H2O2 and polarity are quite important in many physiological and pathological processes, and their relationship is complicated and obscure for researchers. Thus, it is vital and challenging to achieve simultaneous detection of H2O2 and polarity in vivo. Herein, the first naphthalimide-triphenylamine-based dual-site fluorescent probe NATPA is developed for simultaneously imaging intracellular H2O2 and polarity fluctuations. It exhibits excellent sensitivity (LOD = 44 nM), selectivity, and fast response (15 min) to H2O2 and a superior capacity for detecting polarity upon the intramolecular charge transfer (ICT) effect. Besides, the probe displays low cytotoxicity and lipid droplet targeting and is further applied in imaging H2O2 and polarity fluctuations in HepG2 and L-02 cells, so that NATPA is qualified to distinguish cancer cells from normal cells. This research contributes a new design principle for the construction of dual-site fluorescent probes for simultaneously detecting active molecules and polarity.

Lipid Droplet-Specific Dual-Response Fluorescent Probe for the Detection of Polarity and H2O2 and Its Application in Living Cells.

Near-infrared fluorescence probe with a large Stokes shift for selectively imaging of hydrogen peroxide in living cells and in vivo

Hydrogen peroxide (H2O2), one of the most stable and abundant reactive oxygen species (ROS), acting as a modulator of dopaminergic signaling, has been intimately implicated in Parkinson's disease, creating a critical need for the selective quantification of H2O2 in the living brain. Current natural or nanomimic enzyme-based electrochemical methods employed for the determination of H2O2 suffer from inadequate selectivity and stability, due to which the in vivo measurement of H2O2 in the living brain remains a challenge. Herein, a series of 5-(1,2-dithiolan-3-yl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)pentanamide (DBP) derivatives were designed by tuning the substitute groups and sites of a boric acid ester, which served as probes to specifically react with H2O2. Consequently, the reaction products, 5-(1,2-dithiolan-3-yl)-N-(4-hydroxyphen-yl)pentanamide (DHP) derivatives, converted the electrochemical signal from inactive into active. After systematically evaluating their performances, 5-(1,2-dithiolan-3-yl)-N-(3-chloro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)pentanamide (o-Cl-DBP) was finally identified as the optimized probe for H2O2 detection as it revealed the fastest reaction time, the largest current density, and the most negative potential. In addition, electrochemically oxidized graphene oxide (EOGO) was utilized to produce a stable inner reference. The designed electrochemical microsensor provided a ratiometric strategy for real-time tracking of H2O2 in a linear range of 0.5-600 μM with high selectivity and accuracy. Eventually, the efficient electrochemical microsensor was successfully applied to the measurement of H2O2 in Parkinson's disease (PD) mouse brain. The average levels of H2O2 in the cortex, striatum, and hippocampus in the normal mouse and PD mouse were systematically compared for the first time.

Efficient Electrochemical Microsensor for In Vivo Monitoring of H2O2 in PD Mouse Brain: Rational Design and Synthesis of Recognition Molecules.

Fast Response Fluorescent Probe with a Large Stokes Shift for Thiophenol Detection in Water Samples and Cell Imaging

In this study, we report the construction of a turn-on fluorescent probe, TMN-H2O2 with near-infrared emission for H2O2 detection in living systems. A series of experiments demonstrated that TMN-H2O2 exhibits a high selectivity for H2O2. After reaction with H2O2, TMN-H2O2 exhibited a 14.3-fold increase in fluorescence intensity at 660 nm and a 180 nm large Stokes shift. Moreover, TMN-H2O2 exhibited excellent sensitivity (limit of detection: 76 nM) and a fast response time (~40 min). The successful in vitro and in vivo application of TMN-H2O2 therefore suggested that this probe is a reliable chemical tool for monitoring both endogenous and exogenous H2O2.

A NIR fluorescent probe for the in vitro and in vivo selective detection of hydrogen peroxide

All-dielectric metamaterials (ADMs) have recently attracted much attention due to their ability to achieve wavefront control with high power capability. In this article, an investigation on quasi-optical mode converter (QOC) based on ADM for high-order vacuum electronics devices (VEDs) is presented. Specifically, four ADM QOCs are designed to convert the cylindrical waveguide TE01, TE21, TE31, and TM01 modes into linear polarized Gaussian beams at 35 GHz. Electromagnetic simulations show that the Gaussian mode contents of the output waves from four mode converters are all over 94% with high polarization contents. Furthermore, a Ka-band ADM mode converter with the input mode of circular waveguide TE01 mode is fabricated and measured. Experimental results show that the output fields with scalar Gaussian content over 90% can be obtained at 30–38.85 GHz, corresponding to a relative bandwidth of 25.3% around 35 GHz. The maximum scalar Gaussian mode content of 99.18% is observed at 34.56 GHz in the experiment. The investigation opens new avenues toward high-order mode conversion technology based on ADM.

Quasi-Optical Mode Converter Based on All-Dielectric Metamaterial for High-Order Mode Vacuum Electronics Devices

Magnetic field system is one of the most crucial components for gyrotron operation. A compact gyrotron with a custom-designed magnet would be a promising continuous radiation source for millimeter-wave power applications. In this article, a design and preliminary experiment of a room-temperature Bitter magnet for developing compact gyrotron are presented. To lengthen the magnetic field homogeneity region without dramatically improving power consumption, a special design that every Bitter segment with different outer radii is adopted. Both in simulation and experimental measurement, the length of the homogeneity region is 120 mm, and homogeneity $\Delta {B}/{B}$ is ±0.9% is obtained. A 5 kV magnetron injection gun (MIG) was designed based on the experimental measurement of this Bitter magnet, in which a velocity ratio of 1.3 and transverse velocity spread of 12% were obtained at current 0.5 A in simulation.

Shi Hu

Papers

A NIR fluorescent probe for the in vitro and in vivo selective detection of hydrogen peroxide

Quasi-Optical Mode Converter Based on All-Dielectric Metamaterial for High-Order Mode Vacuum Electronics Devices

Design and Preliminary Experiment of Room-Temperature Bitter Magnet for Compact Gyrotron