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MXene, a family of two-dimensional (2D) transition metal carbides and nitrides, has intriguing electrochemical energy storage and electrocatalysis applications. Introducing the electronic metal-support interaction (EMSI) effect is one effective strategy to optimize the catalytic efficiency for MXene-based composites. However, most of the studies concentrate on optimizing the performance of metals rather than supported substrates by using this strategy. In this work, we mainly investigate the influence of an EMSI effect on the performance of the supported substrate (Ti3C2Tx MXene). Detailed scanning electrochemical microscopy and numerical simulations results reveal that the charge distribution on the Ti3C2Tx basal plane (approximate 100 nm-radius) surrounding Au nanoparticles (20 nm-radius) was significantly enhanced as a result of —O being the majority surface functional group on Ti3C2Tx that was attached to Au nanoparticle, and the related hydrogen evolution reaction (HER) activity was much better than that of the unaffected Ti3C2Tx basal plane, which even can be comparable to that of Au. This finding will be helpful for designing new strategies to enhance the overall catalytic performance of various MXene-based composites. [ABSTRACT FROM AUTHOR]

Scanning electrochemical cell microscopy (SECCM) is increasingly applied to determine the intrinsic catalytic activity of single electrocatalyst particle. This is especially feasible if the catalyst nanoparticles are large enough that they can be found and counted in post-SECCM scanning electron microscopy images. Evidently, this becomes impossible for very small nanoparticles and hence, a catalytic current measured in one landing zone of the SECCM droplet cannot be correlated to the exact number of catalyst particles. We show, that by introducing a ruler method employing a carbon nanoelectrode decorated with a countable number of the same catalyst particles from which the catalytic activity can be determined, the activity determined using SECCM from many spots can be converted in the intrinsic catalytic activity of a certain number of catalyst nanoparticles. [ABSTRACT FROM AUTHOR]

At the most fundamental level, the behavior of tissue is governed by the activity of its single cells. A detailed examination of single-cell biology is necessary in order to gain a deeper understanding of disease progression. While single-cell genomics and transcriptomics are mature due to robust amplification strategies, the metabolome is difficult to quantify. Nanoelectrochemical techniques stand poised to quantify single-cell metabolism as a result of the fabrication of nanoelectrodes, which allow one to make intracellular electrochemical measurements. This article is concerned with intracellular nanoelectrochemistry, focusing on the sensitive and selective quantification of various metabolites within a single, living cell. We will review the strong literature behind this field, discuss the potential deleterious effects of passing charge inside cells, and provide future outlooks for this promising avenue of inquiry. We also present a mathematical relationship based on Faraday's Law and bulk electrolysis theory to examine the consumption of analyte within a cell due to passing charge at the nanotip. Graphical abstract [ABSTRACT FROM AUTHOR]

Label-free biosensing has been the dream of scientists and biotechnologists as reported by Vollmer and Arnold (Nat Methods 5:591–596, 2008). The ability of examining living cells is crucial to cell biology as noted by Fang (Int J Electrochem 2011:460850, 2011). Chemical measurement with electrodes is label-free and has demonstrated capability of studying living cells. In recent years, nanoelectrodes of different functionality have been developed. These nanometer-sized electrodes, coupled with scanning electrochemical microscopy (SECM), have further enabled nanometer spatial resolution study in aqueous environments. Developments in the field of nanoelectrochemistry have allowed measurement of signaling species at single cells, contributing to better understanding of cell biology. Leading studies using nanoelectrochemistry of a variety of cellular signaling molecules, including redox-active neurotransmitter (e.g., dopamine), non-redox-active neurotransmitter (e.g., acetylcholine), reactive oxygen species (ROS), and reactive nitrogen species (RNS), are reviewed here. [ABSTRACT FROM AUTHOR]

Nanopore techniques are experiencing a gallop since it walked out the notebook and show its charm on the science arena. The nanoscale pore offers a single-molecule resolution with a label-free and high-selective manner for the research of molecular structures, molecular dynamics, single-molecule reactions and for a variety of applications in biophysics and bionanotechnology. In this review, we introduce the construction of three types of nanopore platforms along with the latest progress in DNA sensing, structure and dynamics analysis of peptides/proteins, and the detection of redox reactions with new sensing mechanisms. Then, we depict nanopore data processing methods which provide an insight of data mining under the background of big data. We could fully expect the great impact of nanopore techniques on not only for DNA sequencing and sensing applications, but also in protein sequencing and clinical diagnostics. [ABSTRACT FROM AUTHOR]