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This study presents the combination of electrochemical cell based biosensor and fluorescence microscopy on a single platform to track biomolecular processes contributing to the morphology changes of the cells. Initial experiments demonstrate that using interdigitated electrodes where the gold microfingers were comparable in width and spacing to a single cell have the optimal sensitivity in the final electrochemical cell based‐sensing device. This was determined by measuring the cell index, based on the impedance analysis of bare and cell‐covered microelectrodes. The fabrication of the electrodes on a glass substrate enabled the capture of high‐resolution fluorescence microscopy images of single cells and related intracellular calcium release inside the HeLa cells via a window incorporated into the gold microelectrode design. As an illustration of the enhanced capability of the combined approach over traditional impedance cellular assay, the opto‐electric assay was utilized as a functional readout for G protein couple receptor activation. The simultaneous examinations of cells stimulated with histamine demonstrated an association between time courses of changes in cytosolic calcium concentration and reductions in cell‐cell adhesions. [ABSTRACT FROM AUTHOR]

Herein is explored a dual optical and electrical cell based biosensor that can provide insights into cellular events. The fabrication steps along with the electrical characterization of the microelectrodes is described. Initial experiments show that the ability of indium tin oxide (ITO) to detect biological cells at the electrode‐cell layer interface mainly depends on the size of sensing area. Following this, the impact of conductivity was also explored to assess the real time impedance signal during the adhesion of a non‐confluent layer of the cells on different substrates. Electrodes with a higher conductivity than ITO gave much higher senstivity of impedance changes which allowed the dynamics of subtle cellular morphology changes to be monitored at densities far lower than a confluent layer of cells. Finally, the capability of ITO and gold microelectrode as a functional readout for G protein couple receptor activation were determined. These set of analyses highlighted the challenges and opportunities of ITO substrate as a dual cell‐based assay for quantitative analysis of subtle changes in cell morphology. [ABSTRACT FROM AUTHOR]

Geneva), Johan Bobacka (Åbo Akademi Univ.), Philippe Bühlmann (Univ. Minnesota), Daniel Citterio (Keio Univ.), Justin Gooding (Univ. With much anticipation after a one-year delay caused by the COVID-19 pandemic, the Mátrafüred International Conference on Electrochemical Sensors was held June 12-17, 2022, in Visegrád, Hungary. Serge Lemay (Univ. Twente), Peter Lieberzeit (Univ. Vienna), Tom Lindfors (Åbo Akademi Univ.), Daniel Mandler (Hebrew Univ. Jerusalem), Agata Michalska (Univ. Warsaw), Karin Mölling (Univ. Zürich), Frieder Scheller (Univ. Potsdam), Joseph Wang (Univ. California San Diego). [Extracted from the article]

Gold-coated magnetic nanoparticles (Au@MNPs) have attracted significant interest in electrochemistry in recent years. This is especially the case with their application as dispersible electrodes where modified Au@MNPs are dispersed into a solution, selectively bind to the analyte of interest and are then brought to an electrode via application of a magnetic field for measurement. This paper characterizes four types of Au@MNPs with different sizes, shapes, and method of synthesis as dispersible electrodes. The Au@MNPs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy and scanning electron microscopy. In addition, the electrochemical behaviour of Au@MNPs was investigated using cyclic voltammetry. The four sorts of Au@MNPs were evaluated with regards to the three main features required in the dispersible electrodes approach, well-defined morphology, well-defined electrochemistry and fast response to a magnetic field. The Cubic-Au@MNPs, which presents the simplest synthetic route, showed the best electrochemical stability and performance, responding quickly to a magnet and had a well defined shape. [ABSTRACT FROM AUTHOR]

The influence of graphene on the electrical communication through organic layers fabricated on graphite and gold electrodes is investigated. These layers were prepared by in situ reductive adsorption of 4-aminobenzoic acid in the presence of NaNO2 and HCl to have surface bound carboxylic acid functionalities, followed by covalent attachment of 1-aminopyrene via an amide coupling reaction to have surface bound pyrene groups for graphene immobilization via noncovalent ππ stacking interaction. The coverage of the layers created via reductive adsorption on graphite electrodes was found to be much higher than that on gold electrodes. It was revealed that graphene significantly enhances the electrical communication through the layers on graphite electrodes but on gold electrodes the enhancement effect through the layers was only minor. However, when gold electrodes were modified with a self-assembled monolayer (SAM) of propanethiol the subsequent immobilization of graphene resulted in a significant enhancement of the electrical communication. It is also found that immobilization of graphene could affect the electron transfer between the redox probe, pyrene and the underlying electrodes. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to characterize the graphene sheets. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) were also used to characterize the stepwise modified electrodes. [ABSTRACT FROM AUTHOR]

An amperometric immunosensor for glycosylated hemoglobin (HbA1c) is reported. A glassy carbon electrode is modified with gold nanoparticles (AuNPs) bearing a ferrocene derivative and a glycosylated pentapeptide (GPP) as an epitope to which anti-HbA1c IgG can selectively bind. The rest of the electrode is passivated with an oligo(ethylene oxide) species to give the electrode resistant to nonspecific adsorption of proteins. Complexation of anti-HbA1c IgG with the surface bound epitope resulted in attenuation of the ferrocene electrochemistry. The immunosensor can detect HbA1c in the range of 4.6 %-15.1 % of total hemoglobin in human blood by a competitive inhibition assay. [ABSTRACT FROM AUTHOR]