The role of applied potential on particle sizing precision in single-entity blocking electrochemistry.

Blocking electrochemistry, a subfield of single-entity electrochemistry, enables in-situ sizing of redox-inactive particles. This method exploits the adsorptive impact of individual insulating particles on a microelectrode, which decreases the electrochemically active surface area of the electrode. Against the background of an electroactive redox reaction in solution, each individual impacting particle results in a discrete current drop, with the magnitude of the drop corresponding to the size of the blocking particle.

Size-Dependent Electrochemistry of Laser-Induced Graphene Electrodes.

Laser-induced graphene (LIG) electrodes have become popular for electrochemical sensor fabrication due to their simplicity for batch production without the use of reagents. The high surface area and favorable electrocatalytic properties also enable the design of small electrochemical devices while retaining the desired electrochemical performance. In this work, we systematically investigated the effect of LIG working electrode size, from 0.

Measurement of Neuropeptide Y in Aptamer-Modified Planar Electrodes.

Electrochemical impedance spectroscopy (EIS) is a powerful technique for studying the interaction at electrode/solution interfaces. The adoption of EIS for obtaining analytical signals in biosensors based on aptamers is gaining popularity because of its advantageous characteristics for molecular recognition. Neuropeptide Y (NPY), the most abundant neuropeptide in the body, plays a crucial role with its stress-relieving properties.

Quantifying picomoles of analyte from less than 100 live bacteria: A novel method with a buffering hydrogel as an electrochemical cell.

Microenvironmental changes in the chemical surrounding of bacterial cells might have a profound impact on the ecology of biofilms. However, quantifying total amount of picomoles of analyte from a miniscule number of bacteria is an analytical challenge. Here we provide a novel microliter volume hydrogel based electrochemical cell platform suitable of coulometrically measuring hydrogen peroxide (HO) produced by less than 100 cells of , a relevant member of the healthy oral microbiome.

Polarity reversal for enhanced electrochemical synthesis of HO over banana-peel derived biochar cathode for water remediation.

The fabrication of a cost-efficient cathode is critical for in-situ electrochemical generation of hydrogen peroxide (HO) to remove persistent organic pollutants from groundwater. Herein, we tested a stainless-steel (SS) mesh wrapped banana-peel derived biochar (BB) cathode for in-situ HO electrogeneration to degrade bromophenol blue (BPB) and Congo red (CR) dyes. Furthermore, polarity reversal is evaluated for the activation of BB surface via introduction of various oxygen containing functionalities that serve as active sites for the oxygen reduction reaction (ORR) to generate HO.

SARS-CoV-2 detection enabled by a portable and label-free photoelectrochemical genosensor using graphitic carbon nitride and gold nanoparticles.

Fast, sensitive, simple, and cheap sensors are highly desirable to be applied in the health system because they improve point-of-care diagnostics, which can reduce the number of cases of infection or even deaths. In this context, here we report the development of a label-free genosensor using a screen-printed electrode modified with 2D-carbonylated graphitic carbon nitride (CN), poly(diallyldimethylammonium) chloride (PDDA), and glutathione-protected gold nanoparticles (GSH-AuNPs) for photoelectrochemical (PEC) detection of SARS-CoV-2. We also made use of Arduino and 3D printing to miniaturize the sensor device.

Electrochemical Synthesis of HO for -nitrophenol Degradation Utilizing a Flow-through Three-dimensional Activated Carbon Cathode with Regeneration Capabilities.

The growing ubiquity of recalcitrant organic contaminants in the aqueous environment poses risks to effective and efficient water treatment and reuse. A novel three-dimensional (3D) electrochemical flow-through reactor employing activated carbon (AC) encased in a stainless-steel (SS) mesh as a cathode is proposed for the removal and degradation of a model recalcitrant contaminant -nitrophenol (PNP), a toxic compound that is not easily biodegradable or naturally photolyzed, can accumulate and lead to adverse environmental health outcomes, and is one of the more frequently detected pollutants in the environment. As a stable 3D electrode, granular AC supported by a SS mesh frame as a cathode is hypothesized to 1) electrogenerate HO via a 2-electron oxygen reduction reaction on the AC surface, 2) initiate decomposition of this electrogenerated HO to form hydroxyl radicals on catalytic sites of the AC surface 3) remove PNP molecules from the waste stream via adsorption, and 4) co-locate the PNP contaminant on the carbon surface to allow for oxidation by formed hydroxyl radicals.

Ultrasensitive electrochemical genosensors for species-specific diagnosis of malaria.

The absence of reliable species-specific diagnostic tools for malaria at point-of-care (POC) remains a major setback towards effective disease management. This is partly due to the limited sensitivity and specificity of the current malaria POC diagnostic kits especially in cases of low-density parasitaemia and mixed species infections. In this study, we describe the first label-free DNA-based genosensors based on electrochemical impedance spectroscopy (EIS) for species-specific detection of and .

Magnet-assisted electrochemical immunosensor based on surface-clean Pd-Au nanosheets for sensitive detection of SARS-CoV-2 spike protein.

Tracking and monitoring of low concentrations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can effectively control asymptomatic transmission of current coronavirus disease 2019 (COVID-19) in the early stages of infection. Here, we highlight an electrochemical immunosensor for sensitive detection of SARS-CoV-2 antigen marker spike protein. The surface-clean Pd-Au nanosheets as a substrate for efficient sensing and signal output have been synthesized.

PEDOT-AuNPs-based impedimetric immunosensor for the detection of SARS-CoV-2 antibodies.

Electrochemical sensors and biosensors are useful techniques for fast, inexpensive, sensitive, and easy detection of innumerous specimen. In face of COVID-19 pandemic, it became evident the necessity of a rapid and accurate diagnostic test, so the impedimetric immunosensor approach can be a good alternative to replace the conventional tests due to the specific antibody-antigen binding interaction and the fast response in comparison to traditional methods. In this work, a modified electrode with electrosynthesized PEDOT and gold nanoparticles followed by the immobilization of truncated nucleoprotein (N aa160-406aa) was used for a fast and reliable detection of antibodies against COVID-19 in human serum sample.

Molecularly imprinted polypyrrole based sensor for the detection of SARS-CoV-2 spike glycoprotein.

This study describes the application of a polypyrrole-based sensor for the determination of SARS-CoV-2-S spike glycoprotein. The SARS-CoV-2-S spike glycoprotein is a spike protein of the coronavirus SARS-CoV-2 that recently caused the worldwide spread of COVID-19 disease. This study is dedicated to the development of an electrochemical determination method based on the application of molecularly imprinted polymer technology.

Some fundamental insights into biological redox catalysis from the electrochemical characteristics of enzymes attached directly to electrodes.

This article outlines examples of where electrochemical investigations of electrocatalysis by proteins immobilised on an electrode reveal fundamental information about electron-proton coupling in catalysis and provide a new way to energise, control and observe multi-enzyme cascades.

Anodic Stripping Voltammetry on a Carbon-based Ion-Selective Electrode.

In this study, we demonstrated the unique capability of carbon-based ion-selective electrode (ISE) to perform highly sensitive square wave anodic stripping voltammetry, while maintaining all the properties of an ISE, in terms of sensitivity, detection limit, response time and selectivity. Square wave anodic stripping voltammetry involves deposition and dissolution steps of metal ions, which means adsorption and desorption of metal ions on the conductive ion-selective membrane without losing its ion-sensing property. To demonstrate this capability, we chose a Ca ion-selective microelectrode (μISE) as a potentiometric method and Cu-stripping voltammetry as an amperometric method.

Effect of iron oxide content and microstructural porosity on the performance of ceramic membranes as microbial fuel cell separators.

Ceramic materials based on naturally occurring clays are a low cost and environmentally friendly alternative to commercial polymer-based membranes in bioelectrochemical systems. In this work, ceramic membranes containing different amounts of iron oxide (1.06, 2.

Electrochemical Reduction and Oxidation of Eight Unnatural 2'-Deoxynucleosides at a Pyrolytic Graphite Electrode.

Recently we showed the reduction and oxidation of six natural 2'-deoxynucleosides in the presence of the ambient oxygen using the very broad potential window of a pyrolytic graphite electrode (PGE). Using the same procedure, 2'-deoxynucleoside analogs (dNs) that are parts of an artificially expanded genetic information system (AEGIS) were analyzed. Seven of the eight tested AEGIS dNs provided specific signals (voltammetric redox peaks).

Thin layer cell behavior of CNT yarn and cavity carbon nanopipette electrodes: Effect on catecholamine detection.

Carbon nanotube yarn microelectrodes (CNTYMEs) are an alternative to carbon-fiber microelectrodes (CFMEs) with interesting electrochemical properties because analyte is momentarily trapped in cavities between the CNTs. Here, we compare fast-scan cyclic voltammetry (FSCV) detection of catecholamines, including dopamine, norepinephrine, and epinephrine, at CNTYMEs, CFMEs, as well as cavity carbon nanopipette electrodes (CNPEs). At CFMEs, current decreases dramatically at high FSCV repetition frequencies.

Air-breathing cathode self-powered supercapacitive microbial fuel cell with human urine as electrolyte.

In this work, a membraneless microbial fuel cell (MFC) with an empty volume of 1.5 mL, fed continuously with hydrolysed urine, was tested in supercapacitive mode (SC-MFC). In order to enhance the power output, a double strategy was used: i) a double cathode was added leading to a decrease in the equivalent series resistance (ESR); ii) the apparent capacitance was boosted up by adding capacitive features on the anode electrode.

A new method for urine electrofiltration and long term power enhancement using surface modified anodes with activated carbon in ceramic microbial fuel cells.

This work is presenting for the first time the use of inexpensive and efficient anode material for boosting power production, as well as improving electrofiltration of human urine in tubular microbial fuel cells (MFCs). The MFCs were constructed using unglazed ceramic clay functioning as the membrane and chassis. The study is looking into effective anodic surface modification by applying activated carbon micro-nanostructure onto carbon fibres that allows electrode packing without excessive enlargement of the electrode.

Study of TiO/Ti4O photo-anodes inserted in an activated carbon packed bed cathode: Towards the development of 3D-type photo-electro-Fenton reactors for water treatment.

In this work, commercially available Polymethyl-meta-acrylate (PMMA) spectroscopy cells were modified on the external walls with films of TiO, TiO or TiO/TiO mixtures. Film characterization was carried out using SEM and UV-vis spectroscopy. The results of photocatalytic (PC), electro-oxidation (EO), and photoelectrochemical (PEC) experiments on the decolorization of a methyl orange (MO) model dye solution showed that while anatase provides better photocatalytic properties and the partially reduced TiO larger electronic conductivity, the TiO/TiO composite film behaves as a semiconductor substrate that combines the advantages of both materials (for PEC experiments for instance, decolorization values for the model dye solution using TiO, TiO and a TiO/TiO mixed film, corresponded to 35%, 46% and 53%, respectively).

Unveiling salinity effects on photo-bioelectrocatalysis through combination of bioinformatics and electrochemistry.

Little is known about the adaptation strategies utilized by photosynthetic microorganisms to cope with salinity changes happening in the environment, and the effects on microbial electrochemical technologies. Herein, bioinformatics analysis revealed a metabolism shift in resulting from salt stress, with changes in gene expression allowing accumulation of compatible solutes to balance osmotic pressure, together with the up-regulation of the nitrogen fixation cycle, an electron sink of the photosynthetic electron transfer chain. Using the transcriptome evidence of hindered electron transfer in the photosynthetic electron transport chain induced by adaption to salinity, increased understanding of photo-bioelectrocatalysis under salt stress is achieved.

Electrochemical cell lysis of gram-positive and gram-negative bacteria: DNA extraction from environmental water samples.

Cell lysis is an essential step for the nucleic acid-based surveillance of bacteriological water quality. Recently, electrochemical cell lysis (ECL), which is based on the local generation of hydroxide at a cathode surface, has been reported to be a rapid and reagent-free method for cell lysis. Herein, we describe the development of a milliliter-output ECL device and its performance characterization with respect to the DNA extraction efficiency for gram-negative bacteria ( and Typhi) and gram-positive bacteria ( and ).

Bottom-up Cu filling of annular through silicon vias: Microstructure and texture.

Microstructural and morphological evolution during bottom-up Cu filling of annular through silicon vias (TSV) in a CuSO-HSO-Cl-poloxamine electrolyte is examined. Deposition proceeds in two distinct stages beginning with a passive-to-active state transition on the via sidewalls whose depth and ultimate thickness depends on the polymer flux. Growth is conformal or tapered with columnar grains whose width and texture differ between the outer and inner sidewalls of the annulus due to area reduction and expansion respectively.

A core-shell structured CoMoO•nHO@CoFeOOH nanocatalyst for electrochemical evolution of oxygen.

Nickel-iron oxyhydroxide (NiFeOOH) is well recognized as the best-performing oxygen evolution reaction (OER) catalyst in alkaline electrolytes, however its analogue cobalt-iron oxyhydroxide (CoFeOOH) is surprisingly less explored despite their structural similarity. Inspired by our recent study on high-performance HER catalyst using the nanostructured CoMoO•nHO precursor, herein, we report a facile synthesis of CoFeOOH catalyst derived from the same precursor and its excellent electrocatalytic properties towards the OER in alkaline electrolytes. A core-shell structured nanocatalyst consisting of disordered CoFeOOH layer over the surface of crystalline CoMoO•nHO nanosheets was synthesized using a simple hydrothermal method followed by anodic electrooxidation.

Self-stratified and self-powered micro-supercapacitor integrated into a microbial fuel cell operating in human urine.

A self-stratified microbial fuel cell fed with human urine with a total internal volume of 0.55 ml was investigated as an internal supercapacitor, for the first time. The internal self-stratification allowed the development of two zones within the cell volume.