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The growing demand for portable sensors for point-of-care (POC) and onsite health monitoring has led to significant interest in developing suitable power sources. In this study, we developed a microfluidic chip-integrated reverse electrodialysis (μRED) system for ecofriendly power generation with monolithic operation. Leveraging its fully ionic characteristic, μRED was successfully applied to an ionic diode, thereby demonstrating its capability for seamless integration. The feasibility of operating a bipolar electrode sensor without an external power supply was demonstrated, highlighting its broad applicability in electrochemical portable sensors. μRED has great potential for future applications, including electrochemical sensors for POC diagnostics and wearable devices., Competing Interests: Competing interests statement:The authors declare no competing interest.

Lithium-ion batteries are among the most important energy-storage devices. In this regard, nickel-cobalt-manganese (NCM) cathodes are widely used because of their high energy density and stability. Cu on NCM can enhance the overall performance by aiding lithium-ion transport through cation mixing; however, it leads to issues, such as internal short circuits. The precipitation pH of Cu is high, making its chemical separation from the NCM challenging. Given the impacts and the challenge of separation, an accurate quantification of the residual Cu content in the NCM cathode is essential. Inductively coupled plasma methods struggle with the accurate quantification of trace impurities in NCM owing to the high contents of material elements, leading to instrument malfunction and time-consuming labor. In this study, the introduction of electrochemical methods significantly weakened the matrix effect and facilitated the pretreatment of the solution. In particular, a thin-film electrode (TFE) made of Rh allowed quantification of the Cu present in commercial NCM powder. Cyclic voltammetry and an electrochemical quartz crystal microbalance were used to confirm the formation of two types of underpotential deposition (UPD) Cu on the Rh TFE. Square-wave voltammetry was used to analyze the kinetic differences in Cu upd and quantify trace amounts of Cu with high sensitivity. The results included a relative standard deviation of 2.54%, linear range of 13-450 ppb, and limit of detection of 3.9 ppb. The method was successfully applied to commercial NCM products, where the standard addition method determined Cu content in the range 40-60 ppb. This method provides standardized guidelines for both laboratory and industry for evaluating the effects of impurities across various NCM cathodes., Competing Interests: The authors declare no competing financial interest., (© 2025 The Authors. Published by American Chemical Society.)

Drug delivery systems hold promise for delivering cytotoxic drugs by controlling the timing and location of the drug release. However, conventional delivery mechanisms often fall short of achieving spatiotemporally controlled yet sustained release, which is crucial for ensuring drug efficacy and minimizing impact on surrounding tissues. Here, an ionic diode-based drug delivery system is reported that is controlled by an electric potential and capable of releasing drugs at scales ranging from nanogram to microgram. The migrated drug is slowly but continuously diffused to the lesion through the hydrogel at the desired rate. The ionic diode provides flow-free drug delivery while minimizing unintended drug leakage over prolonged periods. Implanted in a freely moving tumor-bearing mouse model, the system filled with doxorubicin demonstrated superior anti-tumor efficacy and minimal off-target immune toxicity compared to the intratumoral injection of free doxorubicin. With its mechanically compliant and biocompatible components, the system offers a safe and readily translatable approach to patients with surgically unresectable tumors., (© 2024 Wiley‐VCH GmbH.)

The selection of electrode material is a critical factor that determines the selectivity of electrochemical organic reactions. However, the fundamental principles governing this relationship are still largely unexplored. Herein, we demonstrate a photoelectrocatalytic (PEC) system as a promising reaction platform for the selective radical-radical coupling reaction owing to the inherent charge-transfer properties of photoelectrocatalysis. As a model reaction, the radical trifluoromethylation of arenes is shown on hematite photoanodes without employing molecular catalysts. The PEC platform exhibited superior mono- to bis-trifluoromethylated product selectivity compared to conventional electrochemical methods utilizing conducting anodes. Electrochemical and density functional theory (DFT) computational studies revealed that controlling the kinetics of anodic oxidation of aromatic substrates is essential for increasing reaction selectivity. Only the PEC configuration could generate sufficiently high-energy charge carriers with controlled kinetics due to the generation of photovoltage and charge-carrier recombination, which are characteristic features of semiconductor photoelectrodes. This study opens a novel approach towards selective electrochemical organic reactions through understanding the intrinsic physicochemical properties of semiconducting materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Scanning electrochemical cell microscopy (SECCM) has been used to explore structure-electrocatalytic activity relationships through high-resolution mapping of local activities of electrocatalysts. However, utilizing SECCM in strongly alkaline conditions presents a significant challenge due to the high wettability of the alkaline electrolyte leading to a substantial instability of the droplet in contact with the sample surface, and hence to unpredictable wetting and spreading of the electrolyte. The spreading phenomena in SECCM is confirmed by the electrochemical response of a free-diffusing redox probe and finite element method (FEM) simulations. Considering the significance of alkaline electrolytes in electrocatalysis, these wetting issues restrict the application of SECCM for electrocatalyst elucidation in highly alkaline electrolytes. We resolve this issue by incorporating a small percentage of polyvinylpyrrolidone (PVP) in the electrolyte inside the SECCM capillary to increase the surface tension of the electrolyte. To demonstrate successful wetting mitigation and stable SECCM mapping, we performed oxygen evolution reaction (OER) mapping on polycrystalline Pt by using 1 M KOH with an optimized PVP concentration. The OER activity maps correlated with the orientation of the exposed facets determined by electron backscatter diffraction and reveal different activities between Pt facets, hence confirming our methodology for exploring electrocatalytic activities in single facet scale in concentrated alkaline media. Interestingly, the maximum OER current density was highest for (110) and (111) which contradicts the activity trends in acidic electrolyte for which (100) is most active for the OER., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Blood cell counting typically requires complex machinery. Flow cytometers used for this purpose involve precise optical alignment, costly detectors, and pretreatment with fluorescent labels. Coulter countertype devices, which monitor ion current, are simpler. However, conventional Coulter counters provide only information about size, making it impossible to distinguish similarly sized lymphocytes from red blood cells (RBCs). Inspired by the fact that RBCs have an exceptionally high propensity to absorb light and convert it to heat, i.e., photothermal effect, this study proposes integrating photothermal phenomena into a microfluidic Coulter counting chip. Photothermal heat selectively amplifies the ion current from RBCs over other components including lymphocytes. The combination of ion current monitoring and the photothermal effect for RBC counting suggests an evolution toward versatile flow cytometers.

High-entropy alloys (HEAs), especially in the form of compositional complex solid solutions (CCSS), have gained attention in the field of electrocatalysis. However, exploring their vast composition space concerning their electrocatalytic properties imposes significant challenges. Scanning electrochemical cell microscopy (SECCM) offers high-speed electrochemical analysis on surface areas with a lateral resolution down to tens of nm. However, high-precision piezo positioners often used for the motion of the tip limit the area of SECCM scans to the motion range of the piezo positioners which is typically a few tens of microns. To bridge this experimental gap, the study proposes a long-range SECCM system with a rapid gas-exchange environmental cell for high-throughput electrochemical characterization of 100 mm diameter HEA thin-film material libraries (ML) obtained by combinatorial co-sputtering. Due to the gas-liquid interface at the positioned SECCM droplet on the sample, high-throughput evaluation under industrial current density conditions becomes feasible. This allows the direct correlation between electrocatalytic activity and material composition with high statistical reliability. The multidimensional data obtained accelerates materials discovery, development, and optimization., (© 2023 The Authors. Small Methods published by Wiley‐VCH GmbH.)

Interactions between endothelial cells (ECs) and mural pericytes (PCs) are critical in maintaining the stability and function of the microvascular wall. Abnormal interactions between these two cell types are a hallmark of progressive fibrotic diseases such as systemic sclerosis (also known as scleroderma). However, the role of PCs in signaling microvascular dysfunction remains underexplored. We hypothesized that integrin-matrix interactions contribute to PC migration from the vascular wall and conversion into interstitial myofibroblasts. Herein, pro-inflammatory tumor necrosis factor α (TNFα) or a fibrotic growth factor [transforming growth factor β1 (TGF-β1)] were used to evaluate human PC inflammatory and fibrotic phenotypes by assessing their migration, matrix deposition, integrin expression, and subsequent effects on endothelial dysfunction. Both TNFα and TGF-β1 treatment altered integrin expression and matrix protein deposition, but only fibrotic TGF-β1 drove PC migration in an integrin-dependent manner. In addition, integrin-dependent PC migration was correlated to changes in EC angiopoietin-2 levels, a marker of vascular instability. Finally, there was evidence of changes in vascular stability corresponding to disease state in human systemic sclerosis skin. This work shows that TNFα and TGF-β1 induce changes in PC integrin expression and matrix deposition that facilitate migration and reduce vascular stability, providing evidence that microvascular destabilization can be an early indicator of tissue fibrosis., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Monitoring the dendritic electrodeposition process is crucial in various fields such as energy storage devices and sensors. A variety of in situ dendritic growth monitoring methods have been developed, especially for battery applications, but they require specialized cells and equipment and are often invasive, making them unsuitable for various electrochemical systems and commercial batteries. To address these challenges, a real-time impedance analysis technique was used to determine dendritic electrodeposition on microelectrodes. The "effective size" of the electrodeposit was extracted from the impedance data, and the dendritic growth was assessed in real-time by comparing "effective size" to a theoretical radius assuming hemispherical growth. The technique was validated using scanning electron microscopy imaging and finite element method simulation. Initially applied to gold electrodeposition, the method was extended to zinc electrodeposition, demonstrating potential utilization for energy storage systems.

Advancements in neural interface technologies have enabled the direct connection of neurons and electronics, facilitating chemical communication between neural systems and external devices. One promising approach is a synaptogenesis-involving method, which offers an opportunity for synaptic signaling between these systems. Janus synapses, one type of synaptic interface utilizing synaptic cell adhesion molecules for interface construction, possess unique features that enable the determination of location, direction of signal flow, and types of neurotransmitters involved, promoting directional and multifaceted communication. This study presents the first successful establishment of a Janus synapse between dopaminergic (DA) neurons and abiotic substrates by using a neuroligin-2 (NLG2)-mediated synapse-inducing method. NLG2 immobilized on gold-coated microspheres can induce synaptogenesis upon contact with spatially isolated DA axons. The induced DA Janus synapses exhibit stable synaptic activities comparable to that of native synapses over time, suggesting their suitability for application in neural interfaces. By calling for DA presynaptic organizations, the NLG2-immobilized abiotic substrate is a promising tool for the on-site detection of synaptic dopamine release.

A practical method for C(sp 3 )-B bond activation was developed. Using a combination of alkyl trifluoroborates and N -iodosuccinimide (NIS), various C(sp 3 )-heteroatom bonds were readily generated in an efficient manner. Mechanistic studies revealed the bifunctional ability of NIS: mediating the formation of reactive halogenated intermediates and activating them via halogen bonding. This electrophilic activation of the reaction center enables the utilization of general heteroatom nucleophiles, which are used in a limited capacity in traditional 1,2-metalate rearrangements.

Metastatic brain cancer has poor prognosis due to challenges in both detection and treatment. One contributor to poor prognosis is the blood-brain barrier (BBB), which severely limits the transport of therapeutic agents to intracranial tumors. During the development of brain metastases from primary breast cancer, the BBB is modified and is termed the 'blood-tumor barrier' (BTB). A better understanding of the differences between the BBB and BTB across cancer types and stages may assist in identifying new therapeutic targets. Here, we utilize a tissue-engineered microvessel model with induced pluripotent stem cell (iPSC)-derived brain microvascular endothelial-like cells (iBMECs) and surrounded by human breast metastatic cancer spheroids with brain tropism. We directly compare BBB and BTB in vitro microvessels to unravel both physical and chemical interactions occurring during perivascular cancer growth. We determine the dynamics of vascular co-option by cancer cells, modes of vascular degeneration, and quantify the endothelial barrier to antibody transport. Additionally, using bulk RNA sequencing, ELISA of microvessel perfusates, and related functional assays, we probe early brain endothelial changes in the presence of cancer cells. We find that immune cell adhesion and endothelial turnover are elevated within the metastatic BTB, and that macrophages exert a unique influence on BTB identity. Our model provides a novel three-dimensional system to study mechanisms of cancer-vascular-immune interactions and drug delivery occurring within the BTB., (© 2023. The Author(s).)

The blood-brain barrier (BBB) is located at the interface between the vascular system and the brain parenchyma, and is responsible for communication with systemic circulation and peripheral tissues. During life, the BBB can be subjected to a wide range of perturbations or stresses that may be endogenous or exogenous, pathological or therapeutic, or intended or unintended. The risk factors for many diseases of the brain are multifactorial and involve perturbations that may occur simultaneously (e.g., two-hit model for Alzheimer's disease) and result in different outcomes. Therefore, it is important to understand the influence of individual perturbations on BBB function in isolation. Here we review the effects of eight perturbations: mechanical forces, temperature, electromagnetic radiation, hypoxia, endogenous factors, exogenous factors, chemical factors, and pathogens. While some perturbations may result in acute or chronic BBB disruption, many are also exploited for diagnostic or therapeutic purposes. The resultant outcome on BBB function depends on the dose (or magnitude) and duration of the perturbation. Homeostasis may be restored by self-repair, for example, via processes such as proliferation of affected cells or angiogenesis to create new vasculature. Transient or sustained BBB dysfunction may result in acute or pathological symptoms, for example, microhemorrhages or hypoperfusion. In more extreme cases, perturbations may lead to cytotoxicity and cell death, for example, through exposure to cytotoxic plaques., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhao, Chung, Guo, Jamieson, Liang, Linville, Pessell, Wang and Searson.)

Living cells efflux intracellular ions for maintaining cellular life, so intravital measurements of specific ion signals are of significant importance for studying cellular functions and pharmacokinetics. In this work, de novo synthesis of artificial K + -selective membrane and its integration with polyelectrolyte hydrogel-based open-junction ionic diode (OJID) is demonstrated, achieving a real-time K + -selective ion-to-ion current amplification in complex bioenvironments. By mimicking biological K + channels and nerve impulse transmitters, in-line K + -binding G-quartets are introduced across freestanding lipid bilayers by G-specific hexylation of monolithic G-quadruplex, and the pre-filtered K + flow is directly converted to amplified ionic currents by the OJID with a fast response time at 100 ms intervals. By the synergistic combination of charge repulsion, sieving, and ion recognition, the synthetic membrane allows K + transport exclusively without water leakage; it is 250× and 17× more permeable toward K + than monovalent anion, Cl - , and polyatomic cation, N-methyl-d-glucamine + , respectively. The molecular recognition-mediated ion channeling provides a 500% larger signal for K + as compared to Li + (0.6× smaller than K + ) despite the same valence. Using the miniaturized device, non-invasive, direct, and real-time K + efflux monitoring from living cell spheroids is achieved with minimal crosstalk, specifically in identifying osmotic shock-induced necrosis and drug-antidote dynamics., (© 2023 Wiley-VCH GmbH.)

Viruses have unique coat proteins that are genetically modifiable. Their surface can serve as a nano-template on which electroactive molecules are immobilized. In this study, we report filamentous bacteriophage as a backbone to which redox mediators are covalently and densely tethered, constructing redox nanowire, i.e. an electron conducting biomaterial. The highly ordered coat proteins of a filamentous bacteriophage provide flexible and biocompatible platform to constitute a biohybrid redox nanowire. Incorporating bacteriophage and redox molecules form an entangled assembly of nanowires enabling facile electron transfer. Electron transfer among the molecular mediators in the entangled assembly originates apparent electron diffusion of which the electron transfer rate is comparable to that observed in conventional redox polymers. Programming peptide terminals suggests further enhancement in electron mediation by increasing redox species mobility. In addition, the redox nanowire film functions as a favorable matrix for enzyme encapsulation. The stability of the enzymes entrapped in this unique matrix is substantially improved., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Two-electrode (2E) system of the interdigitated electrode array (IDA), which operates neither reference nor counter electrodes, has great potential to miniaturize multiplex immunoassay in a microfluidic chip for point-of-care testing. However, it is necessary to firmly immobilize the mediator layer on IDA made of indium tin oxide (ITO) which is chemically inert. It is important because the mediator determines the electrochemical potential in the 2E system, but the layer is easy to be detached during the washing processes of immunoassay. Here, we controlled the concentration of ethylenediamine (EDA) to generate a permeable and robust film to adhere to mediators on the ITO IDA chip. Electrooxidation of EDA yielded thin oligomeric ethyleneimine (OEI) film and it provided amine groups for immobilizing the mediator, poly(toluidine blue) (pTB), via common conjugation reaction. Despite repeated flows in the microchannel, which are essential for sensitive immunoassay, the pTB/OEI layer was hardly washed and still remained on the ITO IDA. Myoglobin was measured down to ∼ pg/mL level. Therefore, the ITO IDA modified with the OEI film in the 2E system constituted a stable platform that withstands washing steps for sensitive electrochemical detection in the miniaturized immunoassay., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Angiogenesis plays an essential role in embryonic development, organ remodeling, wound healing, and is also associated with many human diseases. The process of angiogenesis in the brain during development is well characterized in animal models, but little is known about the process in the mature brain. Here, we use a tissue-engineered post-capillary venule (PCV) model incorporating stem cell derived induced brain microvascular endothelial-like cells (iBMECs) and pericyte-like cells (iPCs) to visualize the dynamics of angiogenesis. We compare angiogenesis under two conditions: in response to perfusion of growth factors and in the presence of an external concentration gradient. We show that both iBMECs and iPCs can serve as tip cells leading angiogenic sprouts. More importantly, the growth rate for iPC-led sprouts is about twofold higher than for iBMEC-led sprouts. Under a concentration gradient, angiogenic sprouts show a small directional bias toward the high growth factor concentration. Overall, pericytes exhibited a broad range of behavior, including maintaining quiescence, co-migrating with endothelial cells in sprouts, or leading sprout growth as tip cells., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Seamless neural interfaces conjoining neurons and electrochemical devices hold great potential for highly efficient signal transmission across neural systems and the external world. Signal transmission through chemical sensing and stimulation via electrochemistry is remarkable because communication occurs through the same chemical language of neurons. Emerging strategies based on synaptic interfaces, iontronics-based neuromodulation, and improvements in selective neurosensing techniques have been explored to achieve seamless integration and efficient neuro-electronics communication. Synaptic interfaces can directly exchange signals to and from neurons, in a similar manner to that of chemical synapses. Hydrogel-based iontronic chemical delivery devices are operationally compatible with neural systems for improved neuromodulation. In this perspective, we explore developments to improve the interface between neurons and electrodes by targeting neurons or sub-neuronal regions including synapses. Furthermore, recent progress in electrochemical neurosensing and iontronics-based chemical delivery is examined., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Room temperature ionic liquids (RT-ILs) are promising electrolytes for electrocatalysis. Understanding the effects of the electrode-electrolyte interface structure on electrocatalysis in RT-ILs is important. Ultrafast mass transport of redox species in N-methyl-N-ethyl-pyrrolidinium polybromide (MEPBr 2n+1 ) enabled evaluation of the reorganization energy (λ), which reflects the solvation structure in the inner Helmholtz plane (IHP). λ was achieved by fitting the electron transfer rate-limited voltammogram at a Pt ultramicroelectrode (UME) to the Marcus-Hush-Chidsey model for heterogeneous electron transfer kinetics. However, it is time-consuming or even impossible to prepare electrode materials, including alloys of numerous compositions in the form of UME, for each experiment. Herein, we report a method to evaluate the λ of MEPBr 2n+1 by scanning electrochemical cell microscopy (SECCM), which allows high throughput electrochemical measurements using a single electrode with high spatial resolution. Fast mass transport in the nanosized SECCM tip is critical for achieving heterogeneous electron transfer-limited voltammograms. Furthermore, investigating λ on a high-entropy alloy materials library composed of Pt, Pd, Ru, Ir, and Ag suggests a negative correlation between λ and the work function. Given that the potential of zero charge correlates with the work function of electrodes, this can be attributed to the surface-charge sensitive ionic structure in the IHP of MEPBr 2n+1 , modulating the solvation energy of the redox-active species in the IHP.

In this study, an aqueous nonlinear synaptic element showing plasticity behavior is developed, which is based on the chemical processes in an ionic diode. The device is simple, fully ionic, and easily configurable, requiring only two terminals-for input and output-similar to biological synapses. The key processes realizing the plasticity features are chemical precipitation and dissolution, which occur at forward- or reverse-biased ionic diode junctions in appropriate reservoir electrolytes. Given that the precipitate acts as a physical barrier in the circuit, the above processes change the diode conductivity, which can be interpreted as adjusting "synaptic weight" of the system. By varying the operating conditions, we first demonstrate the four types of plasticity that can be found in biological system: long-term potentiation/depression and short-term potentiation/depression. The plasticity of the proposed iontronic device has characteristics similar to those of neural synapses. To demonstrate its potential use in comparatively complex information processing, we develop a precipitation-based iontronic synapse (PIS) capable of both potentiation and depression. Finally, we show that the postsynaptic signals from the multiple excitatory or inhibitory PISs can be integrated into the total "dendritic" current, which is a function of time and input history, as in actual hippocampal neural circuits.

Lyme disease is a tick-borne disease prevalent in North America, Europe, and Asia. Despite the accumulated knowledge from epidemiological, in vitro, and in animal studies, the understanding of dissemination of vector-borne pathogens, such as Borrelia burgdorferi (Bb), remains incomplete with several important knowledge gaps, especially related to invasion and intravasation into circulation. To elucidate the mechanistic details of these processes a tissue-engineered human dermal microvessel model is developed. Fluorescently labeled Bb are injected into the extracellular matrix (ECM) to mimic tick inoculation. High resolution, confocal imaging is performed to visualize the sub-acute phase of infection. From analysis of migration paths no evidence to support adhesin-mediated interactions between Bb and ECM components is found, suggesting that collagen fibers serve as inert obstacles to migration. Intravasation occurs at cell-cell junctions and is relatively fast, consistent with Bb swimming in ECM. In addition, it is found that Bb alone can induce endothelium activation, resulting in increased immune cell adhesion but no changes in global or local permeability. Together these results provide new insight into the minimum requirements for Bb dissemination and highlight how tissue-engineered models are complementary to animal models in visualizing dynamic processes associated with vector-borne pathogens., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

In vitro blood-brain barrier (BBB) models have played an important role in studying processes such as immune cell trafficking and drug delivery, as well as contributing to the understanding of mechanisms of disease progression. Many biological and pathological processes in the cerebrovasculature occur in capillaries and hence the lack of robust hierarchical models at the capillary scale is a major roadblock in BBB research. Here we report on a double-templating technique for engineering hierarchical BBB models with physiological barrier function at the capillary scale. We first demonstrate the formation of hierarchical vascular networks using human umbilical vein endothelial cells. We then characterize barrier function in a BBB model using brain microvascular endothelial-like cells (iBMECs) differentiated from induced pluripotent stem cells (iPSCs). Finally, we characterize immune cell adhesion and transmigration in response to perfusion with the inflammatory cytokine tumor necrosis factor-alpha, and show that we can recapitulate capillary-scale effects, such as leukocyte plugging, observed in mouse models. Our double-templated hierarchical model enables the study of a wide range of biological and pathological processes related to the human BBB., Competing Interests: Conflicts of Interest The authors declare no conflicts of interest.

In ionic liquids (ILs), the electric double layer (EDL) is where heterogeneous electron transfer (ET) occurs. Nevertheless, the relationship between the EDL structure and its kinetics has been rarely studied, especially for ET taking place in the inner Helmholtz plane (IHP). This is largely because of the lack of an appropriate model system for experiments. In this work, we determined the reorganization energy ( λ ) of Br 2 reduction in a redox-active IL 1-ethyl-1-methylpyrrolidinium polybromide (MEPBr 2 n +1 ) based on the Marcus-Hush-Chidsey model. Exceptionally fast mass transport of Br 2 in MEPBr 2 n +1 allows voltammograms to be obtained in which the current plateau is regulated by electron-transfer kinetics. This enables investigation of the microscopic environment in the IHP of the IL affecting electrocatalytic reactions through reorganization energy. As a demonstration, TiO 2 -modified Pt was employed to show pH-dependent reorganization energy, which suggests the switch of major ions at the IHP as a function of surface charges of electrodes., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Based on systematic electrochemical analysis, an integrated synthetic platform of C(sp 3 )-based organoboron compounds was established for the introduction of heteroatoms. The electrochemically mediated bond-forming strategy was shown to be highly effective for the functionalization of sp 3 -hybridized carbon atoms with significant steric hindrance. Moreover, virtually all the nonmetallic heteroatoms could be utilized as reaction partners using one unified protocol. The observed reactivity stems from the two consecutive single-electron oxidations of the substrate, which eventually generates an extremely reactive carbocation as the key intermediate. The detailed reaction profile could be elucidated through multifaceted electrochemical studies. Ultimately, a new dimension in the activation strategies for organoboron compounds was accomplished through the electrochemically driven reaction development.

Oxidative stress is a shared pathology of neurodegenerative disease and brain injuries, and is derived from perturbations to normal cell processes by aging or environmental factors such as UV exposure and air pollution. As oxidative cues are often present in systemic circulation, the blood-brain barrier (BBB) plays a key role in mediating the effect of these cues on brain dysfunction. Therefore, oxidative damage and disruption of the BBB is an emergent focus of neurodegenerative disease etiology and progression. We assessed barrier dysfunction in response to chronic and acute oxidative stress in 2D and 3D in vitro models of the BBB with human iPSC-derived brain microvascular endothelial-like cells (iBMECs). We first established doses of hydrogen peroxide to induce chronic damage (modeling aging and neurodegenerative disease) and acute damage (modeling the response to traumatic brain injury) by assessing barrier function via transendothelial electrical resistance in 2D iBMEC monolayers and permeability and monolayer integrity in 3D tissue-engineered iBMEC microvessels. Following application of these chronic and acute doses in our in vitro models, we found local, discrete structural changes were the most prevalent responses (rather than global barrier loss). Additionally, we validated unique functional changes in response to oxidative stress, including dysfunctional cell turnover dynamics and immune cell adhesion that were consistent with changes in gene expression., (© 2022. The Author(s).)

Surging interests in point-of-care diagnostics have led to the development of many lightweight and cost-effective paper-based sensors. Particularly, sensors using colorimetric readouts are considered highly advantageous because no additional detector or device is required for signal display. Herein, we introduce an electrochemically operated colorimetric sensor that can compensate for the disadvantages of traditional colorimetry, hence enhancing response time, reusability and color uniformity. On a single paper substrate, carbon/graphite paste was screen printed to form the working and counter electrodes, and Ag/AgCl ink was applied for the reference electrode. Prussian blue and Glucose oxidase were employed on the one of the carbon electrodes for the detection of analytes, hydrogen peroxide and glucose. For the colorimetric readout, indium tin oxide nanoparticles and polyaniline were consecutively introduced on the other carbon electrode, which is used as the counter electrode. The color change of electrochromic polyaniline could be clearly observed, and its application as a colorimetric sensor was demonstrated by the quantitative analyses of hydrogen peroxide and glucose. This paper-based electrochromic glucose sensor showed a short response time of 30 s and exhibited a detection limit of 126 μM for glucose. Along with its rapid and easy detection by incorporating the merits of electrochemical sensing and colorimetry, the paper-based electrochromic sensor could potentially contribute to the development of point-of-care devices by combination with portable power sources., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Photoelectrochemical (PEC) sensors are usually based on a single output signal, that is, the photocurrent change caused by the (photoelectro)chemical reaction between target analytes and photoelectrodes. However, the photocurrent may be influenced by redox species other than the target analyte; therefore, modifying the surface of photoelectrodes with probes that selectively bind to the analyte is essential. Moreover, even though various surface modification methods have been developed, distinguishing molecularly similar chemicals using PEC sensing systems remains a significant challenge. To address these selectivity issues, we proposed a photoanode-based PEC sensor that utilizes a cathodic transient current as a second output signal in addition to the photocurrent, which arises from the back reduction of photo-oxidized species. Factors influencing the back reduction were investigated by observing the transient photocurrent of hematite photoanodes in the presence of model redox probes. The chemical environment around the electrode-electrolyte interface was manipulated by altering the electrolyte composition or modifying the electrode surface. The favorable interaction between the electrode surface and redox species led to an increase in the extent of back reduction and the cathodic transient current. In addition, the extent of back reduction also depends on the chemical identity of the redox species, such as the kinetics of subsequent chemical reactions. Therefore, the synergistic combination of the photocurrent and the cathodic transient current enabled the differentiated detection of various catecholamine neurotransmitters with a single pristine photoelectrode, which has never been achieved using traditional PEC methods. Revisiting the transient photocurrent can complement conventional PEC applications and offers possibilities for more effective semiconductor-based applications.

It is important but challenging to elucidate the electrochemical reaction mechanisms of organic compounds using electroanalytical methods. Particularly, a rapid and straightforward method that provides information on reaction intermediates or other key electrochemical parameters may be useful. In this work, we exploited the advantages of classic thin-layer electrochemistry to develop a thin-layer electroanalysis microchip (TEAM). The TEAM provided better-resolved voltammetric peaks than under semi-infinite diffusion conditions owing to its small height. Importantly, rapid and accurate determination of the number of electrons transferred, n , was enabled by mechanically confining the microliter-scale volume analyte at the electrode, while securing ionic conduction using polyelectrolyte gels. The performance of the TEAM was validated using voltammetry and coulometry of standard redox couples. Utilizing the TEAM, a (spectro)electrochemical analysis of FM 1-43, an organic dye widely used in neuroscience, was successfully performed. Moreover, the TEAM was applied to study the electrochemical oxidation mechanism of pivanilides and alkyltrifluoroborate salts with different substituents and solvents. This work suggests that TEAM is a promising tool to provide invaluable mechanistic information and promote the rational design of electrosynthetic strategies.

The recent outbreak of COVID-19 has highlighted the seriousness of airborne diseases and the need for a proper pathogen detection system. Compared to the ample amount of research on biological detection, work on integrated devices for air monitoring is rare. In this work, we integrated a wet-cyclone air sampler and a DC impedance microfluidic cytometer to build a cyclone-cytometer integrated air monitor (CCAM). The wet-cyclone air sampler sucks the air and concentrates the bioaerosols into 10 mL of aqueous solvent. After 5 min of air sampling, the bioaerosol-containing solution was conveyed to the microfluidic cytometer for detection. The device was tested with aerosolized microbeads, dust, and Escherichia coli (E. coli). CCAM is shown to differentiate particles from 0.96 to 2.95 μm with high accuracy. The wet cyclone air-sampler showed a 28.04% sampling efficiency, and the DC impedance cytometer showed 87.68% detection efficiency, giving a total of 24.59% overall CCAM efficiency. After validation of the device performance, CCAM was used to detect bacterial aerosols and their viability without any separate pretreatment step. Differentiation of dust, live E. coli, and dead E. coli was successfully performed by the addition of BacLight bacterial viability reagent in the sampling solvent. The usage could be further extended to detection of specific species with proper antibody fluorescent label. A promising strategy for aerosol detection is proposed through the constructive integration of a DC impedance microfluidic cytometer and a wet-cyclone air sampler., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Electrochemistry of the silicon oxide dielectric layer, a notable insulator often used as a gate oxide, is counterintuitive, but addresses fundamental questions to yield novel scientific discoveries. In this minireview, the fundamental electron transfer mechanism of silicon oxide in the electrolyte solution is elucidated. The possible electrochemical reactions to date are discussed in detail, providing numerous potential areas of application which are elaborated and justified. This minireview not only provides background but also guides future research., (© 2021 Wiley-VCH GmbH.)

Photoelectrochemical cells represent one of the promising ways to renewably produce hydrogen (H 2 ) as a future chemical fuel. The design of a catalyst/semiconductor junction for the hydrogen evolution reaction (HER) requires various factors for high performance. In catalytic materials, an intrinsic activity with fast charge-transfer kinetics is important. Additionally, their thermodynamic property and physical adhesion should be compatible with the underlying semiconductor for favorable band alignment and stability during vigorous H 2 bubble formation. Moreover, catalysts, especially non-noble materials that demand a large amount of loading, should be adequately dispersed on the semiconductor surface to allow sufficient light absorption to generate excitons. One of the methods to simultaneously satisfy these conditions is to adopt an interfacial layer between the semiconductor and active materials in HER. The interfacial layer efficiently extracts the electrons from the semiconductor and conveys those to the catalytically active surface. We demonstrate Ag as a 3D interfacial nanostructure of patterned MoS x catalysts for photoelectrochemical HER. The nanostructured porous Ag layer was introduced by a simple chemical process, followed by photoelectrochemical deposition of MoS x to form MoS x /Ag nanostructures in cross-shaped catalyst pattern arrays. Ag modulated the surface electronic property of MoS x to improve the reaction kinetics as well as helped a charge transport at the Ag|p-Si(100) junction. The physically stable adhesion of catalysts was also achieved despite the ∼40 nm thick catalysts owing to the interfacial Ag nanostructure. This work contributes to further understand the complex multistep HER from light absorption to charge transfer to protons, helping to develop cost-effective and efficient photocathodes.

Low-cost catalysts with high activity and durability are necessary to achieve efficient large-scale energy conversion in photoelectrochemical cell (PEC) systems. An additional factor that governs the construction of photoelectrodes for PECs is the spatial control of the catalysts for efficient utilization of photogenerated charge carriers. Here, we demonstrate spatial decoupling of the light-absorbing and catalytic components in hierarchically structured Si-based photocathodes for the hydrogen evolution reaction (HER). By simply modifying a well-known metal-assisted chemical etching procedure, we fabricated a Si nanowire (NW) array-based photocathode with Ag-Pt catalysts at the base and small amounts of the Pt catalyst at the NW tips. This approach simultaneously mitigates the parasitic light absorption by the catalytic layers and recombination of charge carriers owing to the long transport distance, resulting in improved photoelectrochemical HER performance under simulated AM 1.5G illumination., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Catalyst-transfer polymerization has revolutionized the field of polymer synthesis due to its living character, but for a given catalyst system, the polymer scope is rather narrow. Herein we report a highly efficient Suzuki-Miyaura catalyst-transfer polymerization (SCTP) that covers a wide range of monomers from electron-rich (donor, D) to electron-deficient (acceptor, A) (hetero)arenes by rationally designing boronate monomers and using commercially available Buchwald RuPhos and SPhos Pd G3 precatalysts. Initially, we optimized the controlled polymerization of 3,4-propylenedioxythiophene (ProDOT), benzotriazole (BTz), quinoxaline (QX), and 2,3-diphenylquinoxaline (QXPh) by introducing new boronates, such as 4,4,8,8-tetramethyl-1,3,6,2-dioxazaborocane and its N -benzylated derivative, to modulate the reactivity and stability of the monomers. As a result, PProDOT, PBTz, PQX, and PQXPh were prepared with controlled molecular weight and narrow dispersity ( Đ < 1.29) in excellent yield (>85%). A detailed investigation of the polymer structures using 1 H NMR and MALDI-TOF spectrometry supported the chain-growth mechanism and the high initiation efficiency of the SCTP method. In addition, the use of RuPhos-Pd showing excellent catalyst-transfer ability on both D/A monomers led to unprecedented controlled D-A statistical copolymerization, thereby modulating the HOMO energy level (from -5.11 to -4.80 eV) and band gap energy (from 1.68 to 1.91 eV) of the resulting copolymers. Moreover, to demonstrate the living nature of SCTP, various combinations of D-A and A-A block copolymers (PBTz- b -PProDOT, PQX- b -PProDOT, and PQX- b -PBTz) were successfully prepared by the sequential addition method. Finally, simple but powerful one-shot D-A block copolymerization was achieved by maximizing the rate difference between a fast-propagating pinacol boronate donor and a slow-propagating acceptor to afford well-defined poly(3-hexylthiophene)- b -poly(benzotriazole).

Ion current rectification (ICR), diodelike behavior in surface-charged nanopores, shows promise in the design of delivery probes for manipulation of neural networks as it can solve diffusive leakages that might be critical in clinical and research applications. However, it has not been achieved because ICR has restrictions in nanosized dimension and low electrolyte concentration, and rectification direction is inappropriate for delivery. Herein, we present a polyelectrolyte gel-filled (PGF) micropipette harnessing inverted ICR as a delivery probe, which quantitatively transports glutamate to stimulate primary cultured neurons with high efficiency while minimizing leakages. Since the gel works as an ensemble of numerous surface-charged nanopores, the current is rectified in the micro-opening and physiological environment. By extending the charge-selective region using the gel, inverted ICR is generated, which drives outward deliveries of major charge carriers. This study will help in exploring new aspects of ICR and broaden its applications for advanced chemical delivery.

Coordination of synapses onto electrodes with high specificity and maintaining a stable and long-lasting interface have importance in the field of neural interfaces. One potential approach is to present ligands on the surface of electrodes that would be bound through a protein-protein interaction to specific areas of neuronal cells. Here, we functionalize electrode surfaces with genetically engineered neuroligin-1 protein and demonstrate the formation of a nascent presynaptic bouton upon binding to neurexin-1 β on the presynaptic membrane of neurons. The resulting synaptically connected electrode shows an assembly of presynaptic proteins and comparable exocytosis kinetics to that of native synapses. Importantly, a neuroligin-1-induced synapse-electrode interface exhibits type specificity and structural robustness. We envision that the use of synaptic adhesion proteins in modified neural electrodes may lead to new approaches in the interfacing of neural circuity and electronics.

Many human diseases are the result of abnormal expression or activation of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Not surprisingly, more than 30 tyrosine kinase inhibitors (TKIs) are currently in clinical use and provide unique treatment options for many patients. PTPs on the other hand have long been regarded as "undruggable" and only recently have gained increased attention in drug discovery. Striatal-enriched tyrosine phosphatase (STEP) is a neuron-specific PTP that is overactive in Alzheimer's disease (AD) and other neurodegenerative and neuropsychiatric disorders, including Parkinson's disease, schizophrenia, and fragile X syndrome. An emergent model suggests that the increase in STEP activity interferes with synaptic function and contributes to the characteristic cognitive and behavioral deficits present in these diseases. Prior efforts to generate STEP inhibitors with properties that warrant clinical development have largely failed. To identify novel STEP inhibitor scaffolds, we developed a biophysical, label-free high-throughput screening (HTS) platform based on the protein thermal shift (PTS) technology. In contrast to conventional HTS using STEP enzymatic assays, we found the PTS platform highly robust and capable of identifying true hits with confirmed STEP inhibitory activity and selectivity. This new platform promises to greatly advance STEP drug discovery and should be applicable to other PTP targets.

In response to the extensive utilization of ionic circuits, including in iontronics and wearable devices, a new method for fabricating a hydrogel-based ionic circuit on a polydimethylsiloxane (PDMS) microchip is reported. Prolonged UV/ozone oxidation combined with proper surface functionalizations and a novel microchip bonding method using thiol-epoxy click reaction enable the robust attachment of the photopolymerized hydrogel to the microchannel surface for eventual operation in electrolytes as an ionic circuit. The stretchable ionic diode constructed on the PDMS microchip shows a superior rectification ratio even under tensile stress and long-term storage stability. Furthermore, the combination of the ionic circuit and unique material properties of PDMS allows us to maximize the versatility and diversify the functionalities of the iontronic device, as demonstrated in a pressure-driven ionic switch and chip-integrated ionic regulator. Its iontronic signal transmission mimicking the excitatory and inhibitory synapses also evinces the potential of the hydrogel-based iontronics on the PDMS microchip as developed toward an aqueous neuromimetic information processor while opening up new opportunities for various bioinspired applications.

Animals digest food to fuel brain neurometabolism via cellular respiration. This study demonstrates the combination of a biofuel cell (BFC) and an animal brain stimulator (ABS) implanted in a pigeon. Glucose oxidation and oxygen reduction in an enzymatic BFC supplied electrical power to the ABS. Power from the BFC reached 0.12 mW in vitro and 0.08 mW in vivo using only the natural glucose and oxygen in the pigeon's body. A power management integrated circuit is used to harvest energy from the in vivo BFC at a rate of 28.4 mJ over 10 min, which is sufficient for intermittent neurostimulation., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The faradaic reaction at the insulator is counterintuitive. For this reason, electroorganic reactions at the dielectric layer have been scarcely investigated despite their interesting aspects and opportunities. In particular, the cathodic reaction at a silicon oxide surface under a negative potential bias remains unexplored. In this study, we utilize defective 200-nm-thick n + -Si/SiO 2 as a dielectric electrode for electrolysis in an H-type divided cell to demonstrate the cathodic electroorganic reaction of anthracene and its derivatives. Intriguingly, the oxidized products are generated at the cathode The experiments under various conditions provide consistent evidence supporting that the electrochemically generated hydrogen species, supposedly the hydrogen atom, is responsible for this phenomenon. The electrogenerated hydrogen species at the dielectric layer suggests a synthetic strategy for organic molecules., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

The breakdown of thin dielectric films (SiO 2 , Si 3 N 4 , HfO 2 ) immersed in aqueous electrolyte was investigated. The current and the kinetics of dielectric breakdown caused by large cathodic electric field applied across the dielectric layer reveal the electrochemical nature of dielectric materials. Electrolytes play a huge role in the established dielectric-electrolyte interface with respect to the overall electrical behavior of the system. Although aqueous cations are considered as spectator ions in most electrochemical systems, in dielectric interfaces the current-potential characteristics depend on the type of cation. Computer simulation based on density functional theory and molecular dynamics showed cations affect the dielectric strength. The responses of various dielectric films to solution components provide invaluable information for dielectric-incorporated electrochemical systems.

Color generation based on strategically designed plasmonic nanostructures is a promising approach for display applications with unprecedented high-resolution. However, it is disadvantageous in that the optical response is fixed once the structure is determined. Therefore, obtaining high modulation depth with reversible optical properties while maintaining its fixed nanostructure is a great challenge in nanophotonics. In this work, dynamic color tuning and switching using tungsten trioxide (WO 3 ), a representative electrochromic material, are demonstrated with reflection-type and transmission-type optical devices. Thin WO 3 films incorporated in simple stacked configurations undergo dynamic color change by the adjustment of their dielectric constant through the electrochromic principle. A large resonance wavelength shift up to 107 nm under an electrochemical bias of 3.2 V could be achieved by the reflection-type device. For the transmission-type device, on/off switchable color pixels with improved purity are demonstrated of which transmittance is modulated by up to 4.04:1.

As a novel approach to the in situ real-time investigation of an ITO electrode during the wet etching process, step-excitation Fourier-transform electrochemical impedance spectroscopy (FT-EIS) was implemented. The equivalent circuit parameters (e.g., R ct , C dl ) continuously obtained by the FT-EIS measurements during the entire etching process showed an electrode activation at the initial period as well as the completion of etching. The FT-EIS results were further validated by cyclic voltammograms and impedance measurements of partially etched ITO films using ferri- and ferrocyanide solution in combination with FESEM imaging, EDS, XRD analyses, and COMSOL simulation. We also demonstrated that this technique can be further utilized to obtain intact interdigitated array (IDA) electrodes in a reproducible manner, which is generally considered to be quite tricky due to delicacy of the pattern. Given that the FT-EIS allows for instantaneous snapshots of the electrode at every moment, this work may hold promise for in situ real-time examination of structural, electrokinetic, or mass transfer-related information on electrochemical systems undergoing constantly changing, transient processes including etching, which would be impossible with conventional electroanalytical techniques.

The detection of ions is of critical importance for environmental, industrial, and physiological applications, where sensitive and disposable ion sensing is still challenging. Herein, we present a sensitivity-tunable ion-sensing platform based on reverse electrodialysis, which is suitable for convenient and sensitive on-site analysis of various ions. It is revealed that this sensing system does not require any external power supply, and the sensitivities can be modulated by altering the number of stacks, possibly higher than the theoretical limitation, the Nernstian slope. The sensing system is integrated with a multicolor detection system via the introduction of polyaniline as a reporting material, which enables direct quantitative analysis based on a continuous color change gradient observable with the naked eye. Overall, the adopted approach by introducing reverse electrodialysis represents remarkable progress toward self-powered and disposable ion sensors with high and easily tunable potentiometric sensitivity.

Luminescent hexagonal dominant copper indium sulphide (h-dominant CIS) quantum dots (QDs) by precursor-injection of mixed metal-dialkyldithiocarbamate precursors. Owing to the different reactivity of the precursors, this method allowed the CIS QDs to grow while retaining the crystallinity of the hexagonal nucleus. The photoluminescence (PL) spectra exhibited dual emission (600-700 nm red emission and 700-800 nm NIR emission) resulting from the combined contributions of the hexagonal (wurtzite) h-CIS and tetragonal (chalcopyrite) t-CIS QDs, i.e. the NIR and red emissions were due to the h-CIS QDs and coexisting t-CIS QDs (weight ratio of h-CIS/t-CIS ~ 10), respectively. The PL intensities of the h-CIS as well as t-CIS QDs were enhanced by post-synthetic heat treatment; the t-CIS QDs were particularly sensitive to the heat treatment. By separating h-CIS and t-CIS successfully, it was demonstrated that this phenomenon was not affected by size and composition but by the donor-acceptor pair states and defect concentration originating from their crystal structure. The h-dominant CIS QDs in this work provide a new technique to control the optical property of Cu-In-S ternary NCs.

As biological signals are mainly based on ion transport, the differences in signal carriers have become a major issue for the intimate communication between electrical devices and biological areas. In this respect, an ionic device which can directly interpret ionic signals from biological systems needs to be designed. Particularly, it is also required to amplify the ionic signals for effective signal processing, since the amount of ions acquired from biological systems is very small. Here, we report the signal amplification in ionic systems as well as sensing through the modified design of polyelectrolyte hydrogel-based ionic diodes. By designing an open-junction structure, ionic signals from the external environment can be directly transmitted to an ionic diode. Moreover, the minute ionic signals injected into the devices can also be amplified to a large amount of ions. The signal transduction mechanism of the ion-to-ion amplification is suggested and clearly verified by revealing the generation of breakdown ionic currents during an ion injection. Subsequently, various methods for enhancing the amplification are suggested., Competing Interests: The authors declare no conflict of interest.

Over the recent years, the development of neural interface systems has stuck to using electrical cues to stimulate neurons and read out neural signals, although neurons relay signals via chemical release and recognition at synapses. In addition, conventional neural interfaces are vulnerable to cell migration and glial encapsulation due to the absence of connection anchoring the neuron into the device unlike synapses, which are firmly sustained by protein bonding. To close this discrepancy, we conducted an intensive investigation into the induced synapse interface by employing engineered synaptic proteins from a neural interface perspective. The strong potential of induced synaptic differentiation as an emerging neural interfacing technique is demonstrated by exploring its structural features, chemical release kinetics, robustness, and scalability to the brain tissue. We show that the exocytosis kinetics of induced synapses is similar to that of endogenous synapses. Moreover, induced synapses show remarkable stability, despite cell migration and growth. The synapse-inducing technique has broad applications to cultured hippocampal and cortex tissues and suggests a promising method to integrate neural circuits with digital elements.

Platinum is still the most active element for the hydrogen evolution reaction (HER); however, it suffers from its scarcity and high cost. Thus, significant efforts have been dedicated to maximize the catalytic activity with less loading. When Pt is utilized at a semiconductor surface, more factors have to be considered. Placing a catalyst directly in contact with a semiconductor supports the extraction of photogenerated minority carriers as well as boosts the catalytic reactions. In addition, a catalyst should be designed with prudence not to interfere in the light path with respect to absorption at the underlying substrate. Herein, we report the development of planar Si-based photocathodes, covered with a native oxide, for the HER, which also satisfy the prerequisites for the use of a three-dimensionally patterned, flower-like Ag-Pt catalyst. The catalyst consisted of nanoparticles of homogeneously alloyed Ag and Pt, fabricated by a galvanic exchange of Pt with Ag. Importantly, these two elements were proven to have their own functionalities. Ag not only contributed to transporting e- and Had to the Pt for subsequent processes of the HER but also effectively extracted minority carriers by diluting the high work function of Pt, leading to a better Schottky barrier at the catalyst-insulator-semiconductor junction. Furthermore, computational simulation revealed that the proposed catalyst pattern alleviated optical light loss with the increasing catalyst loading compared to the two-dimensional case. Owing to these effects, we could achieve 0.36 V (vs. reversible hydrogen electrode) as an open circuit potential and the near maximum current density of planar p-type Si. The findings in this work suggests deeper insights that could support the design of catalysts for solar-fuel systems.

This review encompasses the mechanisms of electrochemical glucose detection and recent advances in non-enzymatic glucose sensors based on a variety of materials ranging from platinum, gold, metal alloys/adatom, non-precious transition metal/metal oxides to glucose-specific organic materials. It shows that the discovery of new materials based on unique nanostructures have not only provided the detailed insight into non-enzymatic glucose oxidation, but also demonstrated the possibility of direct detection in whole blood or interstitial fluids. We critically evaluate various aspects of non-enzymatic electrochemical glucose sensors in terms of significance as well as performance. Beyond laboratory tests, the prospect of commercialization of non-enzymatic glucose sensors is discussed., (Copyright © 2018 Elsevier B.V. All rights reserved.)