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In this article, poly(1,2‐diaminoanthraquinone) (pDAAQ) and poly(1,5‐diaminonaphthalene) (pDAN) were electrochemically deposited layer by layer on a glassy carbon electrode (GCE) to generate pDAAQ/pDAN@GCE and pDAN/pDAAQ@GCE composite electrodes, respectively. The morphology and characteristics of the modified electrodes were investigated via electrochemical impedance spectroscopy)EIS), Fourier transform infrared spectroscopy (FT‐IR), and scanning electron microscopy)SEM). The obtained results reveal the outstanding performance of the pDAN/pDAAQ@GCE electrode for electrochemical nitrite sensing where pDAAQ plays a vital role as the inner layer. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV) measurements revealed that the oxidation peak current of nitrite was proportional to its concentration. The best LSV results were obtained in a concentration range of 10–150 μM, with a limit of detection of 1.2 μM. Furthermore, the pDAN/pDAAQ@GCE composite electrode was used to determine nitrite ions in real water samples with good results. [ABSTRACT FROM AUTHOR]

A nanosecond pulsed fiber laser was used to modify the surface of 304 stainless steel. The compactness, microstructure, chemical composition, and corrosion resistance of the stainless steel passive film were observed by the blue dot detection method, scanning electron microscopy, x‐ray photoelectron spectroscopy, and electrochemical methods. The influence of different laser fluences on the stability and corrosion resistance of the stainless steel passive film was studied. The results show that with increasing laser fluence, the discoloration reaction time of the stainless steel surface increases first and then decreases, while the surface roughness decreases first and then increases. When the laser fluence is lower than 11.19 J/cm2, a compact and uniform passive film is formed. When the laser fluence is larger than this value, the stainless steel substrate is prone to secondary corrosion. Chromium oxides are enriched in the passive film, and the anodic dissolution rate decreases, which promotes a positive shift in the corrosion potential of the stainless steel, decreases the corrosion current density and increases the polarization resistance and the corrosion resistance. The surface corrosion resistance is thus significantly improved. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Cosmetic Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The challenges associated to oxygen reduction reaction (ORR) electrocatalysis are undoubtedly the most intricate impediments to solve regarding fuel cell vehicle (FCV) commercialization, mainly due to the complexity of this reaction and the scarcity of the required electrocatalysts. The synthesis of non-precious electrocatalysts with high intrinsic selectivity is indeed crucial in this field, but the methodology utilized to come to selectivity conclusions is undeniably equally important. In this work, we demonstrate how the higher required electrode loadings of a Fe-N-MWCNT catalyst in a rotating ring disc electrode (RRDE) prevent access to all of the peroxide produced by the catalyst during ORR. Via a spraying technique, much smaller amounts of the same catalyst were deposited on a flat boron-doped diamond (BDD) and their loading was determined meticulously by atomic force microscopy (AFM). These ultra-low loadings were investigated using scanning electrochemical microscopy (SECM), which revealed higher peroxide production and lower selectivity. This finding may have crucial implications for future ORR investigations in the laboratory, considering the harmful effect peroxide has on the catalyst.

The effect of carbon onions or onionlike carbons (OLCs) as a dopant on the supercapacitive properties of titanium carbide MXene (Ti2C) has been studied. The materials were characterized using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and electrochemical techniques, including cyclic voltammetry, constant current charge/discharge, and electrochemical impedance spectroscopy. It was found that the introduction of OLCs into the layered MXene structure increases the long-term cycling stability of the material from ∼80% to >95%. It was also found to increase the supercapacitance of MXene in the 5% quantity from ca. 104 to 148 F/g but decreased the supercapacitance in the 10% quantity from ca. 104 to 92 F/g. The power and energy density improved in the 5% OLC-doped sample compared to the pristine sample for current densities between 0.5 and 5 A/g. Overall, this study showcased the unique ability of OLCs to improve the electrochemical performance of a Ti2C-based supercapacitor. [ABSTRACT FROM AUTHOR]

For the reliable safety assessment of repositories of highly radioactive waste, further development of the modelling of radionuclide migration and transfer in the environment is necessary, which requires a deeper process understanding at the molecular level. Eu(III) is a non-radioactive analogue for trivalent actinides, which contribute heavily to radiotoxicity in a repository. For in-depth study of the interaction of plants with trivalent f elements, we investigated the uptake, speciation, and localization of Eu(III) in Brassica napus plants at two concentrations, 30 and 200 µM, as a function of the incubation time up to 72 h. Eu(III) was used as luminescence probe for combined microscopy and chemical speciation analyses of it in Brassica napus plants. The localization of bioassociated Eu(III) in plant parts was explored by spatially resolved chemical microscopy. Three Eu(III) species were identified in the root tissue. Moreover, different luminescence spectroscopic techniques were applied for an improved Eu(III) species determination in solution. In addition, transmission electron microscopy combined with energy-dispersive X-ray spectroscopy was used to localize Eu(III) in the plant tissue, showing Eu-containing aggregates. By using this multi-method setup, a profound knowledge on the behavior of Eu(III) within plants and changes in its speciation could be obtained, showing that different Eu(III) species occur simultaneously within the root tissue and in solution.

Several in-situ electrochemical approaches have been developed for performing a localized photoelectrochemical investigation of the photoanode. One of the techniques is scanning electrochemical microscopy (SECM), which probes local heterogeneous reaction kinetics and fluxes of generated species. In traditional SECM analysis of photocatalysts, evaluation of the influence of radiation on the rate of studied reaction requires an additional dark background experiment. Here, using SECM and an inverted optical microscope, we demonstrate the determination of O2 flux caused by light-driven photoelectrocatalytic water splitting. Photocatalytic signal and dark background are recorded in a single SECM image. We used an indium tin oxide electrode modified with hematite (α-Fe2O3) by electrodeposition as a model sample. The light-driven flux of oxygen is calculated by analysis of SECM image recorded in substrate generation/tip collection mode. In photoelectrochemistry, the qualitative and quantitative knowledge of oxygen evolution will open new doors for understanding the local effects of dopants and hole scavengers in a straightforward and conventional manner. [ABSTRACT FROM AUTHOR]

A challenging task is to promote Ru atom economy and simultaneously alleviate Ru dissolution during the hydrogen evolution reaction (HER) process. Herein, Ru nanograins (≈1.7 nm in size) uniformly grown on 1T‐MoS2 lace‐decorated Ti3C2Tx MXene sheets (Ru@1T‐MoS2‐MXene) are successfully synthesized with three types of interfaces (Ru/MoS2, Ru/MXene, and MoS2/MXene). It gives high mass activity of 0.79 mA µgRu−1 at an overpotential of 100 mV, which is ≈36 times that of Ru NPs. It also has a much smaller Ru dissolution rate (9 ng h−1), accounting for 22% of the rate for Ru NPs. Electrochemical tests, scanning electrochemical microscopy measurements combined with DFT calculations disclose the role of triple interface optimization in improved activity and stability. First, 2D MoS2 and MXene can well disperse and stabilize Ru grains, giving larger electrochemical active area. Then, Ru/MoS2 interfaces weakening H* adsorption energy and Ru/MXene interfaces enhancing electrical conductivity, can efficiently improve the activity. Next, MoS2/MXene interfaces can protect MXene sheet edges from oxidation and keep 1T‐MoS2 phase stability during the long‐term catalytic process. Meanwhile, Ru@1T‐MoS2‐MXene also displays superior activity and stability in neutral and alkaline media. This work provides a multiple‐interface optimization route to develop high‐efficiency and durable pH‐universal Ru‐based HER electrocatalysts. [ABSTRACT FROM AUTHOR]

In the present world, the high energy demand rapidly depletes existing fossil fuel reserves, urging the necessity to harvest energy from clean and renewable resources. In this study, the use of a triboelectric nanogenerator (TENG) is shown beyond the conventional practice of use in self‐powered electronics, to the production of green hydrogen from renewable mechanical energy. For the first time the use of a magnetic covalent organic framework composite as positive triboelectric material for a contact‐separation mode TENG (CS‐TENG) in which MXene incorporated polydimethylsiloxane (PDMS) film serves as negative triboelectric material, is demonstrated. A facile way of incorporating micropatterns on the surface of PDMS/MXene film is shown utilizing the advantages of 3D printing technology. The CS‐TENG harvests energy from simple mechanical actions such as human handclapping and toe‐tapping. The energy from such low‐scale mechanical actions is applied for water electrolysis. Scanning electrochemical microscopy is employed to confirm the evolution of hydrogen and oxygen by the harvested electrical energy from mechanical actions. This research is expected to pave the way for producing green hydrogen anywhere, by utilizing the mechanical energy from nature such as raindrops, wind, and the movement of vehicles. [ABSTRACT FROM AUTHOR]

Lithium metal is one of the most promising anode materials for lithium-ion batteries; however, lithium dendrite growth hinders its large-scale development. So far, the dendrite formation mechanism is unclear. Herein, the dynamic evolution of lithium deposition in etheryl-based and ethylene carbonate (EC)-based electrolytes was obtained by combining an in situ electrochemical atomic force microscope (EC-AFM) with an electrochemical workstation. Three growth modes of lithium particles are proposed: preferential, merged, and independent growth. In addition, a lithium deposition schematic is proposed to clearly describe the morphological changes in lithium deposition. This schematic shows the process of lithium deposition, thus providing a theoretical basis for solving the problem of lithium dendrite growth. [ABSTRACT FROM AUTHOR]

Carbon‐based nanomaterials are renowned for their exceptional properties, making them propitious candidates for oxygen reduction reaction (ORR) electrocatalysis. However, their intrinsic activity is often challenging to investigate unambiguously with conventional methodologies due to the inherent complexities of such systems and the material itself. Zooming into the material and gaining electrochemical information with high resolution is a way to get rid of many experimental factors that influence the catalytic activity in macro‐scale measurements. Herein, we employ nano‐scale scanning electrochemical cell microscopy (SECCM) to investigate individual catalyst agglomerates with and without Nafion content. The intrinsic ORR activity of the catalyst was unravelled by using a unique approach of normalizing the data of all measured points by their distinctive electrochemical surface area (ECSA). When coupling with scanning electron microscopy (SEM), the structure and morphology of the catalytically active agglomerates were visualized. [ABSTRACT FROM AUTHOR]

Fingerprints have long been the gold standard for personal identification in forensic science. However, realizing the high-resolution enhancement of eccrine LFPs is difficult using the traditional methods and the label-free detection of fingerprint residue information is also challenging. Herein, we propose two enhancement strategies for LFPs on PVDF membrane (LFPs/PVDF) using blue-black ink staining and scanning electrochemical microscopy (SECM). The blue-black ink staining method was used for the first time to develop three types (sebaceous, natural and eccrine) of LFPs/PVDF based on the difference in wettability between the fingerprint residues and PVDF membrane. The enhanced fingerprints clearly displayed levels 1–3 features with high contrast and low background interference. Furthermore, we achieved chemical imaging of the LFP/PVDF samples, where their possible visualization mechanisms were ascribed to the electrochemical reactivity of squalene and difference in wettability between the LFP and PVDF membrane, which was first proposed and investigated by SECM imaging and water contact angle (WCA) measurements, respectively. Significantly, SECM imaging not only provided fingerprint patterns without any labelling but also revealed the spatial distribution information of squalene in LFPs simultaneously. In addition, it was also demonstrated that LFPs deposited on various surfaces were first successfully transferred to the PVDF membrane, and then further developed with both methods, making them general for personal identity-related applications. Taken together, the blue-black ink staining method can easily and quickly obtain level 3 features of LFPs/PVDF and the SECM approach can non-invasively image the topography and chemical information of LFPs/PVDF, and thus they can be potentially selected according to various requirements in forensic scenarios. [ABSTRACT FROM AUTHOR]

This review article outlines the set of observations and findings from some previous publications that addressed the different techniques used for understanding and evaluating metallic corrosion and its retardation by using different inhibitors. The main emphasis is on the different electrochemical characterization techniques and surface analysis methods used for studying corrosion inhibition. A brief about polarization, electrochemical noise, electrochemical frequency modulation, impedance study for electrochemical characterization techniques and contact angle, scanning electrochemical microscopy, atomic force microscopy, and scanning electron microscopy methods, x-ray photoelectron spectroscopy, etc. are included for a better understanding of corrosion inhibition phenomenon. The literature suggests that corrosion of metals and alloys is effectively controlled by the use of inhibitors having heteroatoms such as nitrogen, oxygen, or sulfur. In this article, the papers from the last sixteen years i.e., from 1996 to 2021 are considered to get an insight into current methods for retarding corrosion. General introduction, mechanisms of corrosion along with factors affecting corrosion has also been described in the present article. Data collected in this review will be advantageous for researchers to get an idea about the basics and the recent techniques used in corrosion study. [ABSTRACT FROM AUTHOR]

Myocardial fibrosis progression and imbalanced redox state are closely associated with increased extracellular matrix (ECM) stiffness. Candesartan (CAN), an angiotensin II (Ang II) receptor inhibitor, has shown promising anti-fibrosis and antioxidant efficacy in previous cardiovascular disease studies. However, the effect of ECM stiffness on CAN efficacy remains elusive. In this study, we constructed rat models with three different degrees of myocardial fibrosis and treated them with CAN, and then characterized the stiffness, cardiac function, and NADPH oxidase-2 (NOX2) expression of the myocardial tissues. Based on the obtained stiffness of myocardial tissues, we used polyacrylamide (PA) gels with three different stiffness to mimic the ECM stiffness of cardiac fibroblasts (CFs) at the early, middle, and late stages of myocardial fibrosis as the cell culture substrates and then constructed CFs mechanical microenvironment models. We studied the effects of PA gel stiffness on the migration, proliferation, and activation of CFs without and with CAN treatment, and characterized the reactive oxygen species (ROS) and glutathione (GSH) levels of CFs using fluorometry and scanning electrochemical microscopy (SECM). We found that CAN has the best amelioration efficacy in the cardiac function and NOX2 levels in rats with medium-stiffness myocardial tissue, and the most obvious anti-fibrosis and antioxidant efficacy in CFs on the medium-stiffness PA gels. Our work proves the effect of ECM stiffness on CAN efficacy in myocardial anti-fibrosis and antioxidants for the first time, and the results demonstrate that the effect of ECM stiffness on drug efficacy should also be considered in the treatment of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

In the present study, the microstructure and mechanical properties of Ti-xTa (x = 5%, 15%, and 25% wt. Ta) alloys produced by using an induced furnace by the cold crucible levitation fusion technique were investigated and compared. The microstructure was examined by scanning electron microscopy and X-ray diffraction. The alloys present a microstructure characterized by the α′ lamellar structure in a matrix of the transformed β phase. From the bulk materials, the samples for the tensile tests were prepared and based on the results and the elastic modulus was calculated by deducting the lowest values for the Ti-25Ta alloy. Moreover, a surface alkali treatment functionalization was performed using 10 M NaOH. The microstructure of the new developed films on the surface of the Ti-xTa alloys was investigated by scanning electron microscopy and the chemical analysis revealed the formation of sodium titanate and sodium tantanate along with titanium and tantalum oxides. Using low loads, the Vickers hardness test revealed increased hardness values for the alkali-treated samples. After exposure to simulated body fluid, phosphorus and calcium were identified on the surface of the new developed film, indicating the development of apatite. The corrosion resistance was evaluated by open cell potential measurements in simulated body fluid before and after NaOH treatment. The tests were performed at 22 °C as well as at 40 °C, simulating fever. The results show that the Ta content has a detrimental effect on the investigated alloys' microstructure, hardness, elastic modulus, and corrosion behavior. [ABSTRACT FROM AUTHOR]

Isopropylmethylphenols, namely thymol and carvacrol, are natural phenolic monoterpenoids with a wide spectrum of bioactivity making them applicable in the cosmetic, pharmaceutical, and food industry. The dose-dependent antioxidant properties of isopropylmethylphenols require their quantification in real samples. Glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and electropolymerized thymolphthalein has been developed for the sensitive quantification of isopropylmethylphenols. Conditions of thymolphthalein electropolymerization (monomer concentration, number of cycles, and electrolysis parameters) providing the best response to thymol have been found. Scanning electron microscopy and electrochemical methods confirm the effectivity of the electrode developed. The linear dynamic ranges of 0.050–25 and 25–100 µM for thymol and 0.10–10 and 10–100 µM for carvacrol with detection limits of 0.037 and 0.063 µM, respectively, have been achieved in differential pulse mode in Britton–Robinson buffer pH 2.0. The selectivity of the isopropylmethylphenols response in the presence of typical interferences (inorganic ions, saccharides, ascorbic acid) and other phenolics (caffeic, chlorogenic, gallic and rosmarinic acids, and quercetin) is a significant advantage over other electrochemical methods. The electrode has been used in the analysis of oregano and thyme spices. Total isopropylmethylphenols contents have been evaluated after a single sonication-assisted extraction with methanol. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) is considered as one of the most promising non‐noble‐metal catalysts for hydrogen evolution reaction (HER). To achieve practical application, introducing sulfur (S) vacancies on the inert basal plane of MoS2 is a widely accepted strategy to improve its HER activity. However, probing active sites at the nanoscale and quantitatively analyzing the related electrocatalytic activity in electrolyte aqueous solution are still great challenges. In this work, utilizing high‐resolution scanning electrochemical microscopy, optimized electrodes and newly designed thermal drift calibration software, the HER activity of the S vacancies on an MoS2 inert surface is in situ imaged with less than 20‐nm‐radius sensitivity and the HER kinetic data for S vacancies, including Tafel plot and onset potential, are quantitatively measured. Additionally, the stability of S vacancies over the wide range of pH 0−13 is investigated. This study provides a viable strategy for obtaining the catalytic kinetics of nanoscale active sites on structurally complex electrocatalysts and evaluating the stability of defects in different environments for 2D material‐based catalysts. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The electrocatalytic activity for the oxygen evolution reaction in alkaline electrolyte of hexagonal spinel Co3O4 nanoparticles derived using scanning electrochemical cell microscopy (SECCM) is correlated with scanning electron microscopy and atomic force microscopy images of the droplet landing sites. A unique way to deconvolute the intrinsic catalytic activity of individual crystal facets of the hexagonal Co3O4 spinel particle is demonstrated in terms of the turnover frequency (TOF) of surface Co atoms. The top surface exposing 111 crystal planes displayed a thickness‐dependent TOF with a TOF of about 100 s−1 at a potential of 1.8 V vs. RHE and a particle thickness of 100 nm. The edge of the particle exposing (110) planes, however, showed an average TOF of 270±68 s−1 at 1.8 V vs. RHE and no correlation with particle thickness. The higher atomic density of Co atoms on the edge surface (2.5 times of the top) renders the overall catalytic activity of the edge planes significantly higher than that of the top planes. The use of a free‐diffusing Os complex in the alkaline electrolyte revealed the low electrical conductivity through individual particles, which explains the thickness‐dependent TOF of the top planes and could be a reason for the low activity of the top (111) planes. [ABSTRACT FROM AUTHOR]

Anatase TiO2 is a promising material for Li‐ion (Li+) batteries with fast charging capability. However, Li+ (de)intercalation dynamics in TiO2 remain elusive and reported diffusivities span many orders of magnitude. Here, we develop a smart protocol for scanning electrochemical cell microscopy (SECCM) with in situ optical microscopy (OM) to enable the high‐throughput charge/discharge analysis of single TiO2 nanoparticle clusters. Directly probing active nanoparticles revealed that TiO2 with a size of ≈50 nm can store over 30 % of the theoretical capacity at an extremely fast charge/discharge rate of ≈100 C. This finding of fast Li+ storage in TiO2 particles strengthens its potential for fast‐charging batteries. More generally, smart SECCM‐OM should find wide applications for high‐throughput electrochemical screening of nanostructured materials. [ABSTRACT FROM AUTHOR]

Simple Summary: 3D bioprinting has been shown to be an extremely useful method for the fabrication of in vitro tridimensional cellular models which better resemble the structural and functional complexity of real tissues. The cell microenvironment is a crucial determinant of cell behavior and its recreation in cellular in vitro models is fundamental to performing reliable biomedical and biotechnological experimentations. In this work, we employed extrusion 3D bioprinting using a bioink containing HeLa cells to build a model of a cervical tumor; the resulting HeLa spheroids were described in terms of their dimensions and expression of membrane proteins involved in cell adhesion. A key cellular feature of the microenvironment—the oxygen concentration within HeLa spheroids—was determined by scanning electrochemical microscopy with a micrometric spatial resolution using platinum nanoelectrodes. Scanning electrochemical microscopy was also employed to study the diffusion of a molecule in the biofabricated cervical tumor construct, as a model of drug diffusion in the 3D architecture. Current cancer research is limited by the availability of reliable in vivo and in vitro models that are able to reproduce the fundamental hallmarks of cancer. Animal experimentation is of paramount importance in the progress of research, but it is becoming more evident that it has several limitations due to the numerous differences between animal tissues and real, in vivo human tissues. 3D bioprinting techniques have become an attractive tool for many basic and applied research fields. Concerning cancer, this technology has enabled the development of three-dimensional in vitro tumor models that recreate the characteristics of real tissues and look extremely promising for studying cancer cell biology. As 3D bioprinting is a relatively recently developed technique, there is still a lack of characterization of the chemical cellular microenvironment of 3D bioprinted constructs. In this work, we fabricated a cervical tumor model obtained by 3D bioprinting of HeLa cells in an alginate-based matrix. Characterization of the spheroid population obtained as a function of culturing time was performed by phase-contrast and confocal fluorescence microscopies. Scanning electrochemical microscopy and platinum nanoelectrodes were employed to characterize oxygen concentrations—a fundamental characteristic of the cellular microenvironment—with a high spatial resolution within the 3D bioprinted cervical tumor model; we also demonstrated that the diffusion of a molecular model of drugs in the 3D bioprinted construct, in which the spheroids were embedded, could be measured quantitatively over time using scanning electrochemical microscopy. [ABSTRACT FROM AUTHOR]

This review centers on a closed bipolar electrode (BPE) array using an electro‐fluorochromism (EFC) or electro‐chemiluminescence (ECL) reaction as the reporting reaction. Electrochemical signals at one pole of the closed BPE array can be transduced into the EFC or ECL signals at the opposite pole. Therefore, the current signal of a redox reaction can be easily detected and imaged by monitoring the luminescence signal. Recent developments in closed BPE array‐based EFC and ECL sensing and imaging are summarized and discussed in detail. Finally, we consider the challenges and opportunities for improving the spatial resolution of closed BPE array‐based electrochemical imaging, and emphasize the important application of this technique to the imaging of cellular activities at the single‐cell level. [ABSTRACT FROM AUTHOR]

Interfacial carrier transfer kinetics is critical to the efficiency and stability of perovskite solar cells. Herein, we measure the regeneration rate constant, absorption cross-section, reduction rate constant, and conductivity of hole transport layered perovskites using scanning electrochemical microscopy (SECM). The SECM feedback revealed that the regeneration rate constant, absorption cross-section, and reduction rate constant of the nickel oxide (NiO) layer perovskite layer are higher than those of the poly (3,4-ethyenedioxythiophene)-poly (styrenesulfonate) layered perovskite. Also, at a specific flux density ( J h v ), the value of the regeneration rate constant (keff) in both blue and red illuminations for the NiO/CH3NH3PbI3 film is significantly higher than in both PEDOT: PSS/CH3NH3PbI3 and FTO/CH3NH3PbI3 films. The difference in keff between layered and nonlayered perovskite conforms to the impact of the hole conducting layer on the charge transfer kinetics. According to the findings, SECM is a powerful approach for screening an appropriate hole transport layer for stable perovskite solar cells. [ABSTRACT FROM AUTHOR]

A novel nanocomposite consisting of polyurethane (PU), poly(o-phenylenediamine) (PoPD), and silicon carbide (SiC) nanoparticles was investigated for its application in marine environment through electrochemical techniques. The PoPD/SiC nanofillers were characterized by TGA, XRD, SEM/EDX, and TEM analyses. The anticorrosion and mechanical properties of different coating formulation in marine environment were evaluated by electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM). It was also found that the coating resistance of PU-PoPD/SiC nanocomposite was over 41 times higher than that of the PU coating. The PU-PoPD/SiC coatings on the brass showed low current of 1.9 I/nA due to copper dissolution and 6.8 I/nA due to zinc dissolution because of the well distribution of PoPD/SiC nanofiller in PU coating. The analyses of the resultant degradation products by SEM/EDX and XRD techniques confirmed the presence of Si which has a major role in protecting the brass surface against corrosion. Results showed that the PU composite with 2 wt.% PoPD/SiC hybrid nanofillers had outstanding coating performance. This nanocomposite demonstrated improved corrosion protection. As a result, the developed PU-PoPD/SiC nanocomposite has exceptional adhesion strength and anticorrosion properties and might be exploited to develop next-generation anticorrosive coatings. [ABSTRACT FROM AUTHOR]

Nanoconfinement in mesoporous nanoarchitectures could dramatically change molecular transport and reaction kinetics during electrochemical process. A molecular‐level understanding of nanoconfinement and mass transport is critical for the applications, but a proper route to study it is lacking. Herein, we develop a single nanoreactor electrochemiluminescence (SNECL) microscopy based on Ru(bpy)32+‐loaded mesoporous silica nanoparticle to directly visualize in situ nanoconfinement‐enhanced electrochemical reactions at the single molecule level. Meanwhile, mass transport capability of single nanoreactor, reflected as long decay time and recovery ability, is monitored and simulated with a high spatial resolution. The nanoconfinement effects in our system also enable imaging single proteins on cellular membrane. Our SNECL approach may pave the way to decipher the nanoconfinement effects during electrochemical process, and build bridges between mesoporous nanoarchitectures and potential electrochemical applications. [ABSTRACT FROM AUTHOR]

A 7 kWh automotive battery module with 396 interconnected cells was tested with electrochemical impedance spectroscopy (EIS) and time‐domain pulsing over 260 charge‐discharge cycles. An EIS calibration workflow was developed for low complex impedance values in a frequency range of 1 kHz to 50 mHz. Significant corrections on the resistance and the reactance were obtained from the calibration, particularly at frequencies above 100 Hz. Equivalent circuit parameters were extracted from the EIS spectra and the pulse response and investigated with respect to the cycle number and state‐of‐charge (SoC). Fit parameters were robustly extracted including Rsol, Rct, and L from EIS, and R0, τ1 and τ2 from time‐domain pulsing. The ohmic resistance decreased over the cycling number indicating an enhanced wetting of the electrodes. Charge transfer resistance Rct showed a monotonic increase over the cycles related to cell ageing. From the charge and discharge pulses, the ohmic resistance R0 was determined from the instantaneous voltage step of the recovery pulse, while the two time constants τ1 and τ2 correspond to the slower exponential recovery phase. R0 from the time‐domain showed a similar trend as Rsol plus a contribution of Rct from EIS. Overall, we show that calibrated EIS and time‐domain pulsing are efficient methods to gain insights into the electrochemical processes related to different SoCs and the cycling ageing of battery modules and packs. [ABSTRACT FROM AUTHOR]

The fundamental process in non‐aqueous redox flow battery (NRFB) operation revolves around electron transfer (ET) between a current collector electrode and redox‐active organic molecules (redoxmers) in solution. Here, we present an approach utilizing scanning electrochemical microscopy (SECM) to evaluate interfacial ET kinetics between redoxmers and various electrode materials of interest at desired locations. This spot‐analysis method relies on the measurement of heterogeneous electron transfer rate constants (kf or kb) as a function of applied potential (E−E0′). As demonstrated by COMSOL simulations, this method enables the quantification of Butler‐Volmer kinetic parameters, the standard heterogeneous rate constant, k0, and the transfer coefficient, α. Our method enabled the identification of inherent asymmetries in the ET kinetics arising during the reduction of ferrocene‐based redoxmers, compared to their oxidation which displayed faster rate constants. Similar behavior was observed on a wide variety of carbon electrodes such as multi‐layer graphene, highly ordered pyrolytic graphite, glassy carbon, and chemical vapor deposition‐grown graphite films. However, aqueous systems and Pt do not exhibit such kinetic effects. Our analysis suggests that differential adsorption of the redoxmers is insufficient to account for our observations. Displaying a greater versatility than conventional electroanalytical methods, we demonstrate the operation of our spot analysis at concentrations up to 100 mM of redoxmer over graphite films. Looking forward, our method can be used to assess non‐idealities in a variety of redoxmer/electrode/solvent systems with quantitative evaluation of kinetics for applications in redox‐flow battery research. [ABSTRACT FROM AUTHOR]

Miniaturized paper‐based electrochemical sensors were fabricated using kraft paper and CO2 laser, dispensing the need for chemical reagents and controlled atmospheric conditions. This study initially evaluated the paper type and laser processing parameters, enhancing the electrodes′ robustness, electrochemical response, and electrical resistance. The sensors were also treated by applying −1 V for 60 s in 1.0 mol L−1 KCl, which is a simple and rapid procedure. The electrochemical treatment increased the electroactive area and roughness, confirmed by scanning electron microscopy. These aspects helped modulate the sensors′ electrochemical response for nitrite determination, improving selectivity and sensitivity for this compound. The sensors also showed repeatability and batch‐to‐batch reproducibility, with 2.2 and 10 % RSD, respectively. Therefore, this work brings a protocol to fabricating competitive electrochemical sensors through a sustainable strategy, opening possibilities for designing new analytical systems. [ABSTRACT FROM AUTHOR]

Polymer blends are important for both commercial utility and scientific understanding. The degree of interfacial mixing in polymer blends is important since it influences the blends' mechanical properties. Understanding bulk properties in multiphase polymeric materials requires knowledge of the interfacial properties of the materials. The characterization of the interface, in terms of its width and composition profile, provides insight about the bulk behaviour of the material. Chemical microscopy through electron energy‐loss spectroscopy (EELS) in a transmission electron microscope is gaining popularity to characterize narrow polymer–polymer interfaces. In this work, we show how scanning transmission electron microscopy spectrum imaging, a spatially resolved energy‐loss spectroscopy, can be employed to calculate the interfacial width in a pair of immiscible polymers, taking a polycarbonate–polystyrene (PC‐PS) bilayer as an example. By mapping peaks unique to each of the blend constituents at several points across the interface, we show how the interfacial profile concentrations can be determined. With this method we calculated the interfacial width in the PC‐PS bilayer sample to be approximately 32 nm, even utilizing low resolution spectrometers, which are more widely available. Using the technique described with higher resolution EELS instruments having a better signal‐to‐noise ratio, a higher spatial resolution can be achieved. Using EELS chemical fingerprints of polymers that have been developed earlier, the technique presented here has the potential for effective visualization and morphological measurements of phase‐differentiated polymer blends. This paper is an attempt to enable a new user to characterize polymer–polymer interfaces using chemical microscopy. © 2022 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Biofuel production has increased significantly in several countries in recent decades. Different evaluation techniques are required for their characterization. The study measures the properties of the obtained biodiesel and a commercial diesel sample, using the techniques of open circuit potential, linear scanning voltammetry and electrochemical impedance spectroscopy. The transesterification reaction between sunflower oil and methanol was carried out with ultrasound as the energy source. The determination of triglyceride conversion to biodiesel is performed by high performance liquid chromatography (HPLC), obtaining up to 99.79% with a yield of 93.40% at a transesterification temperature of 50 ∘ C for 60 min with a methanol/oil molar ratio of 6:1. The potassium hydroxide catalyst concentration was 1.0 g catalyst/100 g oil. The biodiesel samples generally showed open circuit potential (OCP) values less than 790 mV and stabilization time less than 120 s, Linear sweep voltammograms (LSV) show no reaction peaks with current densities on the order of NanoAmpere, Electrochemical impedance spectroscopy (EIS) showed a capacitive system with impedances on the order of MΩ cm 2 at low frequency; This information could help characterize biofuels and other similar materials. [ABSTRACT FROM AUTHOR]

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Chemical imaging of corrosion processes involving copper species using scanning electrochemical microscopy has been hampered by the lack of soluble oxidation states for copper that can be achieved by amperometric conversion at the tip. Indeed, the only possibility is to reduce the corrosion products at the tip, thus modifying the chemical response of the electrode material and requiring subsequent redissolution of the copper deposits. Consequently, the limitations arising from the system prevented a full-scale quantification, requiring the development of new methodologies or the optimisation of those currently available, as we pursued with the present work. Therefore, the voltammetric behaviours of gold macro- and microelectrodes were evaluated with respect to the collection and redissolution of Cu2+ ions, with the aim of using them as sensing probes in scanning electrochemical microscopy (SECM) to investigate the activity of copper surfaces in acidic chloride-containing environments. Cyclic and square-wave voltammetric techniques were explored for copper collection and subsequent stripping on Au microelectrode tips in SECM with the objective to capture in situ image electrochemical reactivity distributions across copper surfaces undergoing corrosion.

Microbial hybrid photosynthesis has attracted great interests in recent years since it integrates the advantages of natural and artificial photosynthesis for solar‐to‐chemical conversion. Coupling a light source with scanning electrochemical microscopy, scanning photoelectrochemical microscopy (SPECM) shows great potential in investigating the interfacial reactions of microbial hybrid photosynthesis. In this Emerging Topic, the potential roles of SPECM in revealing biotic–abiotic interfacial electron transfer mechanisms and calculating electrode process kinetics are proposed for hybrid photosynthesis, and this will also inspire the applications of SPECM in the fields including biomineralization, photocatalytic‐biodegradation and microbial photoelectrochemical systems. [ABSTRACT FROM AUTHOR]

The purpose of this work is to develop a bioanode using the enzymes of glucose oxidase (GOx) and alcohol dehydrogenase (ADH) as catalysts to oxidised glucose and alcohol present in different beverages. The study was carried out using the covalent bonding method for both enzymes via the functionalization of carbon nanofibers for the formation of carboxyl groups that can form bonds with the amine groups of the enzyme, as well as using tetrabutylammonium bromide (TBAB) with Nafion. The optimum operation parameters of both enzymes (pH and temperature) were determined for the later evaluation in a microfluidic fuel cell. In addition, using the scanning electrochemical microscopy technique, a local study of enzymatic processes is used to demonstrate that the enzymes immobilized on the same electrode remain active. The evaluation of the microfluidic fuel cell was carried out using different solutions, 0.01 M glucose, 0.01 M ethanol and a mixture of 0.01 M glucose and 0.01 M ethanol, all in phosphate buffer solutions at pH 7, where it was possible to obtain a maximum performance of 5.07 ± 0.1 mW cm−2, and there was a significant increase in current density compared to non-composite solutions (glucose or ethanol). In addition, different alcoholic beverages were used to evaluate the versatility and adaptability of the bi-enzymatic anode electrode with the perspective use in Lab-on-a-Chip systems. [ABSTRACT FROM AUTHOR]

Voltammetry of immobilized particles (VIMP) and scanning electrochemical microscopy techniques are combined to study nanosamples from 60 Apulian red‐figured pottery objects from six Apulian archaeological sites (Altamura, Arpi, Conversano, Egnazia, Monte Sannace, Taranto) and three Attic samples from Pella. The VIMP signatures corresponding to the electrocatalytic effect of microparticulate deposits of the clay body and the black gloss on the oxygen evolution reaction and the oxygen reduction reaction are obtained. These signatures provide information on the reducing/oxidizing conditions of firing. The combination of the above voltammetric data permits us to distinguish between Apulian production and Attic importations as well as to discriminate the productions from different archaeological sites or even within different technologies in samples from the same site. [ABSTRACT FROM AUTHOR]

An efficient immobilization of Glucose oxidase (GOx) on an appropriate substrate is one of the main challenges of developing fuel cells that allow energy to be obtained from renewable substrates such as carbohydrates in physiological environments. The research importance of biofuel cells relies on their experimental robustness and high compatibility with biological organisms such as tissues or the bloodstream with the aim of obtaining electrical energy even from living systems. In this work, we report the use of 5,10,15,20 tetrakis (1-methyl-4-pyridinium) porphyrin and glutathione capped CdTe Quantum dots (GSH-CdTeQD) as a support matrix for the immobilization of GOx on carbon surfaces. Fluorescent GSH-CdTeQD particles were synthesized and their characterization by UV-Vis spectrophotometry showed a particle size between 5–7 nm, which was confirmed by DLS and TEM measurements. Graphite and Toray paper electrodes were modified by a drop coating of porphyrin, GSH-CdTeQD and GOx, and their electrochemical activity toward glucose oxidation was evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Additionally, GOx modified electrode activity was explored by scanning electrochemical microscopy, finding that near to 70% of the surface was covered with active enzyme. The modified electrodes showed a glucose sensitivity of 0.58 ± 0.01 μA/mM and an apparent Michaelis constant of 7.8 mM. The addition of BSA blocking protein maintained the current response of common interferent molecules such as ascorbic acid (AA) with less than a 5% of interference percentage. Finally, the complex electrodes were employed as anodes in a microfluidic biofuel cell (μBFC) in order to evaluate the performance in energy production. The enzymatic anodes used in the μBFC allowed us to obtain a current density of 7.53 mAcm−2 at the maximum power density of 2.30 mWcm−2; an open circuit potential of 0.57 V was observed in the biofuel cell. The results obtained suggest that the support matrix porphyrin and GSH-CdTeQD is appropriate to immobilize GOx while preserving the enzyme's catalytic activity. The reported electrode arrangement is a viable option for bioenergy production and/or glucose quantification. [ABSTRACT FROM AUTHOR]

The toxicity of propachlor (PROP) with its chloroacetanilide members is reported. Rapid and sensitive detection of PROP is critical for ecotoxicity evaluation and the removal process. A novel voltammetric sensor is developed based on imprinted poly (o-phenylene diamine-co-pyrrole) (o-PD-co-Py) and electrochemically reduced graphene oxide (ERGO) to detect PROP at a trace level. The use of ERGO provides a high density of imprinted cavities for better sensitivity. The imprinted layer of poly (o-PD-co-Py) improves the selectivity of the sensor. The electrode modification was characterized by scanning electron microscopy and electrochemical approaches. The working parameters of the sensor were investigated and optimized. The redox behavior of an external probe of [Fe(CN)6]3−/4− was recorded as the sensor signal for PROP selective binding. The proposed sensor presented wide linear responses to logarithmic PROP concentrations from 0.1 pM to 0.1 µM with a LOD of 0.08 pM. The sensor's selectivity against some interference was demonstrated. This sensor was applied successfully to detect PROP in spiked water (lake and tap), red tea, and soil samples with good recoveries and reasonable RSD % values. [ABSTRACT FROM AUTHOR]

Scanning electrochemical microscopy (SECM), which makes it possible to acquire the information on both the topography and local electrochemical properties of a surface, is a type of probe microscopy technique. Due to the abundance of the developed techniques, SECM makes it possible to solve a broad spectrum of problems on studying the electroactive properties of materials. SECM is of special interest for the studies in the field of energy accumulators and, in particular, lithium-ion batteries (LIBs). Recent advances in the study of accumulators have shown that the electrochemical properties demonstrated by materials at a macrolevel are substantially different at the microlevel. Due to their high spatial resolution, SECM methods give unique information about the processes occurring in LIBs at the micro- and nanoscales. This review is an introduction to the broad SECM sphere and is focused on the basic operational principles and examples of applications in the study of energy accumulators. [ABSTRACT FROM AUTHOR]

Monitoring pH changes at the micro/nano scale is essential to gain a fundamental understanding of surface processes. Detection of local pH changes at the electrode/electrolyte interface can be achieved through the use of micro-/nano-sized pH sensors. When combined with scanning electrochemical microscopy (SECM), these sensors can provide measurements with high spatial resolution. This article reviews the state-of-the-art design and fabrication of micro-/nano-sized pH sensors, as well as their applications based on SECM. Considerations for selecting sensing probes for use in biological studies, corrosion science, in energy applications, and for environmental research are examined. Different types of pH sensitive probes are summarized and compared. Finally, future trends and emerging applications of micro-/nano-sized pH sensors are discussed. [ABSTRACT FROM AUTHOR]

The structure and properties of the positive active material PbO2 are key factors affecting the performance of lead–acid batteries. To improve the cycle life and specific capacity of lead–acid batteries, a chitosan (CS)‐modified PbO2–CS–F cathode material is prepared by electrodeposition in a lead methanesulfonate system. The microstructure and phase composition are characterized by scanning electron microscopy and X‐ray diffraction. The electrochemical activity of the cathode material is analyzed by cyclic voltammetry, linear sweep voltammograms, electrochemical impedance spectroscopy, and scanning electrochemical microscopy. The battery performance of laboratory lead–acid batteries assembled with the cathode material is analyzed by a battery tester. The results show that the PbO2–CS–F cathode material has the smallest grain size (21.879 nm), the highest oxygen evolution potential (2.237 V), and the highest exchange current density (3.788 × 10−7 A cm−2), smallest charge transfer resistance (5.359 Ω cm2), and highest chemical activity in the series of PbO2 cathode materials. The laboratory lead–acid battery assembled from PbO2–CS–F cathode material exhibist the best battery performance, with the first discharge capacities of 4257 mAh and the discharge‐specific capacity after 500 cycles is 196 mAh g−1. [ABSTRACT FROM AUTHOR]

Over the last 30 years, scanning electrochemical microscopy (SECM) has become a fundamental technique in corrosion research. With its high spatial resolution and its ability to study local electrochemistry, it contributes essentially to the understanding of corrosion processes. By using selective micro- and nano-sensors, concentration profiles of different corrosion relevant species, from protons to metal ions, can be established. This review provides a comprehensive overview about SECM based techniques and discusses various types of microsensors, including materials selection and preparation techniques, and it provides extensive tables on redox-couples for specific corrosion research applications. [ABSTRACT FROM AUTHOR]

Central nervous system is sensitive and vulnerable to heat. Oxidative state and oxidative damage of neurons under heat stress are vital for understanding early consequences and mechanisms of heat‐related neuronal injury, which remains elusive partly due to the technical challenge of in situ and quantitative monitoring methods. Herein, a temperature‐controlled scanning electrochemical microscopy (SECM) platform with programmable pulse potential and depth scan modes is developed for in situ and quantitatively monitoring of oxygen consumption, extracellular hydrogen peroxide level, and cell membrane permeability of neurons under thermal microenvironment of 37–42 °C. The SECM results show that neuronal oxygen consumption reaches a maximum at 40 °C and then decreases, extracellular H2O2 level increases from 39 °C, and membrane permeability increases from 2.0 ± 0.6 × 10−5 to 7.2 ± 0.8 × 10−5 m s−1 from 39 to 42 °C. The therapeutic effect on oxidative damage of neurons under hyperthermia conditions (40–42 °C) is further evaluated by SECM and fluorescence methods, which can be partially alleviated by the potent antioxidant edaravone. This work realizes in situ and quantitatively observing the heat‐induced oxidative state and oxidative damage of living neurons using SECM for the first time, which results can contribute to a better understanding of the heat‐related cellular injury mechanism. [ABSTRACT FROM AUTHOR]

The study of corrosion of magnesium and its alloys has emerged a hot topic in the applications of lightweight structural materials. The inherently high electrochemical activity of bare magnesium surfaces still lacks a convincing mechanism to describe the observed experimental characteristics, and it has prompted the development of various types of protective coatings with the aim of slowing metal dissolution. In recent years, new instruments and techniques have been developed to study with spatial resolution the local corrosion processes that occur in metallic materials in general, and for magnesium and its alloys in particular, both for bare surfaces and coated. Scanning microelectrochemical techniques, such as local electrochemical impedance spectroscopy (LEIS), scanning electrochemical microscopy (SECM), scanning vibrating electrode technique (SVET), scanning ion-selective electrode technique (SIET) and scanning Kelvin probe (SKP) can provide information about the local electrochemical activity of metallic surfaces. In the present work, the applications of these techniques in corrosion studies of magnesium and its alloys are reviewed. Assessment of corrosion mechanisms, barrier properties of conventional coatings and active corrosion behavior of self-healing coatings are examined. Limitations and future developments in this area are discussed. [ABSTRACT FROM AUTHOR]

The corrosion behavior and mechanism of 13Cr stainless steel in the solution with 1 mol/L NaCl and 5 mmol/L KI were investigated by weight loss method, scanning electrochemical microscopy (SECM), the phase analysis (XRD) of inclusions, and surface analysis technique (SEM and EDS). Results showed that the corrosion rate was a linear relationship with the time and Cl− concentration. The corrosion became serious with the increase in time and Cl− concentration. The corrosion occurred in the unstable electroactive points that contained aluminum oxide and metallic phase inclusions. The generation and disappearance of the electroactive points simultaneously occurred with the corrosion. The active dissolved level on different areas of the surface of 13Cr stainless-steel sample was different. The oxidation current peak of the sample presented the strip shape. The corrosion dissolution was mainly caused by aluminum oxide inclusions (Al2O3) and FeAl phase. [ABSTRACT FROM AUTHOR]

Nanocomposite coatings have been extensively used in the manufacture of automotive components to protect against corrosion of steel structures. The (3-mercaptopropyl) tris[2-(2-methoxyethoxy) ethoxy] silane (MPTMEES) functionalized Cr3C2 was encapsulated with graphene oxide (GO) as an efficient nanofiller in the epoxy matrix (EP). The silanized chromium carbide wrapped in graphene oxide was tested by SEM/EDX and TGA. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) were used to study the protective performance of epoxy coating on steel in the presence of varying weight percentages of graphene oxide wrapped silanized chromium carbide in seawater. After 1 h of immersion, the coating resistance of EP-MPTMEES/Cr3C2 was determined to be over 43% higher than that of pure matrix. After 240 h in seawater, EIS tests revealed that EP-GO/MPTMEES-Cr3C2 nanocomposite coatings had a higher coating resistance (6340 kΩ.cm2) than ordinary epoxy (1.2 kΩ.cm2) coatings. Because of the coated substrate's improved resistance to anodic dissipation, the least dissipation of ferrous ions was found at the crack of the EP-GO/MPTMEES-Cr3C2 nanocomposite coated steel specimen (1.5 I/nA). The silanized Cr3C2 was reinforced in the degradation products, forming an excellent passive layer at the coating/steel contact, according to FE-SEM/EDX analysis. The newly developed EP-GO/MPTMEES-Cr3C2 nanocomposite coating had improved corrosion protection and enhanced hydrophobic characteristics (WCA: 146°), according to the findings. The epoxy matrix with graphene oxide wrapped silanized chromium carbide demonstrated improved adhesive capabilities. [ABSTRACT FROM AUTHOR]

In the bottom ash (BA) of municipal solid waste incineration, the content of iron and aluminum is relatively high. The efficiency of eddy current extraction of non-ferrous metals (including aluminium) routinely used in incineration plants is limited. The determination of the form of occurrence of aluminium or aluminium-rich components in BA is important in terms of its recovery or utilisation. BA from a newly built incineration plant in Poland was analysed using chemical analysis, X-ray diffraction, optical microscopy, and scanning electron microscopy with chemical microanalysis. Samples of water-quenched BA were analysed. For comparison, a non-quenched sample (collected above a water tank) was analysed. The obtained results indicate that aluminium-rich components in BA are present in both the melt phase and quench phase. In the melt phase (glassy material), the content of aluminium is low (usually below 2 wt%). Aluminium-rich components present in glass, inherited after aluminium products are usually oxidised, and occur as platy or irregular forms. Aluminium components in the quench phase are significantly transformed with the common presence of Cl− and SO42− phases formed during reaction with the quench water. Secondary phases form simple or complex rims around metallic or slightly oxidised cores, of which the size is significantly reduced during transformations. The variety in the forms of aluminium occurrence in BA makes its recovery challenging and inefficient. The reduced content of metallic aluminium indicates that the potential for hydrogen generation of BA is low. [ABSTRACT FROM AUTHOR]

Although the high incidence and recurrence rates of urothelial cancer of the bladder (UCB) are heavy burdens, a noninvasive tool for effectively detecting UCB as an alternative to voided urine cytology, which has low sensitivity, is yet to be reported. Herein, we propose an intelligent discrimination method between normal (SV-HUC-1) and cancerous (TCCSUP) urothelial cells by using a combination of micro-dimensional electrochemical impedance spectroscopy (µEIS) with machine learning (ML) for a noninvasive and high-accuracy UCB diagnostic tool. We developed a unique valved flow cytometry, equipped with a pneumatic valve to increase sensitivity without cell clogging. Since contact between a cell and electrodes is tight with a high volume fraction, the electric field can be effectively confined to the cell. This enables the proposed sensor to highly discriminate different cell types at frequencies of 10, 50, 100, 500 kHz, and 1 MHz. A total of 236 impedance spectra were applied to six ML models, and systematic comparisons of the ML models were carried out. The hyperparameters were estimated by conducting a grid search or Bayesian optimization. Among the ML models, random forest strongly discriminated between SV-HUC-1 and TCCSUP, with an accuracy of 91.7%, sensitivity of 92.9%, precision of 92.9%, specificity of 90%, and F1-score of 93.8%. [ABSTRACT FROM AUTHOR]

Bacterial biofilm, a highly structured community with developmental processes from cell adherence to highly dense biofilms, is of critical concern in many industries. Investigations of parameters mediating biofilm formation, interactions between bacterial species, and parameters governing biofilm stability are quite important for understanding mechanism of biofilm formation. Scanning electrochemical microscopy (SECM), a local electrochemical technique using a microelectrode as its probe, can monitor microbe interactions in situ via detection of small molecules or biochemical cues with spatial and temporal resolution. In this review, we summarize the recent advances in biofilm research using SECM. First, we introduce the applications and potential biochemical cues of biofilms. Then, we classify the applications based on the bacterial species of interest, focusing on SECM to study key biochemical cues and highlighting underlying metabolic processes involved in biofilm formation. Finally, we discuss the challenges and limitations given the complexity and diversity of biofilms for future SECM studies. [ABSTRACT FROM AUTHOR]