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The glutathione (GSH) system is one of the most powerful intracellular antioxidant systems for the elimination of reactive oxygen species (ROS) and maintaining cellular redox homeostasis. However, the rapid kinetics information (at the millisecond to the second level) during the dynamic antioxidation process of the GSH system remains unclear. As such, we specifically developed a novel dual-wire nanosensor (DWNS) that can selectively and synchronously measure the levels of GSH and ROS with high temporal resolution, and applied it to monitor the transient ROS generation as well as the rapid antioxidation process of the GSH system in individual cancer cells. These measurements revealed that the glutathione peroxidase (GPx) in the GSH system is rapidly initiated against ROS burst in a sub-second time scale, but the elimination process is short-lived, ending after a few seconds, while some ROS are still present in the cells. This study is expected to open new perspectives for understanding the GSH antioxidant system and studying some redox imbalance-related physiological., (© 2023 Wiley-VCH GmbH.)

Interfacing biological tissues with electronic sensors offers the exciting opportunity to accurately investigate multiple biological processes. Accurate signal collection and application are the foundation of these measurements, but a long-term issue is the signal distortion resulting from the interface gap. The height of the gap is the key characteristic needed to evaluate or model the distortion, but it is difficult to measure. By integrating a pair of nanopores at the electronic sensor plane and measuring the ion conductance between them, we developed a versatile and straightforward strategy to realize the direct cooperative evaluation of the gap height during exocytotic release from adrenal gland tissues. The signaling distortion of this gap has been theoretically evaluated and shows almost no influence on the amperometric recording of exocytosis in a classic "semi-artificial synapse" configuration. This strategy should benefit research concerning various bio/chemical/machine interfaces., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The existence of a homeostatic mechanism regulating reactive oxygen/nitrogen species (ROS/RNS) amounts inside phagolysosomes has been invoked to account for the efficiency of this process but could not be unambiguously documented. Now, intracellular electrochemical analysis with platinized nanowire electrodes (Pt-NWEs) allowed monitoring ROS/RNS effluxes with sub-millisecond resolution from individual phagolysosomes impacting onto the electrode inserted inside a living macrophage. This shows for the first time that the consumption of ROS/RNS by their oxidation at the nanoelectrode surface stimulates the production of significant ROS/RNS amounts inside phagolysosomes. These results establish the existence of the long-postulated ROS/RNS homeostasis and allows its kinetics and efficiency to be quantified. ROS/RNS concentrations may then be maintained at sufficiently high levels for sustaining proper pathogen digestion rates without endangering the macrophage internal structures., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nanoelectrodes allow precise and quantitative measurements of important biological processes at the single living-cell level in real time. Cylindrical nanowire electrodes (NWEs) required for intracellular measurements create a great challenge for achieving excellent electrochemical and mechanical performances. Herein, we present a facile and robust solution to this problem based on a unique SiC-core-shell design to produce cylindrical NWEs with superior mechanical toughness provided by the SiC nano-core and an excellent electrochemical performance provided by the ultrathin carbon shell that can be used as such or platinized. The use of such NWEs for biological applications is illustrated by the first quantitative measurements of ROS/RNS in individual phagolysosomes of living macrophages. As the shell material can be varied to meet any specific detection purpose, this work opens up new opportunities to monitor quantitatively biological functions occurring inside cells and their organelles., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electrode fouling and passivation is a substantial and inevitable limitation in electrochemical biosensing, and it is a great challenge to efficiently remove the contaminant without changing the surface structure and electrochemical performance. Herein, we propose a versatile and efficient strategy based on photocatalytic cleaning to construct renewable electrochemical sensors for cell analysis. This kind of sensor was fabricated by controllable assembly of reduced graphene oxide (RGO) and TiO2 to form a sandwiching RGO@TiO2 structure, followed by deposition of Au nanoparticles (NPs) onto the RGO shell. The Au NPs-RGO composite shell provides high electrochemical performance. Meanwhile, the encapsulated TiO2 ensures an excellent photocatalytic cleaning property. Application of this renewable microsensor for detection of nitric oxide (NO) release from cells demonstrates the great potential of this strategy in electrode regeneration and biosensing., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Chemical synaptic transmission is central to the brain functions. In this regard, real-time monitoring of chemical synaptic transmission during neuronal communication remains a great challenge. In this work, in vivo-like oriented neural networks between superior cervical ganglion (SCG) neurons and their effector smooth muscle cells (SMC) were assembled in a microfluidic device. This allowed amperometric detection of individual neurotransmitter release events inside functional SCG-SMC synapse with carbon fiber nanoelectrodes as well as recording of postsynaptic potential using glass nanopipette electrodes. The high vesicular release activities essentially involved complex events arising from flickering fusion pores as quantitatively established based on simulations. This work allowed for the first time monitoring in situ chemical synaptic transmission under conditions close to those found in vivo, which may yield important and new insights into the nature of neuronal communications., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Chemical neurotransmission occurs at chemical synapses and endocrine glands, but up to now there was no means for direct monitoring of neurotransmitter exocytosis fluxes and their precise kinetics from inside an individual synapse. The fabrication of a novel finite conical nanoelectrode is reported perfectly suited in size and electrochemical properties for probing amperometrically inside what appears to be single synapses and monitoring individual vesicular exocytotic events in real time. This allowed obtaining direct and important physiological evidences which may yield important and new insights into the nature of synaptic communications., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)