Formation Of Nanopores Research Articles

Quantifying the Anomalous Local and Nanostructure Evolutions Induced by Lattice Oxygen Redox in Lithium-Rich Cathodes.

Due to their accessible lattice oxygen redox (l-OR) at high voltages, Li-rich layered transition metal (TM) oxides have shown promising potential as candidate cathodes for high-energy-density Li-ion batteries. However, this l-OR process is also associated with unusual electrochemical issues such as voltage hysteresis and long-term voltage decay. The structure response mechanism to the l-OR behavior also remains unclear, hindering rational structure optimizations that would enable practical Li-rich cathodes. Here, this study reveals a strong coupling between l-OR and structure dynamic evolutions, as well as their effects on the electrochemical properties. Using the technique of neutron total scattering with pair distribution function analysis and small-angle neutron scattering, this study quantifies the local TM migration and formation of nanopores that accompany the l-OR. These experiments demonstrate the causal relationships among l-OR, the local/nanostructure evolutions, and the unusual electrochemistry. The TM migration triggered by the l-OR can change local oxygen coordination environments, which results in voltage hysteresis. Coupled with formed oxygen vacancies, it will accelerate the formation of nanopores, inducing a phase transition, and leading to irreversible capacity and long-cycling voltage fade.

(Europe Section Heinz Gerischer Award) The Long Reach of Electrochemistry: Semiconductors, Metallization and Energy Storage

Research in several different areas over the past half-century is briefly reviewed with some discussion on the evolution of equipment and techniques. Examples from our work on oxygen evolution on ruthenium and iridium and electrochromism in anodic iridium oxides in the 1970s and on lithium batteries in the 1980s are discussed. Topics in the science and technology of compound semiconductors range from epitaxial crystal growth to electrochemistry and nanopore formation. Some results are presented on electrodeposition of copper metallization including in-situ stress measurements and atomic force microscopy during deposition, and spontaneous morphology changes during room-temperature aging. Electrochemical kinetics of vanadium redox reactions on carbon electrodes is discussed as well as state-of-charge monitoring and thermal stability of the positive electrode in vanadium flow batteries.

Single-molecule tracking of perfringolysin O assembly and membrane insertion uncoupling.

We exploit single-molecule tracking and optical single channel recording in droplet interface bilayers to resolve the assembly pathway and pore formation of the archetypical cholesterol-dependent cytolysin nanopore, Perfringolysin O. We follow the stoichiometry and diffusion of Perfringolysin O complexes during assembly with 60 ms temporal resolution and 20 nm spatial precision. Our results suggest individual nascent complexes can insert into the lipid membrane where they continue active assembly. Overall, these data support a model of stepwise irreversible assembly dominated by monomer addition, but with infrequent assembly from larger partial complexes.

Role of interfacial hydrophobicity in antimicrobial peptide magainin 2-induced nanopore formation

Antimicrobial peptide magainin 2 (Mag) forms nanopores in lipid bilayers and induces membrane permeation of the internal contents from vesicles. The binding of Mag to the membrane interface of a giant unilamellar vesicle (GUV) increases its fractional area change, δ, which is one of the main causes of Mag-induced nanopore formation. However, the role of its amino acid composition in the Mag-induced area increase and the following nanopore formation is not well understood. Here, to elucidate it we examined the role of interfacial hydrophobicity of Mag in its nanopore formation activity by investigating de novo-designed Mag mutants-induced nanopore formation in GUVs. Aligned amino acid residues in the α-helix of Mag were replaced to create 3 mutants: F5A-Mag, A9F-Mag, and F5,12,16A-Mag. These mutants have different interfacial hydrophobicity due to the variation of the numbers of Phe and Ala because the interfacial hydrophobicity of Phe is higher than that of Ala. The rate constant of Mag mutant-induced nanopore formation, kp, increased with increasing numbers of Phe residues at the same peptide concentration. Further, the Mag mutant-induced δ increased with increasing numbers of Phe residues at the same peptide concentration. These results indicate that kp and δ increase with increasing interfacial hydrophobicity of Mag mutants. The relationship between kp and δ in the Mag and its mutants clearly indicates that kp increases with increasing δ, irrespective of the difference in mutants. Based on these results, we can conclude that the interfacial hydrophobicity of Mag plays an important role in its nanopore formation activity.

Ultrafine nanoporous intermetallic catalysts by high-temperature liquid metal dealloying for electrochemical hydrogen production

Intermetallic compounds formed from non-precious transition metals are promising cost-effective and robust catalysts for electrochemical hydrogen production. However, the development of monolithic nanoporous intermetallics, with ample active sites and sufficient electrocatalytic activity, remains a challenge. Here we report the fabrication of nanoporous Co7Mo6 and Fe7Mo6 intermetallic compounds via liquid metal dealloying. Along with the development of three-dimensional bicontinuous open porosity, high-temperature dealloying overcomes the kinetic energy barrier, enabling the direct formation of chemically ordered intermetallic phases. Unprecedented small characteristic lengths are observed for the nanoporous intermetallic compounds, resulting from an intermetallic effect whereby the chemical ordering during nanopore formation lowers surface diffusivity and significantly suppresses the thermal coarsening of dealloyed nanostructure. The resulting ultrafine nanoporous Co7Mo6 exhibits high catalytic activity and durability in electrochemical hydrogen evolution reactions. This study sheds light on the previously unexplored intermetallic effect in dealloying and facilitates the development of advanced intermetallic catalysts for energy applications.

Spontaneous formation of nanopores within a nanofilm: Phase diagram and multiple stable states

Spontaneous formation of a nanopore within a liquid nanofilm immersed in a solvent was explored by many-body dissipative particle dynamics simulations. The nanofilm is sandwiched between two plates with circular orifices. As the liquid amount in the nanofilm changes, the menisci of the nanofilm near the orifices will be altered accordingly. The state of the nanofilm depicted by the mean curvature (H) of the meniscus depends on the apparent density (ρa) of the film and four regimes can be identified: (I) bulged film, (II) symmetric indented film, (III) asymmetric indented film, and (IV) nanopore formation. In the former two regimes, two identical convex (I) or concave (II) menisci are formed near the orifices. As ρa decreases further, the concave menisci are different on both sides of the nanofilm (III), and eventually the axis-symmetric nanopores (IV) emerge spontaneously. The relationship between H and ρa is not monotonous and involves minimum, maximum, and plain. As a result, multiple stable states are observed at the same Laplace pressure (ΔP) which relates to the mean curvature by the Young-Laplace equation. At a specific ΔP, the nanopore develops at lower ρa, while the indented film appears at higher ρa.

Fresh or aged: Short time anodization of titanium to understand the influence of electrolyte aging on titania nanopores

Electrochemical anodization (EA) is a simple and cost-effective technique to fabricate controlled nanostructures on Ti substrates, such as TiO2 nanotubes and nanopores. Electrolyte aging of organic EA electrolytes (repeated EA using non-target Ti before EA of target Ti) is recognized to influence the characteristics of the anodized nanostructures. However, there is limited information about how surface topography and electrolyte aging dictate the formation and characteristics of the anodized nanostructures. In the current study, short-time EA (starting at 10 s) of micro-machined Ti substrates was performed with electrolytes of various ages (fresh/unused, 15 h aged and 30 h aged), followed by evaluation of the TiO2 nanopores (TNPs) characteristics in terms of topography, chemistry, stability and protein adhesion. The results showed that aligned TNPs were obtained earlier (120 s) with fresh electrolyte as compared to the aged electrolyte EA (600 s). Interestingly, TNPs fabricated using fresh electrolyte (at lower EA times) showed favorable wettability, protein adhesion capacity and mechanical properties compared with aged electrolyte counterparts. The findings of the study demonstrate how nanopore formation differs between fresh and aged electrolytes when performing EA of micro-machined Ti, which provides an improved understanding of electrolyte aging and its influence on anodized nanostructures.

Bulk diffusion regulated nanopore formation during vapor phase dealloying of a Zn-Cu alloy

Dealloying is a robust method for fabricating 3D bicontinuous porous materials with open porosity and large specific surface areas. The formation of nanopores usually results from two kinetically competing processes at dealloying fronts: desertion of sacrificed elements and self-assembly of lingered elements by diffusion. Since surface and interface diffusivities are usually much higher than bulk, dealloying is typically fulfilled by the fast processes while the slow bulk alloy diffusion in precursor alloys is not commonly involved into the formation of open porosity during a dealloying process. Here we report that open pore formation in a Cu12Zn88 alloy is regulated by the bulk alloy diffusion during high-temperature vapor phase dealloying. The growth of dealloyed porous microstructure is facilitated by the formation of an up-front γ-Cu34Zn66 intermediate phase and, thereby, the dealloying kinetics is mediated by the evolution of the solid intermediate phase through bulk diffusion. The two-step dealloying process may pave a new way to tailor porous microstructure by designing and controlling intermediate phase formation.

Localized Nanopore Fabrication via Controlled Breakdown.

Nanopore sensors provide a unique platform to detect individual nucleic acids, proteins, and other biomolecules without the need for fluorescent labeling or chemical modifications. Solid-state nanopores offer the potential to integrate nanopore sensing with other technologies such as field-effect transistors (FETs), optics, plasmonics, and microfluidics, thereby attracting attention to the development of commercial instruments for diagnostics and healthcare applications. Stable nanopores with ideal dimensions are particularly critical for nanopore sensors to be integrated into other sensing devices and provide a high signal-to-noise ratio. Nanopore fabrication, although having benefited largely from the development of sophisticated nanofabrication techniques, remains a challenge in terms of cost, time consumption and accessibility. One of the latest developed methods—controlled breakdown (CBD)—has made the nanopore technique broadly accessible, boosting the use of nanopore sensing in both fundamental research and biomedical applications. Many works have been developed to improve the efficiency and robustness of pore formation by CBD. However, nanopores formed by traditional CBD are randomly positioned in the membrane. To expand nanopore sensing to a wider biomedical application, controlling the localization of nanopores formed by CBD is essential. This article reviews the recent strategies to control the location of nanopores formed by CBD. We discuss the fundamental mechanism and the efforts of different approaches to confine the region of nanopore formation.

Alterations of Carbonate Mineral Matrix and Kerogen Micro-Structure in Domanik Organic-Rich Shale during Anhydrous Pyrolysis

The study of organic-rich carbonate-containing shales after heating is an important task for the effective application of in-situ thermal kerogen conversion technologies implemented for these types of rocks. This research was conducted to study changes in the rocks of the Domanik Formation after high-temperature treatment, taking into account the nature of structural changes at the micro level and chemical transformations in minerals. The sample of organic-rich carbonate-containing shales of the Domanik Formation was treated in stages in a pyrolizer in an inert atmosphere in the temperature range of 350–800 °C for 30 min at each temperature. By means of X-ray powder diffractometry (XRPD), HAWK pyrolysis, light and scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and computed micro-tomography, the characteristics of the rock before and after each heating stage were studied. The results showed significant alteration of the mineral matrix in the temperature range 600–800 °C, including the decomposition of minerals with the formation of new components, and structural alterations such as fracturing micropore formation. The organic matter (OM) was compacted at T = 350–400 °C and fractured. The evolution of void space includes fracture formation at the edges between rock components, both in organic matter and in minerals, as well as nanopore formation inside the carbonate mineral matrix. The results obtained show what processes at the microlevel can occur in carbonate-containing organic-rich shales under high-temperature treatment, and how these processes affect changes in the microstructure and pore space in the sample. These results are essential for modeling and the effective application of thermal EOR in organic-rich shales.

(Digital Presentation) Advances in Cryo-Atom Probe Tomography Studies on Formation of Nanoporous Metals By Dealloying

The selective removal of a less noble (more chemically active) metal from a mixture of 2–3 metals can yield a bicontinuous, open-pore, 3D nanoporous metal (NPM), that is rich in the more noble metal(s)1. NPMs have been successfully developed by the intelligent use of the conventionally-undesired dealloying corrosion. The excellent properties of NPMs are attributed to the surface area-to-volume ratio, and high curvature of nanoligament surfaces 2,3 . Experimental work on NPMs revealed the formation of uniformly nanoporous structure by dealloying AgAu alloy in nitric acid, a method still widely used until today for making nanoporous gold (NPG). This dealloying process is complex: the selective dissolution of the less-noble element should lead to the creation of surface vacancies or adatoms, which migrate across the surface to form surface roughening features, and thus assisting the migration of the residual more-noble atoms, leading to island growth4.Ex-situ characterization cannot fully explain some intricate details at the dealloying interface and at the surface of the formed nanoligaments. Gaining insight into initial stages of dealloying, and the inherent competition between surface roughening from the dissolution of silver atoms, and surface smoothening from surface diffusion of gold atoms5, can only be done effectively by monitoring the changes occurring at the surfaces of alloys in-situ. Several notable in-situ methods were used to characterize formation of NPMs, such as TEM 6, often limited by the 2D nature of the analysis. Also, synchrotron-based methods such as X-ray nanotomography 7 and neutron scattering 8 were limited by resolution and lack of compositional contrast. APT is a powerful technique that provides 3D characterization9 and near-atomic-scale compositional analysis of materials, and could complement the abovementioned suite of techniques, yet the analysis of nanoporous structure comes with challenges.Aiming to develop a universal method for probing corrosion systems by APT, the concept of embedding frozen solutions in corroded systems was developed and reported in a recent reporting 10 of analyzing NPMs along with frozen water-based solutions. This involved the joint use of an ensemble of equipment and techniques that connect the frozen liquid to the atom probe, including a plasma-focused ion beam (PFIB) where the preparation of APT specimens uses a cryostage, and transfer of the frozen sample through ultra-high-vacuum suitcase11. This paved the way for many advances in characterization of corrosion processes, as the possibility of freezing corrosion reactions for APT (now known as cryo-APT) arises. Here, we further develop cryo-APT to probe into the mechanisms of dealloying in AgAu and how that leads to the formation of NPG using our in-situ approach. Nanoligament structure will be correlated with dealloying conditions by making observations at the solid-liquid interface in 3D. References Newman, R. C. 2.05 - Dealloying. in Shreir’s Corrosion (eds. Cottis, B. et al.) 801–809 (Elsevier, 2010).Zielasek, V. et al. Gold Catalysts: Nanoporous Gold Foams. Angew. Chemie Int. Ed. 45, 8241–8244 (2006).Xue, Y., Markmann, J., Duan, H., Weissmüller, J. & Huber, P. Switchable imbibition in nanoporous gold. Nat. Commun. 5, (2014).Forty, A. J. & Rowlands, G. A possible model for corrosion pitting and tunneling in noble-metal alloys. Philos. Mag. A Phys. Condens. Matter, Struct. Defects Mech. Prop. (1981) doi:10.1080/01418618108239399.Erlebacher, J., Newman, C. & Sieradzki, K. Fundamental physics and chemistry of nanoporosity evolution during dealloying. RSC Nanosci. Nanotechnol. 11–29 (2012) doi:10.1039/9781849735285-00011.Liu, P. et al. Dealloying Kinetics of AgAu Nanoparticles by In Situ Liquid-Cell Scanning Transmission Electron Microscopy. Nano Lett. 20, 1944–1951 (2020).Chen-Wiegart, Y. C. K. et al. In situ imaging of dealloying during nanoporous gold formation by transmission X-ray microscopy. Acta Mater. 61, 1118–1125 (2013).Corcoran, S. G., Wiesler, D. G. & Sieradzki, K. An in Situ Small Angle Neutron Scattering Investigation of Ag0.7Au0.3 Dealloying Under Potential Control. MRS Proc. 451, 93 (1996).Gault, B., Moody, M. P., Cairney, J. M. & Ringer, imon P. Atom Probe Microscopy. vol. 160 (Springer New York, 2012).El-Zoka, A. A. et al. Enabling near-atomic–scale analysis of frozen water. Sci. Adv. 6, eabd6324 (2020).Stephenson, L. T. et al. The LaplacE project: An integrated suite for preparing and transferring atom probe samples under cryogenic and UHV conditions. PLoS One (2018) doi:10.1371/journal.pone.0209211. Figure 1

Porous gold nanomesh films electrodeposited in toluene-based dynamic soft template

Two-dimensional (2D) metallic nanomaterials have received much attention as next-generation materials. The creation of the characteristic pores into 2D metallic materials is expected to improve performance in sensing, surface-enhanced Raman spectroscopy, electrocatalytic activity, and so on. Here, we report that gold electrodeposition in a toluene-based bicontinuous microemulsion (BME), called a dynamic soft template, provides porous gold nanomesh (PGNM) film. The selective toluene adsorption onto Au{111} surfaces induces anisotropic 2D growth of gold in the aqueous phase of BME, and an intertwined network of water and toluene nanochannels in BME resulted in the formation of abundant in-plane nanopores. Toluene adsorption during Au electrodeposition makes the {111}-oriented Au surfaces more lipophilic, i.e., a structural change in BME is induced to expose the organic phase solution selectively to the toluene-adsorbed {111} Au surfaces. This dynamic change in the BME solution structure during electrodeposition might enhance the anisotropic growth of gold (dynamic soft templating). Electrochemical behaviors of low-index planes of Au electrode supported the growth mechanism of PGNM film.

Effect of Metal-Precursor Stacking Order on Volume-Defect Formation in CZTSSe Thin Film: Formation Mechanism of Blisters and Nanopores.

In this study, we investigated the effect of the stacking order of metal precursors on the formation of volume defects, such as blisters and nanopores, in CZTSSe thin-film solar cells. We fabricated CZTSSe thin films using three types of metal-precursor combinations, namely, Zn/Cu/Sn/Mo, Cu/Zn/Sn/Mo, and Sn/Cu/Zn/Mo, and studied the blister formation. The blister-formation mechanism was based on the delamination model, taking into consideration the compressive stress and adhesion properties. A compressive stress could be induced during the preferential formation of a ZnSSe shell. Under this stress, the adhesion between the ZnSSe film and the Mo substrate could be maintained by the surface tension of a metallic liquid phase with good wettability, or by the functioning of ZnSSe pillars as anchors, depending on the type of metal precursor used. Additionally, the nanopore formation near the back-contact side was found to be induced by the columnar microstructure of the metal precursor with the Cu/Zn/Mo stacking order and its dezincification. Based on the two volume-defect-formation mechanisms proposed herein, further development of volume-defect-formation suppression technology is expected to be made.

Anodic growth and pre-calcification on β-Ti-40Nb alloy: Effects on elastic modulus, electrochemical properties, and bioactivity

This study evaluated the surface optimization of β-Ti-40Nb alloy in terms of corrosion and bioactivity properties. Electrochemical anodization at different voltages was used to synthesize (Ti,Nb)O2 nanostructures (nanopores (NPs)) and (nanotubes (NTs)) on samples' surfaces, allowing the analysis of their influence on performances related to those properties. Then, (Ti,Nb)O2 NPs and NTs were annealed at 550 °C to crystallize the previously obtained amorphous (Ti,Nb)O2 into a mixture of anatase and rutile. Also, a pre-calcification process (PC) was applied on annealed (Ti,Nb)O2 NPs and NTs. SEM micrographs showed the presence of NTs (10 V) and NPs (20 V) after anodization. After annealing, the morphology of (Ti,Nb)O2 NPs and NTs remained constant for both diameter and length. XRD analysis confirmed that as-anodized amorphous (Ti,Nb)O2 was crystallized, after annealing, into a mixture of anatase-rutile phases. Corrosion properties were evaluated through the open circuit potential (OCP), potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS). Samples were immersed in a simulated body fluid (SBF) solution for one to 14 days to assess the bioactivity. The bioactivity evaluation was carried out by mass gain. Also, the amount of apatite precipitated on the sample's surface was determined through SEM-EDS. The results showed that PC samples presented similar corrosion properties compared to the annealed samples. However, PC processing improved the bioactivity (apatite formation) of (Ti,Nb)O2 NTs and NPs modified β-Ti-40Nb alloy.

Multiscale physical–chemical analysis of the impact of fracture networks on weathering: Application to nickel redistribution in the formation of Ni-laterite ores, New Caledonia

Supergene processes related to downward water migration and dissolution of primary minerals in the New Caledonian peridotites result in Ni enrichment at the bottom of the lateritic profile near bedrock. However, the combined effects of relief, lateral fluid flow, and complex inherited discontinuity networks filled by serpentine generate a more complex Ni distribution than a simple flat horizon. In surficial environments, fluid flow and mass transfer are not limited to the vertical scale; they can also be related to lateral fluid circulation and local drainage along damage zones in the vicinity of faults. In this study, we present new structural, petrophysical and geochemical data for core samples to shed light on the impact of a fracture network on the alteration and progression of the Ni-enrichment front during weathering. The analysis of element redistribution by XRF mapping coupled with fracture extraction from computed tomography (CT) establishes that the serpentine fracture network comprises sets of sub-orthogonal fractures whose orientations are potentially determined by pre-existing magmatic foliation. The progression of the olivine dissolution front leads to the redistribution and concentration of Ni into the serpentine fracture network as secondary Mg-Ni talc-like phases. The increase in porosity from < 1 % in the bedrock to > 10 % in the saprock is mainly driven by the formation of nanopores. Nanoporosity may control the development of the weathering front and the redistribution of Ni by small-scale diffusion. Structural and geochemical characteristics identified at the sample scale are analogous to those observed on the larger scale of the outcrop and deposit. Scale invariance in the structural organization and geochemical evolution indicates the potential upscaling of the processes involved in the redistribution of Ni.

Shale’s Pore Structure and Sorption-Diffusion Characteristics: Effect of Analyzing Methods and Particle Size

The delineation of pore size and surface area distribution and methane sorption-diffusion capacity in gas shale reservoirs is crucial for the estimation of storage capacity, anticipating flow characteristics, and field development. A systematic approach and guidelines are needed for the analysis of the pore size and surface area distribution of shale formations. The effect of shale sample size on the gas sorption and diffusion properties is not well understood either. The low-pressure nitrogen adsorption technique is a prevalent method for pore characterization of nanoporous shale formations. Although researchers adopted some corrections to the classical method for the analysis of pore size and surface area distribution, there is a significant mismatch between different approaches in depicting fine mesopore size and surface area (2–10 nm). In this study, the classical methods and density functional theory are employed to comparatively analyze the pore characteristics of some shale and clay samples for their applicability, efficacy, and consistency issues. Furthermore, the effect of shale particle size on the methane sorption capacity and diffusion is being investigated. It seems that confinement stress has less of a considerable effect on methane sorption (6% decrease). However, crushing shale rocks into smaller particles can significantly overestimate the methane adsorption capacity. The methane diffusion coefficient also increases with increasing the shale particle size by more than an order of magnitude.

Sacrificial Silver Recovery during Nanoporous Gold Formation by Electrolytic Dealloying of Gold-Silver Alloy

Electrolytic dealloying has proven to be a practical technique for fabricating nanoporous metals such as nanoporous Au (NP-Au). This widely studied material has novel properties that are useful in applications ranging from chemical sensing to energy storage. Building off the success of this field, issues concerning the sustainability of fabricating NP-Au through dealloying need to be further explored, such as the large amount of valuable sacrificial Ag material dissolved in solution after dealloying is complete. In this work, an electrolytic cell is created consisting of a Au–Ag alloy foil working electrode and a Ag foil counter and reference electrode immersed in a non-aqueous Ag+ ion electrolyte. When a small overpotential is applied, the working electrode is dealloyed to form NP-Au. Unique to this configuration, Ag removed from the working electrode is simultaneously plated on the counter electrode, resulting in high yield recovery of Ag sacrificial material, which can be used to create new Au–Ag parent alloys. This integrated process of simultaneous dealloying and recovery of the sacrificial material significantly improves the sustainability and economic viability of dealloying. From these results, a generalized electrolytic dealloying fabrication procedure is derived that can be extended to a wide range of nanoporous metals.

Nanosecond Pulsed Electric Field (nsPEF): Opening the Biotechnological Pandora's Box.

Nanosecond Pulsed Electric Field (nsPEF) is an electrostimulation technique first developed in 1995; nsPEF requires the delivery of a series of pulses of high electric fields in the order of nanoseconds into biological tissues or cells. They primary effects in cells is the formation of membrane nanopores and the activation of ionic channels, leading to an incremental increase in cytoplasmic Ca concentration, which triggers a signaling cascade producing a variety of effects: from apoptosis up to cell differentiation and proliferation. Further, nsPEF may affect organelles, making nsPEF a unique tool to manipulate and study cells. This technique is exploited in a broad spectrum of applications, such as: sterilization in the food industry, seed germination, anti-parasitic effects, wound healing, increased immune response, activation of neurons and myocites, cell proliferation, cellular phenotype manipulation, modulation of gene expression, and as a novel cancer treatment. This review thoroughly explores both nsPEF’s history and applications, with emphasis on the cellular effects from a biophysics perspective, highlighting the role of ionic channels as a mechanistic driver of the increase in cytoplasmic Ca concentration.

Poroptosis: A form of cell death depending on plasma membrane nanopores formation

SummaryImmunogenic cell death (ICD) in malignant cells can decrease tumor burden and activate antitumor immune response to obtain lasting antitumor immunity, leading to the elimination of distant metastases and prevention of recurrence. Here, we reveal that ppM1 peptide is capable of forming irreparable transmembrane pores on tumor cell membrane, leading to ICD which we name poroptosis. Poroptosis is directly dependent on cell membrane nanopores regardless of the upstream signaling of cell death. ppM1-induced poroptosis was characterized by the sustained release of intracellular LDH. This unique feature is distinct from other well-characterized types of acute necrosis induced by freezing-thawing (F/T) and detergents, which leads to the burst release of intracellular LDH. Our results suggested that steady transmembrane-nanopore-mediated subacute cell death played a vital role in subsequent activated immunity that transforms to an antitumor immune microenvironment. Selectively generating poroptosis in cancer cell could be a promise strategy for cancer therapy.

Tailoring nanoporous graphene via machine learning: Predicting probabilities and formation times of arbitrary nanopore shapes.

Nanopores in graphene, a 2D material, are currently being explored for various applications, such as gas separation, water desalination, and DNA sequencing. The shapes and sizes of nanopores play a major role in determining the performance of devices made out of graphene. However, given an arbitrary nanopore shape, anticipating its creation probability and formation time is a challenging inverse problem, solving which could help develop theoretical models for nanoporous graphene and guide experiments in tailoring pore sizes/shapes. In this work, we develop a machine learning framework to predict these target variables, i.e., formation probabilities and times, based on data generated using kinetic Monte Carlo simulations and chemical graph theory. Thereby, we enable the rapid quantification of the ease of formation of a given nanopore shape in graphene via silicon-catalyzed electron-beam etching and provide an experimental handle to realize it, in practice. We use structural features such as the number of carbon atoms removed, the number of edge atoms, the diameter of the nanopore, and its shape factor, which can be readily extracted from the nanopore shape. We show that the trained models can accurately predict nanopore probabilities and formation times with R2 values on the test set of 0.97 and 0.95, respectively. Not only that, we obtain physical insight into the working of the model and discuss the role played by the various structural features in modulating nanopore formation. Overall, our work provides a solid foundation for experimental studies to manipulate nanopore sizes/shapes and for theoretical studies to consider realistic structures of nanopores in graphene.