Determining the association between mitochondrial DNA methylation and transcription

Unlike DNA methylation in nuclear DNA, which has been extensively studied, mitochondrial DNA methylation is still at a preliminary stage of research. Moreover, the relationship between mitochondrial DNA methylation and the expression of mitochondrial genes has not yet been thoroughly explored. This study investigates mitochondrial DNA methylation and its impact on gene expression in adult chickens (Gallus gallus) subjected to developmental hypoxia, hypothermia, and combined treatments. Using quantitative PCR, we analyzed mitochondrial copy number and gene expression, while Oxford Nanopore sequencing was used to assess DNA methylation levels. Results indicate that mitochondrial gene expression linked to the electron transport chain complex IV changes with treatment, prior to copy number normalization. However, methylation analysis revealed very low levels of mitochondrial DNA methylation, predominantly at CpG sites. Due to these minimal methylation levels, the relationship between DNA methylation and transcription in mitochondria could not be established. This research underscores the complexity of mitochondrial epigenetics and highlights its potential role in response to environmental stress, providing insights into the subtle yet detectable effects of mitochondrial DNA methylation on mitochondrial activity

Industrial-scale H2O2 electrosynthesis in practical electrochemical cell systems

Hydrogen peroxide generated from the electrochemical reaction with oxygen is particularly interesting due to its growing demand. Although most research has focused on highly active and stable electrocatalysts for H2O2 generation, substantial challenges still impede the industry–relevant scale application of producing liquid H2O2 solution via electrochemical methods. This review emphasizes the difficulties of making highly concentrated H2O2 products without other electrolyte impurities regarding the catalyst–electrolyte interface and reactor engineering. Furthermore, we discuss the possibility of direct in-situ consumption of H2O2 to other thermo-/electrochemical oxidation reactions even at low concentrations, even with salt ions. This approach allows the electrochemical route to become more competitive in the future. © 2023 Elsevier B.V.11Nsciescopu

Effect of Allium senescens Extract on Sorafenib Resistance in Hepatocarcinoma Cells

Although Allium species are involved in bioactivity, to the best of our knowledge, there is no research on the effects of Allium senescens on drug resistance in hepatocarcinoma. Ultra-high performance liquid chromatography was used to determine the concentration of several bioactive compounds in A. senescens extract; flow cytometry, reverse transcription–quantitative polymerase chain reaction, and siRNA-mediated knockdown to estimate the levels of different markers in HepG2 cells. The quantity of p-coumaric acid in the extract was 4.7291 ± 0.06 μg/mL, and the protein of relevant evolutionary and lymphoid interest (PRELI) in the resistant cells decreased 2.1 times in the presence of p-coumaric acid. The resistant cells strongly downregulated the efflux transporters (ABCB1, ABCC2, and ABCG2) when exposed to the extract or p-coumaric acid and when PRELI was knocked down, in contrast to the influx proteins (OCT-1). Additionally, the extract induced mitochondrial apoptosis and suppressed autophagy. Consequently, the extract and p-coumaric acid attenuated drug resistance of HepG2 cells through the downregulation of PRELI, a key protein associated with the modulation of drug transporter expression, the activation of autophagy, and mitochondrial apoptosis. Our results indicate that A. senescens extract is beneficial in protecting cancer cells against drug resistance and sustaining the efficacy of sorafenib against liver cancer

Recent progress in in situ/operando analysis tools for oxygen electrocatalysis

Fuel cell and water electrolyzer technology have been intensively investigated in the last decades toward sustainable and renewable energy conversion systems. For improved device performance and service life, nanostructured electrocatalysts on electrode have been extensively developed based on the principle of structure-activity-stability correlation. However, overall device efficiency is seriously hindered by sluggish oxygen electrocatalysis, including oxygen reduction reaction and oxygen evolution reaction. As a result, tremendous efforts have been made to construct the most active surfaces with robust durability. For knowledge-based approaches toward systematic development of highly functional nanostructures, fundamental principles within oxygen electrocatalysis should be uncovered including reaction intermediate, active site structures, and atomic dissolution from surface. However, conventional ex situ characterizations only provide a static picture of electrode surfaces without electrocatalysis. On the other hand, in situ/operando analyses allow us to directly monitor dynamics on electrode under operating conditions. In this review, we will introduce a set of in situ/operando analytical tools and summarize their contribution to fundamental researches on oxygen electrocatalysis. Taking both precious and non-precious electrocatalyst materials as examples, the most impending issues in oxygen electrocatalysis are covered with in situ/operando studies to highlight the power of in situ/operando techniques and encourage further efforts on advanced analytic techniques.11Nsciescopu

Carbon Shell on Active Nanocatalyst for Stable Electrocatalysis

© 2022 American Chemical Society.ConspectusElectrocatalysis is a key process for renewable energy conversion and fuel production in future energy systems. Various nanostructures have been investigated to optimize the electrocatalytic activity and realize efficient energy use. However, the long-term stability of electrocatalysts is also crucial for the sustainable and reliable operation of energy devices. Nanocatalysts are degraded by various processes during electrocatalysis, which causes critical performance loss. Recent operando analyses have revealed the mechanisms of electrocatalyst failure, and specific structures have been identified as robust against degradation. Nevertheless, achieving both high activity and robust stability with the same nanostructure is challenging because the structure-property relationships that affect activity and stability are different. The optimization of electrocatalysis is often limited by a large trade-off between activity and stability in catalyst structures. Therefore, it is essential to introduce functional structural units into catalyst design to achieve electrochemical stability while preserving high activity.In this Account, we highlight the strategic use of carbon shells on catalyst surfaces to improve the stability during electrocatalysis. For this purpose, we cover three issues in the use of carbon-shell-encapsulated nanoparticles (CSENPs) as robust and active electrocatalysts: the origin of the improved stability, the identification of active sites, and synthetic routes. Carbon shells can shield catalyst surfaces from both (electro)chemical oxidation and physical agglomeration. By limiting the exposure of the catalyst surface to an oxidizing (electro)chemical environment, carbon shells can preserve the initial active site structure during electrocatalysis. In addition, by providing a physical barrier between nanoparticles, carbon shells can maintain the high surface area of CSENPs by reducing particle agglomeration during electrocatalysis. This barrier effect is also useful for constructing more active or durable structures by annealing without surface area loss. Compared to the clear stabilizing effect, however, the effect of the shell on active sites on the CSENP surface can be puzzling. Even when they are covered by a carbon shell that can block molecular adsorption on active sites, CSENP catalysts remain active and even exhibit unique catalytic behavior. Thus, we briefly cover recent efforts to identify major active sites on CSENPs using molecular probes. Furthermore, considering the membranelike role of the carbon shell, we suggest several remaining issues that should be resolved to obtain a fundamental understanding of CSENP design. Finally, we describe two synthetic approaches for the successful carbon shell encapsulation of nanoparticles: two-step and one-step syntheses. Both the postmortem coating of nanocatalysts (two-step) and the in situ formation via precursor ligands (one step) are shown to produce a durable carbon layer on nanocatalysts in a controlled manner. The strengths and limitations of each approach are also presented to promote the further investigation of advanced synthesis methods.The hybrid structure of CSENPs, that is, the active catalyst surface and the durable carbon shell, provides an interesting opportunity in electrocatalysis. However, our understanding of CSENPs is still highly limited, and further investigation is needed to answer fundamental questions regarding both active site identification and the mechanisms of stability improvement. Only when we start to comprehend the fundamental mechanisms underlying electrocatalysis on CSENPs will electrocatalysts be further improved for sustainable long-term device operation.N

Carbon Shell on Active Nanocatalyst for Stable Electrocatalysis

© 2022 American Chemical Society. All rights reserved.ConspectusElectrocatalysis is a key process for renewable energy conversion and fuel production in future energy systems. Various nanostructures have been investigated to optimize the electrocatalytic activity and realize efficient energy use. However, the long-term stability of electrocatalysts is also crucial for the sustainable and reliable operation of energy devices. Nanocatalysts are degraded by various processes during electrocatalysis, which causes critical performance loss. Recent operando analyses have revealed the mechanisms of electrocatalyst failure, and specific structures have been identified as robust against degradation. Nevertheless, achieving both high activity and robust stability with the same nanostructure is challenging because the structure-property relationships that affect activity and stability are different. The optimization of electrocatalysis is often limited by a large trade-off between activity and stability in catalyst structures. Therefore, it is essential to introduce functional structural units into catalyst design to achieve electrochemical stability while preserving high activity.In this Account, we highlight the strategic use of carbon shells on catalyst surfaces to improve the stability during electrocatalysis. For this purpose, we cover three issues in the use of carbon-shell-encapsulated nanoparticles (CSENPs) as robust and active electrocatalysts: the origin of the improved stability, the identification of active sites, and synthetic routes. Carbon shells can shield catalyst surfaces from both (electro)chemical oxidation and physical agglomeration. By limiting the exposure of the catalyst surface to an oxidizing (electro)chemical environment, carbon shells can preserve the initial active site structure during electrocatalysis. In addition, by providing a physical barrier between nanoparticles, carbon shells can maintain the high surface area of CSENPs by reducing particle agglomeration during electrocatalysis. This barrier effect is also useful for constructing more active or durable structures by annealing without surface area loss. Compared to the clear stabilizing effect, however, the effect of the shell on active sites on the CSENP surface can be puzzling. Even when they are covered by a carbon shell that can block molecular adsorption on active sites, CSENP catalysts remain active and even exhibit unique catalytic behavior. Thus, we briefly cover recent efforts to identify major active sites on CSENPs using molecular probes. Furthermore, considering the membranelike role of the carbon shell, we suggest several remaining issues that should be resolved to obtain a fundamental understanding of CSENP design. Finally, we describe two synthetic approaches for the successful carbon shell encapsulation of nanoparticles: two-step and one-step syntheses. Both the postmortem coating of nanocatalysts (two-step) and the in situ formation via precursor ligands (one step) are shown to produce a durable carbon layer on nanocatalysts in a controlled manner. The strengths and limitations of each approach are also presented to promote the further investigation of advanced synthesis methods.The hybrid structure of CSENPs, that is, the active catalyst surface and the durable carbon shell, provides an interesting opportunity in electrocatalysis. However, our understanding of CSENPs is still highly limited, and further investigation is needed to answer fundamental questions regarding both active site identification and the mechanisms of stability improvement. Only when we start to comprehend the fundamental mechanisms underlying electrocatalysis on CSENPs will electrocatalysts be further improved for sustainable long-term device operation.11Nsciescopu

Maximizing the Active Site Densities of Single-Atomic Fe-N-C Electrocatalysts for High-Performance Anion Membrane Fuel Cells

Iron- and nitrogen-doped carbon (Fe-N-C) catalysts have received significant attention owing to their high oxygen reduction reaction (ORR) activities, which are comparable to those of state-of-the-art Pt/C catalysts. This high ORR activity originates from the atomically dispersed Fe coordinated with the nitrogen atom (Fe-N-x) active site. Increasing the Fe-N-x active site density can enhance the ORR activity. In this study, we suggest a facile and effective method for maximizing the active site densities using a simple ZnCl2 activation method. ZnCl2 activation was applied to the metal organic framework-derived Fe-N-C catalyst that exhibits superior ORR activity compared to Pt/C and a recently reported nonprecious metal catalyst. Through various electrochemical analyses, we confirmed that this activity originates from the effectively increased active site density. The anion-exchange membrane fuel cell (AEMFC) performance was measured to confirm practical applicability, and we obtained a significantly high performance of 1076 mA cm(-2) at 0.6 V, which is significantly higher than the currently reported performance of carbon-based Fe-N-C AEMFC cathode catalysts. We demonstrate the potential of our strategy for applications in various carbon-based materials that can be used for the development of high-efficiency electrochemical energy devices.11Nsciescopu

Dynamic Electrochemical Interfaces for Energy Conversion and Storage

Electrochemical energy conversion and storage are central to developing future renewable energy systems. For efficient energy utilization, both the performance and stability of electrochemical systems should be optimized in terms of the electrochemical interface. To achieve this goal, it is imperative to understand how a tailored electrode structure and electrolyte speciation can modify the electrochemical interface structure to improve its properties. However, most approaches describe the electrochemical interface in a static or frozen state. Although a simple static model has long been adopted to describe the electrochemical interface, atomic and molecular level pictures of the interface structure should be represented more dynamically to understand the key interactions. From this perspective, we highlight the importance of understanding the dynamics within an electrochemical interface in the process of designing highly functional and robust energy conversion and storage systems. For this purpose, we explore three unique classes of dynamic electrochemical interfaces: self-healing, active-site-hosted, and redox-mediated interfaces. These three cases of dynamic electrochemical interfaces focusing on active site regeneration collectively suggest that our understanding of electrochemical systems should not be limited to static models but instead expanded toward dynamic ones with close interactions between the electrode surface, dissolved active sites, soluble species, and reactants in the electrolyte. Only when we begin to comprehend the fundamentals of these dynamics through operando analyses can electrochemical conversion and storage systems be advanced to their full potential.ISSN:2691-370

Recent Advances in Electrochemical Oxygen Reduction to H2O2: Catalyst and Cell Design

Copyright © 2020 American Chemical Society. Electrochemical production of H2O2 from O2 is a promising alternative to the energy-intensive anthraquinone process that is currently used as an industry standard. Although most research on the oxygen reduction reaction (ORR) has focused on the 4-electron pathway to water relevant to fuel cells, the 2-electron ORR to produce H2O2 is also of significant commercial interest. The first half of this Perspective deals with the progress made in developing noble metal, carbon-based, and single-atom electrocatalysts and highlights the design strategies employed to obtain high selectivity toward H2O2. The second half addresses the challenges of large-scale production and how results obtained using a rotating ring disk electrode (RRDE) can be translated into commercially viable flow cells. This Perspective focuses on the design of catalysts and cells that will enable industrial-scale electrochemical H2O2 production.11sci