se@SiO2 nanospheres via decreased expression of GPX4 and detected the level of MDA, GSH/GSSG, TNF-α, IFN-γ, IL -1ß, wound healing assay, and tube formation in high glucose (HG) cultured Human retinal microvascular endothelial cells (HRMECs). RESULTS: The porous Se@SiO2 nanospheres reduced the level of MDA, TNF-α, IFN-γ, and IL -1ß, while increasing the level of GPX4 and GSH/GSSG in diabetic mice. Therefore, porous Se@SiO2 nanospheres reduced the number of retinal acellular capillaries, depletion of tight junction proteins, and vascular leakage in diabetic mice. Further, we identified GPX4 as the target of porous Se@SiO2 nanospheres as GPX4 inhibition reduced the repression effect of anti-lipid peroxidation, anti-inflammatory, and protective effects of endothelial cell dysfunction of porous Se@SiO2 nanospheres in HG-cultured HRMECs. CONCLUSION: Porous Se@SiO2 nanospheres effectively attenuated retinal vasculopathy in diabetic mice via inhibiting excess lipid peroxidation and inflammation by target GPX4, suggesting their potential as therapeutic agents for DR.


Asunto(s)
Diabetes Mellitus Experimental , Retinopatía Diabética , Nanosferas , Selenio , Humanos , Ratones , Animales , Retinopatía Diabética/tratamiento farmacológico , Retinopatía Diabética/metabolismo , Selenio/metabolismo , Selenio/farmacología , Selenio/uso terapéutico , Dióxido de Silicio/metabolismo , Dióxido de Silicio/farmacología , Dióxido de Silicio/uso terapéutico , Diabetes Mellitus Experimental/metabolismo , Células Endoteliales/metabolismo , Peroxidación de Lípido , Porosidad , Factor de Necrosis Tumoral alfa/metabolismo , Disulfuro de Glutatión/metabolismo , Disulfuro de Glutatión/farmacología , Disulfuro de Glutatión/uso terapéutico , Inflamación/metabolismo , Antiinflamatorios/uso terapéutico , Proteínas de Uniones Estrechas/metabolismo
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