Probe Reaction Research Articles

Probing Surface Reactions on Multicomponent Glass Using Reflection-Absorption Infrared Spectroscopy.

The chemical reactivity of glass surfaces is often studied with elemental analysis techniques, and although such characterization methods provide insights on compositional changes from exposure to specific chemical conditions, molecule-specific chemical reactions are not determined unambiguously. This study demonstrates the use of reflection-absorption infrared spectroscopy (RAIRS) to detect molecular species on alkali-free boroaluminosilicate and alkali aluminosilicate glasses, using acetic acid vapor as a model reactant to probe reaction sites at the surface with or without pretreatment by aqueous solutions of varied pH. With the assistance of the theoretical calculation of spectral changes based on refractive indices of bulk materials, it was possible to identify the molecular species being removed and produced at the glass surface. It was found that acetic acid vapor reacts with the modifier ions present at the glass surface to form monodentate acetate groups. Such reactions caused the desorption of 2-2.5 monolayers of strongly bonded water that remained on the glass surface, even after exposure to vacuum for several hours. The overall reactivity of the glass surface with acetic acid was found to be relatively insensitive to the pH of the pretreatment solution, although the glass surface composition and network vibrations were impacted and varied with the pH of the solution.

Comparative economic analysis of batch vs. continuous manufacturing in catalytic heterogeneous processes: impact of catalyst activity maintenance and materials costs on total costs of manufacturing in the production of fine chemicals and pharmaceuticals

Abstract To evaluate the feasibility of transforming batch manufacturing processes in the fine chemicals and pharmaceutical industries to continuous synthesis, Capex, Opex and the total cost of manufacturing are estimated for production facilities for the hydrogenation of a nitro compound to its final amino counterpart. Two cases are evaluated: First, a high annual production dedicated plant, designed on the basis of processing 100,000 kg of the principal raw material per year, where raw materials cost, catalyst cost, and catalyst activity maintenance are varied over a broad range for typical industrial cases. Second, a “short campaign” model for a small volume production trial setup designed for the manufacture of only 100 kg of the final product, as a way to evaluate relevant industrial scenarios of scale-up and process development. A comparison is made between slurry batch, catalyst basket batch reactor and fixed bed continuous reactor manufacturing facilities. The hydrogenation of 2,4-dinitrotoluene was chosen as a probe reaction for the development of the manufacturing processes, with costs of the key raw material varying between $5 and $100 per kilogram, costs of catalyst varying between $100 and $1,500 per kilogram, and catalyst activity maintenances varying between 1,000 and 2,000,000 total turnovers before a change in catalyst load is necessary. For low catalyst activity maintenance, the total manufacturing costs for the fixed bed reactor process were always found to be higher than those of the two other alternatives. As catalyst activity maintenance increases, the manufacturing costs for the continuous alternative rapidly fall, reaching savings between 37 and 75% compared to the base batch reactor case, depending on the combination of costs of the key raw material and catalyst used. Graphical Abstract

High-precision chemical quantum sensing in flowing monodisperse microdroplets.

A method is presented for high-precision chemical detection that integrates quantum sensing with droplet microfluidics. Using nanodiamonds (ND) with fluorescent nitrogen-vacancy (NV) centers as quantum sensors, rapidly flowing microdroplets containing analyte molecules are analyzed. A noise-suppressed mode of optically detected magnetic resonance is enabled by pairing controllable flow with microwave control of NV electronic spins, to detect analyte-induced signals of a few hundredths of a percent of the ND fluorescence. Using this method, paramagnetic ions in droplets are detected with low limit-of-detection using small analyte volumes, with exceptional measurement stability over >103 s. In addition, these droplets are used as microconfinement chambers by co-encapsulating ND quantum sensors with various analytes such as single cells, suggesting wide-ranging applications including single-cell metabolomics and real-time intracellular measurements from bioreactors. Important advances are enabled by this work, including portable chemical testing devices, amplification-free chemical assays, and chemical imaging tools for probing reactions within microenvironments.

Supramolecular pre‐organisation rhodium and iridium metal complexes within M12L24 self‐assembled nanospheres for the confined synthesis Rh/Ir alloyed nanoparticles

Controlling the size and composition of metal nanoparticles is of considerable interest, as these are essential to their catalytic properties. We report the controlled synthesis Rh nanoparticles by preorganisation of metal complexes inside Pt12L24 nanospheres based on complementary hydrogen bonds before the reduction step that leads to nanoparticle formation. The encapsulated RhI complexes (Rh‐s @ G‐sphere) led to reasonable size control (2.8 ± 0.9 nm). We also report the formation of Rh‐Ir alloyed nanoparticles with varying Rh/Ir compositions. These heterometallic particles were evaluated in the hydrogenation of cinnamaldehyde (7) as a probe reaction. Besides a high activity in this probe reaction, the Rh particles also catalyzed the conversion of the solvent (CH3CN). The formed basic amine leads to follow‐up reactions of the product and compatibility issues with the hosting nanosphere. The solvent hydrogenation was effectively suppressed by using the Rh:Ir alloyed nanoparticles, provided that they contain >66% Ir. The Rh:Ir alloyed nanoparticles displayed high catalytic activity, reaching optimal selectivity and activity at an 8:16 ‐ Rh:Ir ratio. The combined catalytic results illustrate that pre‐organisation of the metal complexes in the nanosphere before the reduction with hydrogen effectively facilitates the formation of Rh:Ir alloyed nanoparticles.

Importance of the Cation-Water Interaction on Water Dissociation for Hydrogen Evolution

The solid-liquid interface models are generally concentrated on understanding either covalent interactions between adsorbates and solid surfaces or long-range liquid electrolyte–solid electrode electrostatic interactions. Recently, the focus of interfaces shifts to the cation-water interaction, which is not included in the conventionally pondered. This interaction reportedly plays a pivotal role in water-involved reactions because it affects the intramolecular O-H bond of water molecules. Herein, we demonstrate a correlation between the thermodynamics of water dissociation and the cation species using hydrogen evolution as a probing reaction. Surprisingly, a significantly improved onset potential of water reduction is observed by using multivalent cations, especially, the lowest solubility product (Ksp) towards metal hydroxide, Al3+. It infers that the metal cations interact directly or indirectly with water molecules to form the metal hydroxide, subsequently providing sufficient reactant, i.e., H+, at the electrode surface in the more positive potential region. By correlating electrochemical and spectroscopic results, we surmise that the presence of cations in weak acid conditions causes the formation of metal hydroxide compared to the absence of cations, resulting in a promoted onset potential of water reduction.

(Invited) Probing the Functionality of Lithium Carbonate in Lithium Metal Interphases through Model and Native SEI

The lithium (Li) metal anode promises significantly higher capacity than graphite and is central to strategies to develop advanced Li-ion batteries with improved energy, lifetime and performance. Yet, the Coulombic efficiency (CE) of Li anodes in liquid electrolytes still falls well below the >99.9% targeted for electric vehicles. Efficiency and capacity loss arise from uncontrolled reactivity at the solid electrolyte interphase (SEI) and its resulting physicochemical, ionic and electronic properties, which couple to inhomogeneous plating/stripping, SEI breakage, electrolyte infiltration and additional consumption, and ultimately to loss of active Li inventory as stranded Li0 or SEI Li+. Despite empirical insights into electrolyte design guidelines, quantitative understanding of SEI functionality is underdeveloped, hindering attempts to control and improve its properties through tailoring of its materials chemistry.This talk will discuss ongoing efforts to improve understanding of phase-specific functionality in the SEI, with an objective of identifying compositional design principles to minimize active Li inventory loss. We developed approaches to isolate and synthesize SEI-relevant ionic and organic phases, including lithium fluoride (LiF)1, lithium oxide (Li2O),2and recently lithium carbonate (Li2CO3), at representative nanometer-scale thicknesses directly on Li metal. These interfaces are interrogated via targeted electrochemical techniques to reveal their Li+ conductivity, providing a framework to assess which phases bolster, or hinder, ion transport in the SEI. Here we examine in detail the role of Li2CO3, a pervasive yet metastable SEI component that has long been asserted to improve CE in conventional carbonate electrolytes.3-5 By synthesizing model Li2CO3 interphases, we measure the ionic conductivity, probe reaction pathways in contact with specific electrolyte constituents, and interpret its properties against other key ionic SEI phases. We further examine the role of carbonate on the native SEI through re-examination of CO2 gas as a cell additive in a wider range of electrolytes—including modern formulations like ethers and localized high-concentration electrolytes (LHCEs)—than those studied previously. In combination with titration methods,6,7 we finally reveal how Li2CO3 relates to capacity loss at the anode and conditions in which enhancing Li2CO3 translates into improved CE. He, R. Guo, G. Hobold, H. Gao and B.M. Gallant, PNAS 2020, 117, 73-79.Guo and B.M. Gallant, Chemistry of Materials 2020, 32, 13, 5525-5533.Plichta, S. Slane, M. Uchiyama, M. Salomon, D. Chua, W. B. Ebner and H. W. Lin, J. Electrochem. Soc. 1989, 136, 1865. Aurbach, Y. Gofer, M. Ben-Zion and P. Aped, J. Electroanal. Chem 1992, 339, 451. D. Aurbach, I. Weissman, A. Zaban and O. Chusid, Electrochimica Acta 1994, 39, 51.Fang, J. Li, M. Zhang et al., Nature 2019,572, 511–515.M. Hobold and B. M. Gallant, ACS Energy Letters 2022, 7, 3458-3466.

Endogenous Telomerase-Activated Fluorescent Probes for Specific Detection and Imaging of Flap Endonuclease 1 in Cancer Cells and Tissues.

Flap endonuclease 1 (FEN1) is a structure-specific DNA repair enzyme that has emerged as a potential target for cancer diagnosis and treatment. However, existing FEN1 assays often suffer from complicated reaction schemes and laborious procedures, and only a few methods are available for the detection and imaging of FEN1 in living cells. Especially, FEN1 is not exclusive to cancer cells, but it is also shared by normal cells. Consequently, the specific detection of FEN1 in cancer cells remains a challenge. Herein, we develop a simple and selective fluorescent biosensor for the specific imaging of FEN1 in cancer cells and tissues by engineering a FEN1 detection probe with a telomerase-responsive unit. In the presence of telomerase, it induces an extension reaction and subsequent intramolecular reconfiguration of the detection probe, generating a suitable branched DNA structure for FEN1 recognition and facilitating the cleavage of the flap by FEN1 for the recovery of fluorescence signal. Because telomerase is undetectable in normal cells but highly upregulated in cancer cells, the detection probe can only be activated in cancer cells to generate a high signal. This assay is quite simple, with the requirement of merely a single probe for dual enzyme recognition and signal output. With the integration of the single-molecule counting technology, this biosensor can achieve a detection limit of 1.2 × 10-5 U/μL, and it can accurately detect FEN1 in living cells and clinical tissues, providing a new avenue for FEN1-associated fundamental research and clinical diagnosis.

Atmosphere-driven metal-support synergy in ZnO/Au catalysts for efficient piezo-catalytic hydrogen evolution

Piezo-catalysis, which leverages mechanical energy to drive chemical reactions, is emerging as a promising method for sustainable energy production. While the enhancement of piezo-catalytic performance through metal-support interactions is well-documented, the critical influence of the synthesis atmosphere during metal-loaded piezo-catalyst preparation has been a notable gap in the field. To this end, we systematically investigate how different atmospheric conditions during the synthesis of catalysts—without gas flow or with Ar, N2 and O2—affect metal dispersion, oxidation states, piezo-carrier dynamics, and electronic structure, and subsequently shape the metal-support interactions and piezo-catalytic activity. ZnO/Au, with Au deposited on ZnO, is selected as the model system, and hydrogen evolution reaction is used as the probe reaction. Our results demonstrate that an oxygen-enriched atmosphere significantly enhances the metal-support interactions, achieving an ultrahigh net hydrogen yield of 16.5 mmol·g–1·h–1 on ZnO/Au, a 3.58-fold increase over pristine ZnO. Specifically, the performance improvements substantially surpass those synthesized under other atmospheric conditions. Conversely, exposure to CO2 transforms the ZnO support into ZnCO3, adversely affecting its catalytic activity. These findings reveal the crucial impact of synthesis conditions on piezo-catalyst performance and thereby open new avenues for optimizing catalyst systems for enhanced sustainability.

Atomic Level Understanding of the Structural Stability and Catalytic Activity of Nanoporous Gold/Titania Cluster Inverse Catalysts at Ambient and High Temperatures.

Nanoporous gold (NPG) exhibits exceptional catalytic performance at low temperatures, but its activity declines at elevated temperatures due to structural coarsening. Loading metal oxide nanoparticles onto NPG can enhance its catalytic activity at high temperatures. In this work, we used NPG-supported titania nanoparticles as a model system (denoted as Ti2O4/NPG) to study their catalytic activity at ambient and high temperatures with CO oxidation as a probe reaction by density functional theory (DFT) calculation and ab initio molecular dynamics (AIMD) simulations. The possible factors that may affect the CO oxidation reaction pathways and energy profiles on the Ti2O4/NPG, such as oxygen vacancies; silver impurities; Mars-van Krevelen (MvK), Eley-Rideal (ER), or trimolecular Eley-Rideal (TER) mechanisms; and catalytic active sites, were comprehensively investigated. The results showed that reaction energy barriers on Ti2O4/NPG were not significantly decreased compared to the pristine NPG, indicating that their catalytic activities at ambient temperature were comparable. At the evaluated temperature (400 °C), the Ti2O4/NPG exhibited superior thermal stability and maintained its active sites, while the NPG reduced active sites due to surface coarsening. The strong oxide-metal interaction (SOMI) effect between the NPG and Ti2O4 nanoparticles is found to be a main factor for the high structural stability and catalytic activity at high temperatures.

Visualization of the Distance-Dependent Synergistic Interaction in Heterogeneous Dual-Site Catalysis.

Understanding the characteristics of interfacial hydroxyl (OH) at the solid/liquid electrochemical interface is crucial for deciphering synergistic catalysis. However, it remains challenging to elucidate the influences of spatial distance between interfacial OH and neighboring reactants on reaction kinetics at the atomic level. Herein, we visualize the distance-dependent synergistic interaction in heterogeneous dual-site catalysis by using ex-situ infrared nanospectroscopy and in situ infrared spectroscopy techniques. These spectroscopic techniques achieve direct identification of the spatial distribution of synergistic species and reveal that OH facilitates the reactant deprotonation process depending on site distances in dual-site catalysts. Via modulating Ir-Co pair distances, we find that the dynamic equilibrium between generation and consumption of OH accounts for high-efficiency synergism at the optimized distance of 7.9 Å. At farther or shorter distances, spatial inaccessibility and resistance of OH with intermediates lead to OH accumulation, thereby diminishing the synergistic effect. Hence, a volcano-shaped curve has been established between the spatial distance and mass activity using formic acid oxidation as the probe reaction. This notion could also be extended to oxophilic metals, like Ir-Ru pairs, where volcano curves and dynamic equilibrium further evidence the universal significance of spatial distances.

Substoichiometric La0.8MnO3-based nanocomposites for PGM-free activation of CH4: Ni or Cu? Surface or bulk?

Methane is a renewable fuel when derived from biogas upgrading or by CO2 capture and utilization, with the possibility of fully replacing natural gas in the already established gas infrastructure and engines. However, being a potent greenhouse gas, its use as fuel demands a sustainable activation procedure, to convert any residual traces of unburned CH4 into CO2, a challenging reaction especially at near-stoichiometric conditions typical of Three-Way Catalytic systems (TWC). To avoid expensive noble metals, we developed cheaper alternative catalysts: A-site deficient LaMnO3-based nanocomposites incorporating Ni and Cu. These elements were introduced either as B-site dopants in the perovskite lattice or deposited via Ammonia-driven Deposition-Precipitation (ADP) on the perovskite surface, in both cases yielding metal nanoparticles (NPs) after a reductive treatment. Characterization encompassed various techniques: XRD, N2 physisorption, SEM-EDX, XPS, H2-TPR, HAADF STEM-EDX. CH4 oxidation to CO2 under stoichiometric O2 served as the probe reaction, as model for TWC conditions in methane-fed engines. The LaMn-perovskite itself displayed a promising activity thanks to favourable morphological and redox features (50 % and 90 % CH4 conversion at 581 °C and 678 °C, respectively); further improvements could be obtained upon Ni and Cu loading. The best performances were achieved by: i) the catalyst prepared by Ni-ADP (50 % and 90 % CH4 conversion at 517 °C and 635 °C), featuring high Ni surface concentration and NPs density and a synergy with the perovskite support, as opposed to the low Ni surface concentration on B-site doped samples; ii) the reduced Cu-doped catalyst (50 % and 90 % CH4 conversion at 508 °C and 645 °C), thanks to the high activity of reduced Cu species, the low NPs size and good metal-support interaction, in contrast to the strong NPs agglomeration of the Cu-ADP catalyst. Among the two most active catalysts, a better long-term stability was retained by the Cu-doped sample. This work laid the foundation for the development of alternative CH4 oxidation catalysts at the stoichiometric air-to-fuel ratio, cheaper than commercial Pd-based ones.

Hydrophilicity Dependent Distribution of Water at Ionic Liquids/Metal Interface Monitored by Electrochemical SERS.

The understanding of the interfacial processes is critically important for extending the practical application of ionic liquids, particularly for the role of interfacial water. In the electrochemical system based on ionic liquid electrolytes, small amounts of water at the interface generate a significant change in the electrochemical behaviors of ionic liquids. Therefore, the investigation on the interfacial behavior of water is highly desired in ionic liquids with different anions, water content, and hydrophilicity. Herein, based on the probe strategy, in situ surface enhanced Raman spectroscopy (SERS) combined with electrochemical control (EC-SERS) was developed to investigate the influence of hydrophilicity/hydrophobicity of ionic liquids on the interfacial water. The water-sensitive transformation reaction of 4,4'-dimercaptoazobenzene (DMAB) to para-aminothiophenol (PATP) was employed as a probe reaction for investigating the behavior of interfacial water. The changes of relative SERS intensities of DMAB to PATP served as an indication of the quantity variation of interfacial water. The results show that the transformation reaction efficiencies were critically dependent on the additional water contents, potential, and hydrophilicity of ionic liquids. With a very low molar fraction of additional water (Xw = 0.01), transformation efficiency of DMAB (the amount of interfacial water) followed the sequence of [BMIm]BF4 < [BMIm]PF6 < [BMIm]Tf2N. It was in agreement with the hydrophobicity order of the ionic liquids. With the increase in additional water content, the potential for the full transformation was positively moved, and the efficiency increased significantly. The stronger hydrophobicity allowed more water molecules to migrate to the interface, which was attributed to the difference in interactions between water and the anions of ionic liquids. It demonstrated that the small amount of water tended to gather at the interface in hydrophobic ionic liquids. Compared to traditional cyclic voltammetry, the EC-SERS technique combined with probe reactions is more sensitive to interfacial water. It is anticipated to develop as a promising tool for the investigating water-related issues at interfaces and to provide guidance to screen ionic liquids for practical application.

Concentration and activation biresponsive strategy in one analysis system with simultaneous use of G4 structure-specific signal probe and enzyme-catalyzed reaction

BackgroundEnzymes with critical effects on life systems are regulated by expression and activation to modulate life processes. However, further insights into enzyme functions and mechanisms in various physiological processes are limited to concentration or activation analysis only. Currently, enzyme analysis has received notable attention, particularly simultaneous analysis of their concentration and activation in one system. Herein, N-methyl mesoporphyrin IX (NMM), a specific dye with notable structural selectivity for parallel G-quadruplex nucleic acid enzyme (G4h DNAzyme), is employed for the analysis of its concentration. In addition, the peroxidase activity of G4h DNAzyme is characterized based on G4h DNAzyme–catalyzed decomposition of H2O2 to continuously consume luminol. Accordingly, an increased fluorescence (FL) response of NMM and a decreased FL response of luminol could be simultaneously employed to analyze the concentration and activation of G4h DNAzyme. ResultHerein, a novel concentration and activation biresponsive strategy is proposed using a G4h DNAzyme–based model that simultaneously employs a G4h structure–specific signal probe for enzyme concentration analysis and G4h DNAzyme–catalyzed reactions for enzyme activation analysis. Under optimal conditions, the biresponsive strategy can be effectively used for the simultaneous analysis of G4h DNAzyme concentration and activation, with detection limits of 718.7 pM and 233.4 nM respectively, delivering acceptable performances both in cell and in vitro. SignificanceThis strategy can not only be applied to concentration and activation analyses of G4h DNAzyme but can also be easily extended to other enzymes by simultaneously combining concentration analysis via target-induced direct reaction and activation analysis via target-induced catalytic reaction, offering deeper insights into various enzymes and enabling their effective implementation in bioanalysis and biochemistry.

One-step synthesis of Pt@(CrMnFeCoNi)3O4 high entropy oxide catalysts through flame spray pyrolysis

High entropy oxides (HEOs) show great prospects in catalysis owing to their widely tunable component structures and ease of combination with active metals. However, the development of HEO catalysts is limited by the lack of efficient synthesis methods due to the difficulty of homogeneously mixing at least five elements. In this work, flame spray pyrolysis (FSP) is successfully employed to synthesize (CrMnFeCoNi)3O4 HEO with a single phase spinel structure in one step, which is verified by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS). Taking CO catalytic oxidation as a probe reaction, the Pt@(CrMnFeCoNi)3O4 HEO catalyst synthesized by FSP in one step is compared with the catalyst whose Pt is impregnated on (CrMnFeCoNi)3O4 HEO support. The FSP-made catalysts have a higher catalytic reaction rate and better redox ability, which lowers the temperature of complete CO conversion by nearly 100 °C. Furthermore, it can be observed that the flame parameters can be optimized to modify the particle size and oxygen vacancies of the HEO nanoparticles, thus enhancing the catalytic performances. This work demonstrates that FSP is an effective method for the one-step synthesis of HEO catalysts with excellent catalytic performance, providing a new perspective for the synthesis of HEO-based materials.

Clotrimazole Identified as a Selective UGT2B4 Inhibitor Using Canagliflozin-2'-O-Glucuronide Formation as a Selective UGT2B4 Probe Reaction.

UGT2B4 is a highly expressed drug-metabolizing enzyme in the liver contributing to the glucuronidation of several drugs. To enable quantitatively assessing UGT2B4 contribution toward metabolic clearance, a potent and selective UGT2B4 inhibitor that can be used for reaction phenotyping was sought. Initially, a canagliflozin-2'-O-glucuronyl transferase activity assay was developed in recombinant UGT2B4 and human liver microsomes (HLM) [±2% bovine serum albumin (BSA)]. Canagliflozin-2'-O-glucuronidation (C2OG) substrate concentration at half-maximal velocity value in recombinant UGT2B4 and HLM were similar. C2OG formation intrinsic clearance was five- to seven-fold higher in incubations containing 2% BSA, suggesting UGT2B4 susceptibility to the inhibitory unsaturated long-chain fatty acids released during the incubation. Monitoring for C2OG formation, 180 compounds were evaluated for UGT2B4 inhibition potency in the presence and absence of 2% BSA. Compounds that exhibited an apparent UGT2B4 IC50 of < 1 μM in HLM with 2% BSA were evaluated for inhibition of UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B7, UGT2B10, UGT2B15, and UGT2B17 catalytic activities to establish selectivity suitable for supporting UGT reaction phenotyping. In this study, clotrimazole was identified as a potent UGT2B4 inhibitor (HLM apparent IC50 of 11 to 35 nM ± 2% BSA). Moreover, clotrimazole exhibited selectivity for UGT2B4 inhibition (>24-fold) over the other UGT enzymes evaluated. Additionally, during this study it was discovered that the previously described UGT2B7 inhibitors 16α- and 16β-phenyllongifolol also inhibit UGT2B4. Clotrimazole, a potent and selective UGT2B4 inhibitor, will prove essential during UGT reaction phenotyping. SIGNIFICANCE STATEMENT: To mechanistically evaluate drug interactions, it is essential to understand the contribution of individual enzymes to the metabolic clearance of a drug. The present study describes the development of a UGT2B4 activity assay that enabled the discovery of the highly selective and potent UGT2B4 inhibitor clotrimazole. Clotrimazole can be used in UGT reaction phenotyping studies to estimate fractional contribution of UGT2B4.

Development of Metal-Oxide-Metal Micro-Well Array Biosensors for Highly Sensitive Detection of Covid-19

Biosensors play a crucial role in various fields, including medical diagnostics, environmental monitoring, and food safety. Enhancing the sensitivity of biosensors is essential for improving their performance and reliability. One effective approach to achieve this goal is by reducing the distance of electrodes, a parameter that significantly influences the sensor's response. Employing vertical structures to reduce electrode gaps offers several advantages. the heightened controllability of vertical structures facilitates easy adjustments to element size and shape, catering to specific application requirements and maximizing sensor performance. The choice of vertical structures presents a more accessible, flexible, and cost-effective solution from a manufacturing standpoint, particularly for large-scale sensor production.On the other hands, DNA testing plays a pivotal role in the context of COVID-19, demonstrating its profound significance in the identification, monitoring, and management of the virus. Through the analysis of genetic material, particularly RNA in the case of COVID-19, DNA testing enables accurate and timely diagnosis of infections. This precision is instrumental in differentiating the virus from other respiratory illnesses, facilitating early intervention and containment measures. Moreover, the genetic insights garnered from DNA testing contribute to a better understanding of the virus's behavior, mutations, and potential therapeutic targets, thereby informing public health strategies and vaccine development. The integration of DNA testing in the comprehensive approach to combating COVID-19 underscores its indispensable role in mitigating the impact of the pandemic on global health.In this study, we present the development of a novel biosensor based microwell array structure. The fabrication process employed a layer-by-layer method. To be brief, a 4-inch silicon wafer with a 300 nm thick thermal SiO2 was cleaned in acetone, isopropanol, and water. Subsequently, the bottom electrode was deposited by E-gun evaporator followed by a lift-off process. An extremely thin 45nm aluminum oxide layer was deposited by Atomic Layer Deposition (ALD). Then, a 100nm gold layer was deposited as the top electrode by E-gun. Finally, conclude the fabrication by defining the sensing area of the microwell array through Lithography and several etching steps.For the DNA immobilization process, the Covid-probe ssDNA was incubated with the biosensor at 4℃ within the PDMS wells overnight, followed by rinsed 3 times. And 1 uM Covid-target ssDNA was incubated after immobilization of probe DNA. The condition for the reaction of target and probe was 1 hour at room temperature, followed by rinsed 3 times in DI water.The detection was achieved using a combination of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), collectively offering a comprehensive approach for accurate and reliable measurements. The electrolyte consists of 1 mM KCl solution as supporting electrolytes and 5 mM ferricyanide/ferrocyanide as redox pair. The Rct charge transfer resistance of bare device is around 1320 Ohm due to the small sensing area of around 500 * 500 um2. After incubation with the probe DNA, the Rct is around 2150 Ohm indicating that the probe DNA binds to the Au surface successfully. Target DNA was quantitatively measured over a wide concentration range, spanning from 10 pM to 10 nM. The Rct variance from 2260 to 4970 Ohm.Our results demonstrate the biosensor's exceptional performance in terms of sensitivity and dynamic range, showcasing its potential application in the early and accurate diagnosis of Covid-19. The micro-well array biosensor, with its unique design and integrated electrochemical measurement strategy, holds promise for future advancements in point-of-care diagnostics and environmental monitoring. Figure 1

Rapid Detection of Methicillin Resistant Staphylococcus Aureus (MRSA) Using Electric-Double-Layer (EDL) Field-Effect Transistor (FET) Biosensors

According to the latest statistics and analysis by American researchers based on the data from 195 countries worldwide, it has been found that one person in every five people died due to sepsis. The annual death caused by sepsis reaches up to eleven million people, and the number of deaths from sepsis is even higher than those from cancer. We believe that the detection of MRSA is necessary.Staphylococcus aureus is the most common pathogen of sepsis. Methicillin-resistant Staphylococcus aureus (MRSA) or Multiple-resistant Staphylococcus aureus is a distinct strain of Staphylococcus aureus. It has mecA gene which codes for penicillin binding protein 2a (PBP 2A) that will remain active under beta lactams antibiotics. This gives bacterial the ability to grow under concentrations of beta-lactam antibiotics which leads to MRSA's resistance to almost all the different penicillin-type antibiotics including methicillin and other beta-lactamase-resistant penicillins.To detect MRSA in the shortest possible time, we adopt field-effect transistor (FET) biosensor for the real-time detection of binding reactions between DNA probe and cDNA. We select DNA probe sequence of mecA to be the aptamer and immobilize probe DNA which are complementary to the target cDNA on the sensor. This process allows DNA strands to attach to the gold surface. After that, we detect the binding reaction of DNA probe and cDNA by analyzing electrical response of field-effect transistor (FET). We can observe that the Id current changes after cDNA hybridizes with DNA probe.In conclusion, in our research results, Field-effect transistor (FET) biosensor can detect concentration ranging from 1fM to 1pM. In addition, we can achieve other advantages such as more portable, higher sensitivity, real-time monitoring capability, and lower detection limits. With this rapid detection procedure, we can do early diagnosis and treatment, thus improving the quality of human life. Keywords: FET, EDL, Aptamer, DNA, MRSA Figure 1

Spectroelectrochemical Setup for Probing Reactions on Electrodes and in Electrolytes

The combination of electrochemistry with vibrational spectroscopy is a powerful tool for studying electrochemical reactions, battery research, and failure analysis. Each molecule has a unique infrared and Raman signature providing great specificity in the analysis of the molecular change during electrochemical reactions.An overview of the spectroelectrochemical accessories for probing reactions on electrodes and in electrolytes will be presented. The optimization of the setup and details of communication between the potentiostat and the spectrometer will be discussed. Examples of applications will include electro-oxidation of metal-organic complexes, carbon analysis in flexible electrodes, and chemical mapping of the solid electrolyte interface of lithium metal battery.

Electrochemical Probing of Human Liver Subcellular S9 Fractions for Drug Metabolite Synthesis.

Human liver subcellular fractions, including liver microsomes (HLM), liver cytosol fractions, and S9 fractions, are extensively utilized in in vitro assays to predict liver metabolism. The S9 fractions are supernatants of human liver homogenates that contain both microsomes and cytosol, which include most cytochrome P450 (CYP) enzymes and soluble phase II enzymes such as glucuronosyltransferases and sulfotransferases. This study reports on the direct electrochemistry and biocatalytic features of redox-active enzymes in S9 fractions for the first time. We investigated the electrochemical properties of S9 films by immobilizing them onto a high-purity graphite (HPG) electrode and performing cyclic voltammetry under anaerobic (Ar-saturated) and aerobic (O2-saturated) conditions. The heterogeneous electron transfer rate between the S9 film and the HPG electrode was found to be 14 ± 3 s-1, with a formal potential of -0.451 V vs. Ag/AgCl reference electrode, which confirmed the electrochemical activation of the FAD/FMN cofactor containing CYP450-reductase (CPR) as the electron receiver from the electrode. The S9 films have also demonstrated catalytic oxygen reduction under aerobic conditions, identical to HLM films attached to similar electrodes. Additionally, we investigated CYP activity in the S9 biofilm for phase I metabolism using diclofenac hydroxylation as a probe reaction and identified metabolic products using liquid chromatography-mass spectrometry (LC-MS). Investigating the feasibility of utilizing liver S9 fractions in such electrochemical assays offers significant advantages for pharmacological and toxicological evaluations of new drugs in development while providing valuable insights for the development of efficient biosensor and bioreactor platforms.

An efficient technology for dye intermediate production: Process intensification of catalytic hydrogenation of aromatic nitrocompounds in a rotating packed bed reactor

AbstractThe rotating packed bed (RPB) is suitable for catalytic hydrogenation of aromatic nitrocompounds whose reaction rate is limited by the mass transfer rate. However, the matching mechanism between the mass transfer rate and intrinsic reaction rate in the RPB reactor is still unclear. In this work, the matching relationship in the RPB reactor is studied by combining the characteristics of mass transfer and reaction in detail. Effects of various operating conditions on the gas–liquid mass transfer coefficient up to 0.31/s, under working conditions were studied and the mass transfer correlation was proposed. The hydrogenation of p‐nitroanisole was used as a probe reaction to analyze the matching mechanism. Various aromatic nitrocompounds in the RPB and stirred tank reactors were investigated. The reaction efficiency of the former is 5–20 times that of the latter, which further explained the universality of the matching mechanism in the RPB reactor.