Mechanical Strain Induces and Increases Vesicular Release Monitored by Microfabricated Stretchable Electrodes

Exocytosis involving the fusion of intracellular vesicles with cell membrane, is thought to be modulated by the mechanical cues in the microenvironment. Single-cell electrochemistry can offer unique information about the quantification and kinetics of exocytotic events; however, the effects of mechanical force on vesicular release have been poorly explored. Herein, we developed a stretchable microelectrode with excellent electrochemical stability under mechanical deformation by microfabrication of functionalized poly(3,4-ethylenedioxythiophene) conductive ink, which achieved real-time quantitation of strain-induced vesicular exocytosis from a single cell for the first time. We found that mechanical strain could cause calcium influx via the activation of Piezo1 channels in chromaffin cell, initiating the vesicular exocytosis process. Interestingly, mechanical strain increases the amount of catecholamines released by accelerating the opening and prolonging the closing of fusion pore during exocytosis. This work is expected to provide revealing insights into the regulatory effects of mechanical stimuli on vesicular exocytosis.

A Flexible and Transparent PtNP/SWCNT/PET Electrochemical Sensor for Nonenzymatic Detection of Hydrogen Peroxide Released from Living Cells with Real-Time Monitoring Capability

We developed a transparent and flexible electrochemical sensor using a platform based on a network of single-walled carbon nanotubes (SWCNTs) for the non-enzymatic detection of hydrogen peroxide (H₂O₂) released from living cells. We decorated the SWCNT network on a poly(ethylene terephthalate) (PET) substrate with platinum nanoparticles (PtNPs) using a potentiodynamic method. The PtNP/SWCNT/PET sensor synergized the advantages of a flexible PET substrate, a conducting SWCNT network, and a catalytic PtNP and demonstrated good biocompatibility and flexibility, enabling cell adhesion. The PtNP/SWCNT/PET-based sensor demonstrated enhanced electrocatalytic activity towards H₂O₂, as well as excellent selectivity, stability, and reproducibility. The sensor exhibited a wide dynamic range of 500 nM to 1 M, with a low detection limit of 228 nM. Furthermore, the PtNP/SWCNT/PET sensor remained operationally stable, even after bending at various angles (15°, 30°, 60°, and 90°), with no noticeable loss of current signal. These outstanding characteristics enabled the PtNP/SWCNT/PET sensor to be practically applied for the direct culture of HeLa cells and the real-time monitoring of H₂O₂ release by the HeLa cells under drug stimulation.

Raman Fiber Photometry for Understanding Mitochondrial Superoxide Burst and Extracellular Calcium Ion Influx upon Acute Hypoxia in the Brain of Freely Moving Animals

Developing a novel tool capable of real-time monitoring and simultaneous quantitation of multiple molecules in mitochondria across the whole brain of freely moving animals is the key bottleneck for understanding the physiological and pathological roles that mitochondria play in the brain events. Here we built a Raman fiber photometry, and created a highly selective non-metallic Raman probe based on the triple-recognition strategies of chemical reaction, charge transfer, and characteristic fingerprint peaks, for tracking and simultaneous quantitation of mitochondrial O₂ ^.- , Ca²⁺ and pH at the same location in six brain regions of free-moving animal upon hypoxia. It was found that mitochondrial O₂ ^.- , Ca²⁺ and pH changed from superficial to deep brain regions upon hypoxia. It was discovered that hypoxia-induced mitochondrial O₂ ^.- burst was regulated by ASIC1a, leading to mitochondrial Ca²⁺ overload and acidification. Furthermore, we found the overload of mitochondrial Ca²⁺ was mostly attributed to the influx of extracellular Ca²⁺ .

Au nanoflower film-based stretchable biosensors for in situ monitoring of superoxide anion release in cell mechanotransduction

Cell mechanotransduction plays an important role in vascular regulation and disease development.

Deep Learning for Voltammetric Sensing in a Living Animal Brain

Numerous neurochemicals have been implicated in the modulation of brain function, making them appealing analytes for sensors and diagnostics. However, it is a grand challenge to selectively measure multiple neurochemicals simultaneously in vivo because of their great variations in concentrations, dynamic nature, and composition. Herein, we present a deep learning-based voltammetric sensing platform for the highly selective and simultaneous analysis of three neurochemicals in a living animal brain. The system features a carbon fiber electrode capable of capturing the mixed dynamics of a neurotransmitter, neuromodulator, and ions. Then a powerful deep neural network is employed to resolve individual chemical and spatial-temporal information. With this, a single electrochemical measurement reveals an interplaying concentration changes of dopamine, ascorbate, and ions in living rat brain, which is unobtainable with existing analytical methodologies. Our strategy provides a powerful means to expedite research in neuroscience and empower sensing-aided diagnostic applications.

Soft Wearable Healthcare Materials and Devices

In spite of advances in electronics and internet technologies, current healthcare remains hospital-centred. Disruptive technologies are required to translate state-of-art wearable devices into next-generation patient-centered diagnosis and therapy. In this review, recent advances in the emerging field of soft wearable materials and devices are summarized. A prerequisite for such future healthcare devices is the need of novel materials to be mechanically compliant, electrically conductive, and biologically compatible. It is begun with an overview of the two viable design strategies reported in the literatures, which is followed by description of state-of-the-art wearable healthcare devices for monitoring physical, electrophysiological, chemical, and biological signals. Self-powered wearable bioenergy devices are also covered and sensing systems, as well as feedback-controlled wearable closed-loop biodiagnostic and therapy systems. Finally, it is concluded with an overall summary and future perspective.

Long-Term Tracking and Dynamically Quantifying of Reversible Changes of Extracellular Ca2+ in Multiple Brain Regions of Freely Moving Animals

Understanding physiological and pathological processes in the brain requires tracking the reversible changes in chemical signals with long-term stability. We developed a new anti-biofouling microfiber array to real-time quantify extracellular Ca²⁺ concentrations together with neuron activity across many regions in the mammalian brain for 60 days, in which the signal degradation was < ca. 8 %. The microarray with high tempo-spatial resolution (ca. 10 μm, ca. 1.3 s) was implanted into 7 brain regions of free-moving mice to monitor reversible changes of extracellular Ca²⁺ upon ischemia-reperfusion processes. The changing sequence and rate of Ca²⁺ in 7 brain regions were different during the stroke. ROS scavenger could protect Ca²⁺ influx and neuronal activity after stroke, suggesting the significant influence of ROS on Ca²⁺ overload and neuron death. We demonstrated this microarray is a versatile tool for investigating brain dynamic during pathological processes and drug treatment.