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Serotonin, a monoamine neurotransmitter, is important in both the central nervous system (CNS) and the peripheral nervous system. Malfunction of serotonin signaling leads to various disorders. We studied serotonin signaling from serotonergic neurons inside the ventral nerve cord of Drosophila melanogaster. Serotonergic neurons and stimulated release were visualized and achieved with mCherry and channelrhodopsin‐2 (an optogenetically transfected ion channel), respectively, and two electrochemical techniques quantified serotonin release and vesicular content. Mean vesicular serotonin content released during exocytosis from these neurons was 84 %, considerably higher than reported in previous studies regarding octopamine (4.5 %) and glutamate release (31 %). Serotonin content within all vesicles is uniformly changed when serotonin concentration is inhibited or enhanced. However, serotonin release exhibits two Gaussian distributions: higher frequency of small release events, and similar or slightly higher frequency of large events, resulting in differential release fractions ranging from partial (13–18 %) to full (100 %) release after treatment with agents to either enhance or diminish release. This is the first example of consistent full exocytotic release events we have observed in any system. We suggest one pool of vesicles can release significantly diverse fractions of transmitter load during exocytosis, a potentially novel pathway to regulate exocytosis and neuronal signaling. [ABSTRACT FROM AUTHOR]

The in‐depth study of single cells requires the dynamically molecular information in one particular nanometer‐sized organelle in a living cell, which is difficult to achieve using current methods. Due to high efficiency of click chemistry, a new nanoelectrode‐based pipette architecture with dibenzocyclooctyne at the tip is designed to realize fast conjugation with azide group‐containing triphenylphosphine, which targets mitochondrial membranes. The covalent binding of one mitochondrion at the tip of the nanopipette allows a small region of the membrane to be isolated on the Pt surface inside the nanopipette. Therefore, the release of reactive oxygen species (ROS) from the mitochondrion is monitored, which is not interfered by the species present in the cytosol. The dynamic tracking of ROS release from one mitochondrion reveals the distinctive "ROS‐induced ROS release" within the mitochondria. Further study of RSL3‐induced ferroptosis using nanopipettes provides direct evidence for supporting the noninvolvement of glutathione peroxidase 4 in the mitochondria during RSL3‐induced ROS generation, which has not previously been observed at the single‐mitochondrion level. Eventually, this established strategy should overcome the existing challenge of the dynamic measurement of one special organelle in the complicated intracellular environment, which opens a new direction for electroanalysis in subcellular analysis. [ABSTRACT FROM AUTHOR]

Nanoelectrochemistry allows for the investigation of the interaction of per‐ and polyfluoroalkyl substances (PFASs) with silver nanoparticles (AgNPs) and the elucidation of the binding behaviour of PFASs to nanoscale surfaces with high sensitivity. Mechanistic studies supported by single particle collision electrochemistry (SPCE), spectroscopic and density functional theory (DFT) calculations indicate the capability of polyfluorooctane sulfonic acid (PFOS), a representative PFAS, to selectively bind and induce aggregation of AgNPs. Single‐particle measurements provide identification of the "discrete" AgNPs agglomeration (e.g. 2–3 NPs) formed through the inter‐particles F−F interactions and the selective replacement of the citrate stabilizer by the sulfonate of the PFOS. Such interactions are characteristic only for long chain PFAS (‐SO3−) providing a means to selectively identify these substances down to ppt levels. Measuring and understanding the interactions of PFAS at nanoscale surfaces are crucial for designing ultrasensitive methods for detection and for modelling and predicting their interaction in the environment. [ABSTRACT FROM AUTHOR]

The transport of molecules and ions through biological nanopores is governed by interaction networks among restricted ions, transported molecules, and residue moieties at pore inner walls. However, identification of such weak ion fluctuations from only few tens of ions inside nanopore is hard to achieve owing to electrochemical measurement limitations. Here, we developed an advanced frequency method to achieve qualitative and spectral analysis of ion interaction networks inside a nanopore. The peak frequency fm reveals the dissociation rate between nanopore and ions; the peak amplitude am depicts the amount of combined ions with the nanopore after interaction equilibrium. A mathematical model for single‐molecule frequency fingerprint achieved the prediction of interaction characteristics of mutant nanopores. This single‐molecule frequency fingerprint is important for classification, characterization, and prediction of synergetic interaction networks inside nanoconfinement. [ABSTRACT FROM AUTHOR]

Detection, Nanoelectrochemistry, Nanoparticles, PFAS, Surface Interactions GLO:OL3/17oct22:ange202212561-gra-0003.jpg PHOTO (COLOR): . gl B Donor - Akzeptor-Systeme b In ihrer Zuschrift (e202209225) demonstrieren Christoph Weder, Yoshimitsu Sagara et al. den ersten Cyclophan-Mechanophor, der die Emission von Ladungstransferkomplexen nutzt. Keywords: Detection; Nanoelectrochemistry; Nanoparticles; PFAS; Surface Interactions EN Detection Nanoelectrochemistry Nanoparticles PFAS Surface Interactions 1 1 1 10/13/22 20221017 NES 221017 B Nanoelektrochemie b unter Verwendung von Einzelteilchenkollisionen an Mikroelektroden, unterstützt durch spektroskopische und theoretische Studien, bietet Einblicke in die molekularen Wechselwirkungen von Perfluoralkylsubstanzen (PFAS) auf Einzelpartikelebene. [Extracted from the article]

Ion interaction networks, nanoelectrochemistry, nanopore, single-molecule analysis Keywords: ion interaction networks; nanoelectrochemistry; nanopore; single-molecule analysis EN ion interaction networks nanoelectrochemistry nanopore single-molecule analysis 24537 24537 1 11/02/21 20211108 NES 211108 B Wie bei einem Musikkasten b werden beim Nanoporen-Einzelmolekül-Frequenzfingerprinting ein rotierender Metallzylinder (ein Analyt) und perfekt platzierte Stifte (die chemischen Gruppen eines Analyten) genutzt, welche die Zacken oder Zinken (die charakteristischen Reste in der Nanoporeninnenwand) des Kamms anschlagen. Titelbild: Single-Molecule Frequency Fingerprint for Ion Interaction Networks in a Confined Nanopore (Angew. [Extracted from the article]