ABSTRACT
Electrochemiluminescence (ECL) is a powerful analytical approach that enables the optical readout of electrochemical processes. Over the last few years, ECL has gained considerable attention due to its large number of applications, including chemical sensing, bioanalysis and microscopy. In these fields, the promotion of ECL at bipolar electrodes has offered unprecedented opportunities thanks to wireless electrochemical addressing. Herein, we take advantage of the synergy between ECL and bipolar electrochemistry (BE) for imaging light-emitting layers shaped by hydrodynamics, polarization effects and the nature of the electrochemical reactions taking place wirelessly on a rotating bipolar electrode. The proof-of-principle is established with the model ECL system [Ru(bpy)3]2+/tri-n-propylamine. Interestingly, the ECL-emitting region moves and expands progressively from the anodic bipolar pole to the cathodic one where ECL reactants should neither be generated nor ECL be observed. Therefore, it shows a completely unusual behavior in the ECL field since the region where ECL reagents are oxidized does not coincide with the zone where ECL light is emitted. In addition, the ECL patterns change progressively to an "ECL croissant" and then to a complete ring shape due to the hydrodynamic convection. Such an approach allows the visualization of complex light-emitting patterns, whose shape is directly controlled by the rotation speed, chemical reactivity and BE-induced polarization. Indeed, the bipolar electrochemical addressing of the electrode breaks the circular symmetry of the reported rotating system. This unexplored and a priori simple configuration yields unique ECL behavior and raises new curious questions from the theoretical and experimental points of view in analytical chemistry. Finally, this novel wireless approach will be useful for the development of original ECL systems for analytical chemistry, studies of electrochemical reactivity, coupling microfluidics with ECL and imaging.
ABSTRACT
An electromagnet is a particular device that takes advantage of electrical currents to produce concentrated magnetic fields. The most well-known example is a conventional solenoid, having the form of an elongated coil and creating a strong magnetic field through its center when it is connected to a current source. Spontaneous redox reactions located at opposite ends of an anisotropic Janus swimmer can effectively mimic a standard power source, due to their ability to wirelessly generate a local electric current. Herein, we propose the coupling of thermodynamically spontaneous redox reactions occurring at the extremities of a hybrid Mg/Pt Janus swimmer with a solenoidal geometry to generate significant magnetic fields. These chemically driven electromagnets spontaneously transform the redox-induced electric current into a magnetic field with a strength in the range of µT upon contact with an acidic medium. Such on-board magnetization allows them to perform compass-like rotational motion and magnetotactic displacement in the presence of external magnetic field gradients, without the need of using ferromagnetic materials for the swimmer design. The torque force experienced by the swimmer is proportional to the internal redox current, and by varying the composition of the solution, it is possible to fine-tune its angular velocity.
ABSTRACT
Astrocytes form an integral component of the neurovascular unit, ensheathing brain blood vessels with projections high in aquaporin-4 (AQP4) expression. These AQP4-rich projections facilitate interaction between the vascular endothelium, astrocytes, and neurons, and help stabilize vascular morphology. Studies using preclinical models of psychological stress and post-mortem tissue from patients with major depressive disorder (MDD) have reported reductions in AQP4, loss of astrocytic structures, and vascular impairment in the prefrontal cortex (PFC). Though compelling, the role of AQP4 in mediating stress-induced alterations in blood vessel function and behavior remains unclear. Here, we address this, alongside potential sex differences in chronic unpredictable stress (CUS) effects on astrocyte phenotype, blood-brain barrier integrity, and behavior. CUS led to pronounced shifts in stress-coping behavior and working memory deficits in male -but not female- mice. Following behavioral testing, astrocytes from the frontal cortex were isolated for gene expression analyses. We found that CUS increased various transcripts associated with blood vessel maintenance in astrocytes from males, but either had no effect on- or decreased- these genes in females. Furthermore, CUS caused a reduction in vascular-localized AQP4 and elevated extravasation of a small molecule fluorescent reporter (Dextran) in the PFC in males but not females. Studies showed that knockdown of AQP4 in the PFC in males is sufficient to disrupt astrocyte phenotype and increase behavioral susceptibility to a sub-chronic stressor. Collectively, these findings provide initial evidence that sex-specific alterations in astrocyte phenotype and neurovascular integrity in the PFC contribute to behavioral and cognitive consequences following chronic stress.
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Graphene has gained substantial research interest in many fields due to its remarkable properties among many other two-dimensional materials. In this study, we propose a wireless electrochemical approach, bipolar electrochemistry, for the precise modification of single layers of graphene at predefined locations, such as distinct edges or corners, with a variety of metals or polymers, thus enabling the elaboration of multi-functional monolayer graphene sheets. We illustrate the concept e. g. by depositing multiple metals, or platinum and a catalyst-containing porous polymer on the same graphene sheet, but at separate corners. This configuration allows activating chemiluminescence on the polymer spot, and simultaneously generates the driving force for autonomous motion on the Pt side through the catalytic decomposition of hydrogen peroxide into oxygen bubbles. This integration of different chemical features on the same object, exemplified by these proof-of-principle experiments, enhances the functionality of two-dimensional materials, paving the way for the use of these hybrid materials for a variety of applications, ranging from sensing and catalysis to targeted delivery.
ABSTRACT
Electrochemistry-based light-emitting devices have gained considerable attention in different applications such as sensing and optical imaging. In particular, such systems are an interesting alternative for the development of multimodal light-emitting platforms. Herein we designed a multicolor light-emitting array, based on the electrochemical switch-on of light-emitting diodes (LEDs) with a different intrinsic threshold voltage. Thermodynamically and kinetically favored coupled redox reactions, i. e. the oxidation of Mg and the reduction of protons on Pt, act as driving force to power the diodes. Moreover, this system enables to trigger an additional light emission based on the interfacial reductive-oxidation electrochemiluminescence (ECL) mechanism of the Ru(bpy)3 2+/S2O8 2- system. The synergy between these light-emission pathways offers a multimodal platform for the straightforward optical readout of physico-chemical information based on composition changes of the solution.
ABSTRACT
Water splitting has become a sustainable and clean alternative for hydrogen production. Commonly, the efficiency of such reactions is intimately related to the physico-chemical properties of the catalysts that constitute the electrolyzer. Thus, the development of simple and fast methods to evaluate the electrocatalytic efficiency of an electrolyzer is highly required. In this work, we present an unconventional method based on the combination of bipolar electrochemistry and light-emitting diodes, which allows the evaluation of the electrocatalytic performance of the two types of catalysts, composing an electrolyzer, namely for oxygen and hydrogen evolution reactions, respectively. The integrated light emission of the diode acts as an optical readout of the electrocatalytic information, which simultaneously depends on the composition of the anode and the cathode. The electrocatalytic activity of Au, Pt, and Ni electrodes, connected to the LED in multiple anode/cathode configurations, towards the water splitting reactions has been evaluated. The efficiency of the electrolyzer can be represented in terms of the onset electric field (ϵonset) for light emission, obtaining variations that are in agreement with data reported with conventional electrochemistry. This work introduces a straightforward method for evaluating electrocatalysts and underscores the importance of material characterization in developing efficient electrolyzers for hydrogen production.
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Mutations in histone H3.3-encoding genes causing mutant histone tails are associated with specific cancers such as pediatric glioblastomas (H3.3-G34R/V) and giant cell tumor of the bone (H3.3-G34W). The mechanisms by which these mutations promote malignancy are not completely understood. Here we show that cells expressing H3.3-G34W exhibit DNA double-strand breaks (DSBs) repair defects and increased cellular sensitivity to ionizing radiation (IR). Mechanistically, H3.3-G34W can be deposited to damaged chromatin, but in contrast to wild-type H3.3, does not interact with non-homologous end-joining (NHEJ) key effectors KU70/80 and XRCC4 leading to NHEJ deficiency. Together with defective cell cycle checkpoints reported previously, this DNA repair deficiency in H3.3-G34W cells led to accumulation of micronuclei and cytosolic DNA following IR, which subsequently led to activation of the cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING) pathway, thereby inducing release of immune-stimulatory cytokines. These findings suggest a potential for radiotherapy for tumors expressing H3.3-G34W, which can be further improved by combination with STING agonists to induce immune-mediated therapeutic efficacy.
Subject(s)
DNA Repair-Deficiency Disorders , Histones , Child , Humans , Histones/genetics , Nucleotidyltransferases/genetics , Immunity , DNAABSTRACT
Chirality plays a crucial role in different research fields, ranging from fundamental physico-chemistry to applied aspects in materials science and medicine. In this context, enantioselective loading and pumping of chiral analytes for analysis, separation, and cargo delivery applications is an interesting scientific challenge. Herein, we introduce artificial chiral soft electromechanical pumps based on a bi-layer film built up by electrodepositing polypyrrole and an inherently chiral conducting oligomer at its internal surface. The enantioselective device can be driven by bipolar electrochemistry to act as a pump, allowing the selective loading and separation of different chiral analytes injected as pure enantiomers and in racemic form (i.e., doxorubicin, a chemotherapy drug, limonene, carvone, and a chiral ferrocene). The synergy between wireless electromechanical actuation and inherent enantiodiscrimination features makes these actuators excellent candidates for the controlled handling of chiral molecules in the frame of potential applications ranging from analysis to drug delivery.
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The development of new pharmaceutical compounds is challenging because most of them are based on enantiopure chiral molecules, which exhibit unique properties for therapy. However, the synthesis of pharmaceutical compounds in the absence of a chiral environment naturally leads to a racemic mixture. Thus, to control their synthesis, an asymmetric environment is required, and chiral homogeneous catalysts are typically used to synthesize enantiopure pharmaceutical compounds (EPC). Nevertheless, homogeneous catalysts are difficult to recover after the reaction, generating additional problems and costs in practical processes. Thus, the development of chiral heterogeneous catalysts is a timely topic. In a more general context, such chiral materials cannot only be used for synthesis, but also to recognize and separate enantiomers. In the frame of these different challenges, we give in this review a short introduction to strategies to extrinsically and intrinsically modify heterogeneous metal matrixes for the enantioselective synthesis, recognition, and separation of chiral pharmaceutical compounds.
Subject(s)
Metals , Stereoisomerism , Pharmaceutical PreparationsABSTRACT
Objective: Public health surveillance is essential for improving community health. The Cardiac Arrest Registry to Enhance Survival (CARES) is a surveillance system for out-of-hospital cardiac arrest (OHCA). We describe results of the organized statewide implementation of Ohio CARES. Methods: We performed a retrospective analysis of CARES enactment in Ohio. Key elements included: establishment of statewide leadership, appointment of a dedicated coordinator, conversion to a statewide subscription, statewide dissemination of information, fundraising from internal and external stakeholders, and conduct of resuscitation academies. We identified all adult (≥18 years) OHCA reported in the registry during 2013-2020. We evaluated OHCA characteristics before (2013-2015) and after (2016-2019) statewide implementation using chi-square test. We evaluated trends in OHCA outcomes using the Cochran-Armitage test of trend. Results: Statewide CARES promotion increased participation from 2 (urban) to 136 (129 urban, 7 rural) EMS agencies. Covered population increased from 1.2 M (10% of state) to 4.8 M (41% of state). After statewide implementation, OHCA populations increased male (58.1% vs 60.8%, p < 0.01), white (50.1% vs 63.7%, p < 0.01), bystander witnessed (26.9% vs 32.9%, p < 0.01) OHCAs. Bystander CPR (34.7% vs 33.2%, p = 0.22), bystander AED (13.5% vs 12.3%, p = 0.55) and initial rhythm (shockable 18.0% vs 18.3%, p = 0.32) did not change. From 2013 to 2019 there were temporal increases in ROSC (29.7% to 31.9%, p-trend = 0.028), survival (7.4% to 12.3%, p-trend < 0.001) and survival with good neurologic outcome (5.6% to 8.6%, p-trend = 0.047). Conclusion: The organized statewide implementation of CARES in Ohio was associated with marked increases in community uptake and concurrent observed improvements in patient outcomes. These results highlight key lessons for community-wide fostering of OHCA surveillance.
ABSTRACT
Asymmetric modification of particles with various patches of different composition and size at predefined positions is an important challenge in contemporary surface chemistry, as such particles have numerous potential applications, ranging from materials science and (photo)catalysis to self-assembly and drug delivery. However, approaches allowing the synthesis of this kind of complex objects in the bulk of a solution in a straightforward way are currently lacking. In this context, bipolar electrochemistry (BE) is a powerful technique for the asymmetric modification of conducting objects. Herein, this approach is used for the highly controlled modification of particles with different metal patches, generated at specific locations of isotropic objects. The synthesis is carried out in the bulk of the solution and leads to predefined patterns of increasing complexity, including even a specific chiral arrangement of the patches.
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Cable bacteria are multicellular, filamentous bacteria that use internal conductive fibers to transfer electrons over centimeter distances from donors within anoxic sediment layers to oxygen at the surface. We extracted the fibers and used them as free-standing bio-based electrodes to investigate their electrocatalytic behavior. The fibers catalyzed the reversible interconversion of oxygen and water, and an electric current was running through the fibers even when the potential difference was generated solely by a gradient of oxygen concentration. Oxygen reduction as well as oxygen evolution were confirmed by optical measurements. Within living cable bacteria, oxygen reduction by direct electrocatalysis on the fibers and not by membrane-bound proteins readily explains exceptionally high cell-specific oxygen consumption rates observed in the oxic zone, while electrocatalytic water oxidation may provide oxygen to cells in the anoxic zone.
Subject(s)
Geologic Sediments , Sulfides , Electron Transport , Geologic Sediments/microbiology , Sulfides/metabolism , Oxidation-Reduction , Bacteria/metabolism , Oxygen/metabolism , Water/metabolism , ElectrodesABSTRACT
PURPOSE: To utilize 4âD flow MRI to acquire normal values of "conventional 2âD flow MRI parameters" in healthy volunteers in order to replace multiple single 2âD flow measurements with a single 4âD flow acquisition. MATERIALS AND METHODS: A kt-GRAPPA accelerated 4âD flow sequence was used. Flow volumes were assessed by forward (FFV), backward (BFV), and net flow volumes (NFV) [ml/heartbeat] and flow velocities by axial (VAX) and absolute velocity (VABS) [m/s] in 116 volunteers (58 females, 43â±â13 years). The aortic regurgitant fraction (RF) was calculated. RESULTS: The sex-neutral mean FFV, BFV, NFV, and RF in the ascending aorta were 93.5â±â14.8, 3.6â±â2.8, 89.9â±â0.6âml/heartbeat, and 3.9â±â2.9â%, respectively. Significantly higher values were seen in males regarding FFV, BFV, NFV and RF, but there was no sex dependency regarding VAX and VABS.âThe mean maximum VAX was lower (1.01â±â0.31âm/s) than VABS (1.23â±â0.35âm/s). We were able to determine normal ranges for all intended parameters. CONCLUSION: This study provides quantitative 4âD flow-derived thoracic aortic normal values of 2âD flow parameters in healthy volunteers. FFV, BFV, NFV, and VAX did not differ significantly from single 2âD flow acquisitions and could therefore replace time-consuming multiple single 2âD flow acquisitions. VABS should not be used interchangeably. KEY POINTS: · 4âD flow MRI can be used to replace 2âD flow MRI measurements.. · The parameter absolute velocities can be assessed by 4âD flow MRI.. · There are sex-dependent differences regarding forward, backward, net aortic blood flow and the aortic valve regurgitant fraction..
Subject(s)
Aorta , Magnetic Resonance Imaging , Male , Female , Humans , Reference Values , Healthy Volunteers , Blood Flow Velocity/physiology , Aorta/diagnostic imaging , Imaging, Three-Dimensional , Reproducibility of Results , Aorta, Thoracic/diagnostic imagingABSTRACT
Electromagnetically induced rotation is a key process of many technological systems that are used in daily life, especially for energy conversion. In this context, the Lorentz force-induced deviation of charges is a crucial physical phenomenon to generate rotation. Herein, they combine the latter with the concept of bipolar electrochemistry to design a wireless magnetoelectrochemical rotor. Such a device can be considered as a wet analog of a conventional electric motor. The main driving force that propels this actuator is the result of the synergy between the charge-compensating ion flux along a bipolar electrode and an external magnetic field applied orthogonally to the surface of the object. The trajectory of the wirelessly polarized rotor can be controlled by the orientation of the magnetic field relative to the direction of the global electric field, producing a predictable clockwise or anticlockwise motion. Fine-tuning of the applied electric field allows for addressing conducting objects having variable characteristic lengths.
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Invited for the cover of this issue are the groups of Chularat Wattanakit and Alexander Kuhn at the Vidyasirimedhi Institute of Science and Technology and the University of Bordeaux. The two tunnels in the image illustrate the entrance into a porous heterogeneous catalyst for the stereoselective transformation of adrenalone into the desired epinephrine stereoisomer. Read the full text of the article at 10.1002/chem.202302054.
ABSTRACT
Artificial actuators have been extensively studied due to their wide range of applications from soft robotics to biomedicine. Herein we introduce an autonomous bi-enzymatic system where reversible motion is triggered by the spontaneous oxidation and reduction of glucose and oxygen, respectively. This chemo-mechanical actuation is completely autonomous and does not require any external trigger to induce self-sustained motion. The device takes advantage of the asymmetric uptake and release of ions on the anisotropic surface of a conducting polymer strip, occurring during the operation of the enzymes glucose oxidase and bilirubin oxidase immobilized on its surface. Both enzymes are connected via a redox polymer at each extremity of the strip, but at the opposite faces of the polymer film. The time-asymmetric consumption of both fuels by the enzymatic reactions produces a double break of symmetry of the film, leading to autonomous actuation. An additional break of symmetry, introduced by the irreversible overoxidation of one extremity of the polymer film, leads to a crawling-type motion of the free-standing polymer film. These reactions occur in a virtually unlimited continuous loop, causing long-term autonomous actuation of the device.
ABSTRACT
Multimodal imaging is a powerful and versatile approach that integrates and correlates multiple optical modalities within a single device. This concept has gained considerable attention due to its potential applications ranging from sensing to medicine. Herein, we develop several wireless multimodal light-emitting chemical systems by coupling two light sources based on different physical principles: electrochemiluminescence (ECL) occurring at the electrode interface and a light-emitting diode (LED) switched on by an electrochemically triggered electron flow. Endogenous (thermodynamically spontaneous redox process) and exogenous (requiring an external power source) bipolar electrochemistry acts as a driving force to trigger both light emissions at different wavelengths. The results presented here interconnect optical imaging and electrochemical reactions, providing a novel and so far unexplored alternative to design autonomous hybrid systems with multimodal and multicolor optical readouts for complex bio-chemical systems.