Design, synthesis and application of dual-channel fluorescent probes for ratiometric detection of HClO and H2S based on phenothiazine coumarins.

The ubiquity of diverse material entities in environmental matrices renders the deployment of unifunctional fluorescent indicators inadequate. Consequently, this study introduces a ratiometric dual-emission fluorescent sensor (Probe CP), synthesized by conjugating phenothiazine coumarin to hydroxycoumarin through a piperazine linker for concurrent detection of HClO and H2S. Upon interaction with HClO, the phenothiazine unit's sulfur atom undergoes oxidation to sulfoxide, facilitating a shift from red to green fluorescence in a ratiometric manner. Concurrently, at the opposite terminus of Probe CP, 2,4-dinitroanisole serves as the reactive moiety for H2S recognition; it restores the blue emission characteristic of 7-hydroxycoumarin while maintaining the red fluorescence emanating from phenothiazine coumarin as an internal standard for ratio-based assessment. Exhibiting elevated specificity and sensitivity coupled with minimal detection thresholds (0.0506 µM for HClO and 1.7292 µM for H2S) alongside rapid equilibration periods (3 min for HClO and half an hour for H2S), this sensor was efficaciously employed in cellular environments and within zebrafish models as well as imaging applications pertaining to alcohol-induced hepatic injury in murine subjects.

Bioimaging of a chromenoquinoline-based ratiometric fluorescent probe for detecting ClO.

Hypochlorous acid (HClO) is a reactive oxygen species and a relatively strong antibacterial substance in the immune defense system. The normal concentration of HClO in the human body is approximately 200 µM, and its high concentration can cause tissue damage and some diseases. Herein, a chromenoquinoline-based ratiometric fluorescent probe was developed to detect and quantify HClO. The developed Probe 1 exhibited the advantages of large Stokes shift (137 nm), high synthetic yield (84.7 %), simple synthesis method, short response time (<4 min), low detection limit (5.1 nM), and low toxicity. The probe was successfully validated in live cells and zebrafish.

Mechano-Electrochemically Promoting Lithium Atom Diffusion and Relieving Accumulative Stress for Deep-Cycling Lithium Metal Anodes.

Lithium metal batteries (LMBs) can double the energy density of lithium-ion batteries. However, the notorious lithium dendrite growth and large volume change are not well addressed, especially under deep cycling. Here, an in-situ mechanical-electrochemical coupling system is built, and it is found that tensile stress can induce smooth lithium deposition. Density functional theory (DFT) calculation and finite element method (FEM) simulation confirm that the lithium atom diffusion energy barrier can be reduced when the lithium foils are under tensile strain. Then tensile stress is incorporated into lithium metal anodes by designing an adhesive copolymer layer attached to lithium in which the copolymer thinning can yield tensile stress to the lithium foil. Elastic lithium metal anode (ELMA) is further prepared via introducing a 3D elastic conductive polyurethane (CPU) host for the copolymer-lithium bilayer to release accumulated internal stresses and resist volume variation. The ELMA can withstand hundreds of compression-release cycles under 10% strain. LMBs paired with ELMA and LiNi0.8 Co0.1 Mn0.1 O2 (NCM811) cathode can operate beyond 250 cycles with 80% capacity retention under practical condition of 4 mAh cm-2 cathode capacity, 2.86 g Ah-1 electrolyte-to-capacity ratio (E/C) and 1.8 negative-to-cathode capacity ratio (N/P), five times of the lifetime using lithium foils.

Rapid Self-Healing Gel Electrolyte Based on Deep Eutectic Solvents for Solid-State Lithium Batteries.

A deep eutectic solvent (DES) is a promising electrolyte choice for lithium metal batteries. However, the DES liquid electrolyte causes safety concerns and side reactions with the lithium anode. Therefore, it is necessary to solidify the DES-based electrolyte and enhance its electrochemical stability. Herein, we present a novel DES-based rapid self-healing gel electrolyte, which is able to self-smooth its surface cracks in only 30 min. The electrolyte exhibits noncombustibility (SET = 4 s g-1), high ionic conductivity (1.1 × 10-3 S cm-1 at 25 °C), and a wide electrochemical voltage window (4.5 V vs Li/Li+). As a result, the solid-state lithium batteries coupling the gel electrolyte with the Li anode and LiFePO4 cathode deliver a high specific capacity of 135.4 mA h g-1 with durable cyclic stability (>1200 h). This work provides valuable insights for design of fire-resistant and high-energy solid-state lithium batteries.

Self-Healable, Strong, and Tough Polyurethane Elastomer Enabled by Carbamate-Containing Chain Extenders Derived from Ethyl Carbonate.

Commercial diol chain extenders generally could only form two urethane bonds, while abundant hydrogen bonds were required to construct self-healing thermoplastic polyurethane elastomers (TPU). Herein, two diol chain extenders bis(2-hydroxyethyl) (1,3-pheny-lene-bis-(methylene)) dicarbamate (BDM) and bis(2-hydroxyethyl) (methylenebis(cyclohexane-4,1-diy-l)) dicarbamate (BDH), containing two carbamate groups were successfully synthesized through the ring-opening reaction of ethylene carbonate (EC) with 1,3-benzenedimetha-namine (MX-DA) and 4, 4'-diaminodicyclohexylmethane (HMDA). The two chain extenders were applied to successfully achieve both high strength and high self-healing ability. The BDM-1.7 and BDH-1.7 elastomers had high comprehensive self-healing efficiency (100%, 95%) after heated treatment at 60 °C, and exhibited exceptional comprehensive mechanical performances in tensile strength (20.6 ± 1.3 MPa, 37.1 ± 1.7 MPa), toughness (83.5 ± 2.0 MJ/m3, 118.8 ± 5.1 MJ/m3), puncture resistance (196.0 mJ, 626.0 mJ), and adhesion (4.6 MPa, 4.8 MPa). The peculiar mechanical and self-healing properties of TPUs originated from the coexisting short and long hard segments, strain-induced crystallization (SIC). The two elastomers with excellent properties could be applied to engineering-grade fields such as commercial sealants, adhesives, and so on.

Application of Fluorescent Probes in Reactive Oxygen Species Disease Model.

Reactive oxygen species (ROS) play an important role in living activities as signaling molecules that regulate the living activities of organisms. There are many types of ROS, mainly including hydrogen peroxide (H2O2), hypochlorous acid (HOCl), hydroxyl radical (•OH), peroxyl radical (ROO•), singlet oxygen (1O2), peroxynitrite (ONOO-) and superoxide anion radical (O2-•) etc. Existing studies have shown that changes in ROS levels are closely associated with the development of many diseases, such as inflammation, cancer, cardiovascular disease, and neurodegenerative damage. Small molecule fluorescent probes have been widely used in biology, pathology and medical diagnosis due to their advantages of noninvasive, high sensitivity and in vivo real-time detection. It is extremely important to better apply small-molecule fluorescent probes to detect ROS levels in organisms to achieve early diagnosis of diseases and assessment of therapeutic conditions. This work focuses on summarizing the representative applications of some fluorescent probes in ROS disease models in recent years. This article focuses on summarizing the construction methods of various ROS-related disease models, and classifying and analyzing the basic ideas and methods of fluorescent probes applied to disease models according to the characteristics of various diseases.

Enriching Oxygen Vacancy Defects via Ag-O-Mn Bonds for Enhanced Diffusion Kinetics of δ-MnO2 in Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) have received great attention due to their environmental friendliness and high safety. However, cathode materials with slow diffusion dynamics and dissolution in aqueous electrolytes hindered their further application. To address these issues, in this work, a MnO2-2 cathode doped with 1.12 wt % Ag was prepared, and after 1000 cycles of charge/discharge at 1 A·g-1, the capacity remained at 114 mA·h·g-1 (only 57.7 mA·h·g-1 for pristine MnO2). Cyclic voltammetry (CV), the galvanostatic intermittent titration technique (GITT), the electrochemical quartz crystal microbalance (EQCM) method, and density functional theory (DFT) calculation on pristine δ-MnO2 and MnO2-2 also proved the superior performance of MnO2-2. More investigation disclosed that its superior performance is attributed to the improved diffusion kinetics of the cathode brought by the enriched oxygen vacancy defects due to the formation of Ag-O-Mn bonds. Meanwhile, the kinetic mechanism of the Zn/MnO2-2 cell can be described as a reversible process of the dissolution/precipitation of the ZHS phase and consequent insertion/extraction of Zn2+ and H3O+. Herein, the primary issues of ZIB cathode materials have been addressed and solved to a certain extent. More importantly, such a modification in the design of the advanced manganese-based aqueous ZIB cathode materials can provide further insight and facilitate the development and application of this large-scale energy storage system in the near future.

An Environmentally Friendly Supramolecular Glue Developed from Natural 3,4-Dihydroxybenzaldehyde.

Liquid adhesive suffers from the emission of volatile organic compounds (VOCs) that have detrimental effects on human beings. Herein, an environmentally friendly glue containing a novel supramolecule dissolved in non-toxic ethanol is developed. Poly (ether amine) (PEA) and 3,4-dihydroxybenzaldehyde (dhba) is utilized to synthesize catechol-terminated PEA, and subsequent complexation by Fe3+ results in the supramolecular component (PEA-dhba-Fe3+). The Fourier transform infrared (FTIR) spectrum together with the UV-vis spectrum reveal the existence of quinone converted from catechol. Raman spectra prove the existence of a successful complex of catechol-terminated PEA with Fe3+. The tri-complex is found to be the predominant mode and can successfully form into clusters, serving as a physical cross-linking network. The PEA-dhba-Fe3+ exhibits strong adherence to metal substrates compared to polymeric substrates, with its shear strength reaching as high as 1.36 ± 0.14 MPa when the pH of the glue is adjusted to 8. The obvious improvement of adhesion originates from the formation of interfacial coordination bonds between quinone/catechol and metal atoms, as well as their cations, as revealed by X-ray photoelectron spectroscopy (XPS) and theoretical calculations. With consideration of its merits, including strong adhesion and the minor emission of VOCs compared to commercial epoxy and acrylic adhesives, this environmentally friendly supramolecular glue has a range of cutting-edge applications as an adhesive for metal substrates.

Dual-Ratiometric Fluorescent Probe for H2O2 and HClO in Living Cells and Zebrafish and Application in Alcoholic Liver Injury Monitoring.

Reactive oxygen species (ROS) are an important component for maintaining normal physiological activities in organisms, and abnormal changes in their level are often accompanied by many diseases. As the two most representative components of ROS, HClO and H2O2 play vital roles in many physiological and pathological processes and are interdependent and mutually transformable. Although there is a lot of work that has specifically detected HClO or H2O2, there are few reports on the simultaneous differential detection of HClO and H2O2. Here, we report a ratio-based fluorescent probe capable of simultaneously distinguishing HClO and H2O2 based on making the best use of the untapped potential of coumarin derivatives. This probe was triumphantly put into use in the discriminative identification of HClO and H2O2 in aqueous media with high sensitivity and selectivity, and the probe was appropriate in a wide pH range. Furthermore, the imaging experiment for HClO and H2O2 in cells and zebrafish was eventually proven to be feasible. Importantly, this probe was qualified for monitoring the variation of HClO and H2O2 levels in organisms with alcoholic liver injury.

Balance of N-Doping Engineering and Carbon Chemistry to Expose Edge Graphitic N Sites for Enhanced Oxygen Reduction Electrocatalysis.

Nitrogen-doped nanocarbon materials (NCMs) have been developed as promising metal-free oxygen reduction reaction (ORR) electrocatalysts. However, insufficient attention on the balance of N-doping engineering and carbon chemistry significantly suppressed the revelation of the real active configurations as well as the ORR mechanism for NCMs. Herein, 1,4-phenylenediurea (BDU) with multifunctional blocks was designed for the synthesis of NCMs, realizing synchronous manipulation of N-doping engineering and carbon chemistry. The good balance between N-doping engineering (especially graphitic edge N configurations) and carbon chemistry (including the specific surface area, porosity distribution, and graphitization degree) at a pyrolysis temperature of 1000 °C resulted in the best ORR performance for obtaining N-doped carbon nanorod (NCR) materials. A general descriptor χ was then proposed for evaluating the balance states between N-doping engineering and carbon chemistry. The prediction of the ORR performance of NCMs from their physical properties as well as searching for the optimal active configuration from the relationships between ORR performance and different configurations can be realized from such a practical descriptor, which can also be extended to other nanocarbon-based metal-free electrocatalytic reactions for deeply understanding their electrocatalytic mechanisms.

A New Co-Free Ni-Rich LiNi0.8Fe0.1Mn0.1O2 Cathode for Low-Cost Li-Ion Batteries.

In recent years, with the rapid development of electric vehicles, the ever-fluctuating cobalt price has become a decisive constraint on the supply chain of the lithium-ion (Li-ion) battery industry. To address these challenges, a new and unreported cobalt-free (Co-free) material with a general formula of LiNi0.8Fe0.1Mn0.1O2 (NFM) is introduced. This Co-free material is synthesized via the coprecipitation method and examined by using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) to investigate the morphological, crystal-structure, and electrochemical properties. The NFM cathode can deliver a specific capacity of 202.6 mA h g-1 (0.1C, 3.0-4.5 V), a specific energy capacity of 798.8 W h kg-1 in material level (0.1C, 3.0-4.5 V), a reasonable rate capability, and a stable cycling performance (81.1% discharge capacity retention after 150 cycles at 10C, 3.0-4.3 V). Although the research on this subject is still in its early stage, the capability of this novel cathode material as a practical candidate for applications in next-generation Co-free lithium-ion batteries (LIBs) is highlighted in this study.

A self-reinforcing and self-healing elastomer with high strength, unprecedented toughness and room-temperature reparability.

The development of intrinsic self-healing elastomers with simultaneous high mechanical strength, toughness and room-temperature reparability remains a formidable challenge. Herein, we report a mechano-responsive strategy, known as strain induced crystallization, to address the above issue, whereby synthesized elastomers with unprecedented high mechanical performances are bestowed with room-temperature self-healing materials, achieving tensile strength, toughness and fracture energy values of 29.0 MPa, 121.8 MJ m-3 and 104.1 kJ m-2, respectively.

De Novo Design of a Robust Fluorescent Probe for Basal HClO Imaging in a Mouse Parkinson's Disease Model.

Elevated HClO gets involved in the pathogenesis of Parkinson's disease (PD). Herein, a novel fluorescent probe NUU-1 was designed and synthesized. Distinct from the general strategies, NUU-1 features two distinct HClO reactive sites, a HClO-specific reaction site and a HClO-nonspecific reactive site, which in turn endows NUU-1 with the "0 + 1 > 1" amplification effect, that thus dramatically promotes the selectivity. NUU-1 displayed a fast response rate (within 15 s), remarkable fluorescence enhancement (about 538-fold), and excellent sensitivity (LOD = 25.8 nM) in response to HClO while the remaining fluorescence silence toward other common ROS (H2O2, •OH, ONOO-, O2•-, and 1O2) even at high concentrations (up to 0.5 mM). NUU-1 allows for the imaging of both exogenous and endogenous HClO in living dopaminergic cells (SH-SY5Y). Moreover, by employing NUU-1 as the probe, the image of HClO in C. elegans and zebrafish was successfully achieved. Significantly, in the first trial, NUU-1 was successfully utilized for the brain basal HClO imaging in PD mice models and distinguished PD brain tissues from normal control, thereby holding great potential for in-depth biological applications.

A novel polymer electrolyte with high elasticity and high performance for lithium metal batteries.

A polymer electrolyte with high elasticity and high performance is prepared by IN SITU polymerization. The polymer electrolyte is amorphous and has a high ionic conductivity of 7.9 × 10-4 S cm-1 and good elasticity. The discharge capacity of Li/LiFePO4 in the 100th cycle is 133.90 mA h g-1 (0.5C, 25 °C).

Enhanced Cyclability of Cr8O21 Cathode for PEO-Based All-Solid-State Lithium-Ion Batteries by Atomic Layer Deposition of Al2O3.

Cr8O21 can be used as the cathode material in all-solid-state batteries with high energy density due to its high reversible specific capacity and high potential plateau. However, the strong oxidation of Cr8O21 leads to poor compatibility with polymer-based solid electrolytes. Herein, to improve the cycle performance of the battery, Al2O3 atomic layer deposition (ALD) coating is applied on Cr8O21 cathodes to modify the interface between the electrode and the electrolyte. X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectroscopy, etc., are used to estimate the morphology of the ALD coating and the interface reaction mechanism. The electrochemical properties of the Cr8O21 cathodes are investigated. The results show that the uniform and dense Al2O3 layer not only prevents the polyethylene oxide from oxidization but also enhances the lithium-ion transport. The 12-ALD-cycle-coated electrode with approximately 4 nm Al2O3 layer displays the optimal cycling performance, which delivers a high capacity of 260 mAh g-1 for the 125th cycle at 0.1C with a discharge-specific energy of 630 Wh kg-1.

A phenothiazine coumarin based ratiometric fluorescent probe for real-time detection of lysosomal hypochlorite in living cell and zebra fish.

Hypochlorite (ClO-), a type of reactive oxygen species (ROS), plays an essential role in complex biological systems. Real-time detection of the content and distribution of ClO- in cells or subcellular organelle is critically essential. In this paper, a lysosomal-targeted fluorescent probe, Cou-Lyso, was constructed for real-time detection of ClO- in a ratiometric manner, achieving high sensitivity with a low detection limit (0.58 µM). Upon reaction with ClO-, this probe was subjected to a significant fluorescence change from red emission (λmaxem = 610 nm) to green emission (λmaxem = 535 nm) with the ratio of I535 nm/I610 nm displaying a 76-fold enhancement from 0.04 to 3.03. The confocal imaging experiments for Cou-Lyso showed that this probe could detect ClO- in living cell and zebra fish. This probe has been successfully applied to stain lysosome and image lysosomal ClO- based on co-localization imaging experiments.

A bifunctional fluorescent probe for simultaneous detection of GSH and H2Sn (n > 1) from different channels with long-wavelength emission.

In this work, we presented a long-wavelength emission fluorescent probe DCM-Cou-SePh that can discriminatively detect glutathione (GSH) and hydrogen polysulfides (H2Sn, n > 1) from green and red emission channels, respectively. With the addition of GSH, probe DCM-Cou-SePh displayed green fluorescence emission (λex/em = 430/530 nm). In the presence of H2Sn, the probe exhibited a significant fluorescence enhancement in red channel (λex/em = 560/680 nm). We also demonstrated that this probe was suitable to quantitatively detect GSH and H2Sn with low detection limits (0.12 µM for GSH, 0.19 µM for H2Sn). Furthermore, DCM-Cou-SePh can be used for sensing endogenous GSH and H2Sn in living cells by dual-color fluorescence imaging.

Rational Design of Multicolor-Emitting Chiral Carbonized Polymer Dots for Full-Color and White Circularly Polarized Luminescence.

Light-emitting chiral carbonized polymer dots (Ch-CPDs) are attracting great interest because of their extraordinary photonic properties, but modulating their band-gap emission, especially at long wavelength, and maintaining their chiral structure to achieve multicolor, high-emission Ch-CPDs remains challenging. Reported here for the first time is the synthesis of red- and multicolor-emitting Ch-CPDs using the common precursors L-/D-tryptophan and o-phenylenediamine, and a solvothermal approach at one temperature. The quantum yield of the Ch-CPDs was between 31 % and 54 %. Supramolecular self-assembly provided multicolor-emitting Ch-CPDs showing novel circularly polarized luminescence, with the highest dissymmetric factor (glum ) of 1×10-2 . Importantly, circularly polarized white-emitting CPDs were fabricated for the first time by tuning the mixing ratio of the three colored Ch-CPDs in a gel. This strategy affords exciting opportunities for designing functional chiroptical materials.

In Situ Induced Surface Reconstruction of Single-Crystal Lithium-Ion Cathode Toward Effective Interface Compatibility.

LiNixCoyMn1-x-yO2 (x ≥ 0.5) layered oxide materials are generally considered as one of the most prospective candidates for lithium-ion battery (LIBs) cathodes due to their high specific capacity and working voltage. However, surface impurity species substantially degrade the electrochemical performance of LIBs. Herein, surface reconstruction from layered structure to disordered layer and rock-salt coherent region together with a uniform Li2CO3-dominant coating layer is first in situ constructed on the single-crystal LiNi0.5Co0.2Mn0.3O2 (NCM) material by a simple water treatment procedure. The unique surface structure is elucidated by Ar-sputtering-assisted X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (spherical aberration-corrected-scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy (HRTEM), and TEM). Meanwhile, neutron powder diffraction (NPD) indicates that the antisite defect concentration is mitigated in the treated materials. The modified samples display superior cycle stability with a capacity retention of up to 87.5% at 1C after 300 cycles, a high rate capacity of 151 mAh g-1 at 5C, an elevated temperature (45 °C) cycling property with 80% capacity retention (4.5 V), and improved full-cell performance with 91% after 250 cycles at 1C. Importantly, postmortem examination on the cycled cathodes by time-of-flight secondary-ion mass spectroscopy (TOF-SIMS), XPS, TEM, and X-ray diffractometer (XRD) pattern further demonstrate that these results are mainly attributed to the thin cathode electrolyte interface (CEI) film and low solubility of transition-metal ions. Therefore, this expedition provides an opportunity to construct an effective armor for the interface compatibility and stability of LIBs.

Favorable Electrochemical Performance of LiMn2O4/LiFePO4 Composite Electrodes Attributed to Composite Solid Electrolytes for All-Solid-State Lithium Batteries.

Li1.5Al0.5Ge1.5(PO4)3 (LAGP)-PEO composite electrolytes are unstable in LiMn2O4. In addition, the discharge platform potential (2.8 and 4.0 V) difference of LiMn2O4 is relatively large, whereas the discharge platform potential (3.5 V) of LiFePO4 is between 2.8 and 4.0 V. Thus, LiMn2O4 and LiFePO4 can be compounded together to reduce the material platform voltage difference and obtain the advantages of both materials at the same time. Here, LiMn2O4/LiFePO4 composite cathodes were applied in solid-state batteries. LAGP-PEO(LiTFSI) was used as the electrolyte. The Li/composite cathode battery using composite electrolytes has a reversible capacity of 192.8 mAh g-1 at 50 °C and 0.1 C. It possesses favorable rate performance and exhibits very good cycling stability. In addition, the composite electrolytes can prevent the further occurrence of the Jahn-Teller effect. Meanwhile, the charge-transfer resistance slightly decreases in 10 cycles. The excellent capacity retention of the battery is connected with the excellent electrochemical stability and the well-interfaced contacts of the composite electrolytes with electrodes.