Showing papers in "Small in 2020"

Metal-Organic Frameworks for Biomedical Applications.

Abstract: Metal-organic frameworks (MOFs) are an interesting and useful class of coordination polymers, constructed from metal ion/cluster nodes and functional organic ligands through coordination bonds, and have attracted extensive research interest during the past decades. Due to the unique features of diverse compositions, facile synthesis, easy surface functionalization, high surface areas, adjustable porosity, and tunable biocompatibility, MOFs have been widely used in hydrogen/methane storage, catalysis, biological imaging and sensing, drug delivery, desalination, gas separation, magnetic and electronic devices, nonlinear optics, water vapor capture, etc. Notably, with the rapid development of synthetic methods and surface functionalization strategies, smart MOF-based nanocomposites with advanced bio-related properties have been designed and fabricated to meet the growing demands of MOF materials for biomedical applications. This work outlines the synthesis and functionalization and the recent advances of MOFs in biomedical fields, including cargo (drugs, nucleic acids, proteins, and dyes) delivery for cancer therapy, bioimaging, antimicrobial, biosensing, and biocatalysis. The prospects and challenges in the field of MOF-based biomedical materials are also discussed.

Amorphous Catalysts and Electrochemical Water Splitting: An Untold Story of Harmony.

Abstract: In the near future, sustainable energy conversion and storage will largely depend on the electrochemical splitting of water into hydrogen and oxygen. Perceiving this, countless research works focussing on the fundamentals of electrocatalysis of water splitting and on performance improvements are being reported everyday around the globe. Electrocatalysts of high activity, selectivity, and stability are anticipated as they directly determine energy- and cost efficiency of water electrolyzers. Amorphous electrocatalysts with several advantages over crystalline counterparts are found to perform better in electrocatalytic water splitting. There are plenty of studies witnessing performance enhancements in electrocatalysis of water splitting while employing amorphous materials as catalysts. The harmony between the flexibility of amorphous electrocatalysts and electrocatalysis of water splitting (both the oxygen evolution reaction [OER] and the hydrogen evolution reaction [HER]) is one of the untold and unsummarized stories in the field of electrocatalytic water splitting. This Review is devoted to comprehensively discussing the upsurge of amorphous electrocatalysts in electrochemical water splitting. In addition to that, the basics of electrocatalysis of water splitting are also elaborately introduced and the characteristics of a good electrocatalyst for OER and HER are discussed.

True Meaning of Pseudocapacitors and Their Performance Metrics: Asymmetric versus Hybrid Supercapacitors

Abstract: The development of pseudocapacitive materials for energy-oriented applications has stimulated considerable interest in recent years due to their high energy-storing capacity with high power outputs. Nevertheless, the utilization of nanosized active materials in batteries leads to fast redox kinetics due to the improved surface area and short diffusion pathways, which shifts their electrochemical signatures from battery-like to the pseudocapacitive-like behavior. As a result, it becomes challenging to distinguish "pseudocapacitive" and "battery" materials. Such misconceptions have further impacted on the final device configurations. This Review is an earnest effort to clarify the confusion between the battery and pseudocapacitive materials by providing their true meanings and correct performance metrics. A method to distinguish battery-type and pseudocapacitive materials using the electrochemical signatures and quantitative kinetics analysis is outlined. Taking solid-state supercapacitors (SSCs, only polymer gel electrolytes) as an example, the distinction between asymmetric and hybrid supercapacitors is discussed. The state-of-the-art progress in the engineering of active materials is summarized, which will guide for the development of real-pseudocapacitive energy storage systems.

Multidimension-Controllable Synthesis of MOF-Derived Co@N-Doped Carbon Composite with Magnetic-Dielectric Synergy toward Strong Microwave Absorption

Abstract: Metal-organic framework (MOF) is highly desirable as a functional material owing to its low density, tunable pore size, and diversity of coordination formation, but limited by the poor dielectric properties. Herein, by controlling the solvent and mole ratio of cobalt/linker, multidimension-controllable MOF-derived nitrogen-doped carbon materials exhibit tunable morphology from sheet-, flower-, cube-, dodecahedron- to octahedron-like. Tunable electromagnetic parameters of Co@N-doped carbon composites (Co@NC) can be obtained and the initial MOF precursor determines the distribution of carbon framework and magnetic cobalt nanoparticles. Carbonized Co@NC composites possess the following advantages: i) controllable dimension and morphology to balance the electromagnetic properties with evenly charged density distribution; ii) magnetic-carbon composites offer plenty of interfacial polarization and strong magnetic coupling network; iii) a MOF-derived dielectric carbon skeleton provides electronic transportation paths and enhances conductive dissipation. Surface-mediated magnetic coupling reflects the stray magnetic flux field, which is corroborated by the off-axis electron holography and micro-magnetic simulation. Optimized octadecahedral Co@NC sample exhibits the best microwave absorption (MA) of -53.0 dB at the thickness of 1.8 mm and broad effective frequency from 11.4 to 17.6 GHz (Ku-band). These results pave the way to fabricate high-performance MA materials with balanced electromagnetic distribution and controlled morphology.

A Corrosion-Resistant and Dendrite-Free Zinc Metal Anode in Aqueous Systems

Abstract: Rechargeable aqueous zinc (Zn) ion-based energy storage systems have been reviving recently because of their low cost and high safety merits; however, they still suffer from the problems of corrosion and dendrite growth on Zn metal anodes that cause gas generation and early battery failure Unfortunately, the corrosion problem has not received sufficient attention until now Here, it is pioneeringly demonstrated that decorating the Zn surface with a dual-functional metallic indium (In) layer, acting as both a corrosion inhibitor and a nucleating agent, is a facile but effective strategy to suppress both drastic corrosion and dendrite growth Symmetric cells assembled with the treated Zn electrodes can sustain up to 1500 h of plating/stripping cycles with an ultralow voltage hysteresis (54 mV), and a 5000 cycle-life is achieved for a prototype full cell This work will instigate the further development of aqueous metal-based energy storage systems

Galvanic Replacement Reaction Involving Core–Shell Magnetic Chains and Orientation‐Tunable Microwave Absorption Properties

Abstract: Electromagnetic (EM) wave absorption materials have attracted considerable attention because of EM wave pollution caused by the proliferation of electronic communication devices. One-dimentional (1D) structural magnetic metals have potential as EM absorption materials. However, fabricating 1D core-shell bimetallic magnetic species is a significant challenge. Herein, 1D core-shell bimetallic magnetic chains are successfully prepared through a modified galvanic replacement reaction under an external magnetic field, which could facilitate the preparation of 1D core-shell noble magnetic chains. By delicately designing the orientation of bimetallic magnetic chains in polyvinylidene fluoride, the composites reveal the decreased complex permittivity and increased permeability compared with random counterparts. Thus, elevated EM wave absorption perfromances including an optimal reflection loss of -43.5 dB and an effective bandwidth of 7.3 GHz could be achieved for the oriented Cu@Co sample. Off-axis electron holograms indicate that the augmented magnetic coupling and remarkable polarization loss primarily contribute to EM absorption in addition to the antenna effect of the 1D structure to scatter microwaves and ohmic loss of the metallic attribute. This work can serve a guide to construct 1D core-shell bimetallic magnetic nanostructures and design magnetic configuration in polymer to tune EM parameters and strengthen EM absorption properties.

Designing Advanced Catalysts for Energy Conversion Based on Urea Oxidation Reaction.

Abstract: Urea oxidation reaction (UOR) is the underlying reaction that determines the performance of modern urea-based energy conversion technologies. These technologies include electrocatalytic and photoelectrochemical urea splitting for hydrogen production and direct urea fuel cells as power engines. They have demonstrated great potentials as alternatives to current water splitting and hydrogen fuel cell systems with more favorable operating conditions and cost effectiveness. At the moment, UOR performance is mainly limited by the 6-electron transfer process. In this case, various material design and synthesis strategies have recently been reported to produce highly efficient UOR catalysts. The performance of these advanced catalysts is optimized by the modification of their structural and chemical properties, including porosity development, heterostructure construction, defect engineering, surface functionalization, and electronic structure modulation. Considering the rich progress in this field, the recent advances in the design and synthesis of UOR catalysts for urea electrolysis, photoelectrochemical urea splitting, and direct urea fuel cells are reviewed here. Particular attention is paid to those design concepts, which specifically target the characteristics of urea molecules. Moreover, challenges and prospects for the future development of urea-based energy conversion technologies and corresponding catalysts are also discussed.

A Robust Intrinsically Green Fluorescent Poly(Amidoamine) Dendrimer for Imaging and Traceable Central Nervous System Delivery in Zebrafish.

Abstract: Intrinsically fluorescent poly(amidoamine) dendrimers (IF-PAMAM) are an emerging class of versatile nanoplatforms for in vitro tracking and bio-imaging. However, limited tissue penetration of their fluorescence and interference due to auto-fluorescence arising from biological tissues limit its application in vivo. Herein, a green IF-PAMAM (FGP) dendrimer is reported and its biocompatibility, circulation, biodistribution and potential role for traceable central nervous system (CNS)-targeted delivery in zebrafish is evaluated, exploring various routes of administration. Key features of FGP include visible light excitation (488 nm), high fluorescence signal intensity, superior photostability and low interference from tissue auto-fluorescence. After intravenous injection, FGP shows excellent imaging and tracking performance in zebrafish. Further conjugating FGP with transferrin (FGP-Tf) significantly increases its penetration through the blood-brain barrier (BBB) and prolongs its circulation in the blood stream. When administering through local intratissue microinjection, including intracranial and intrathecal injection in zebrafish, both FGP and FGP-Tf exhibit excellent tissue diffusion and effective cellular uptake in the brain and spinal cord, respectively. This makes FGP/FGP-Tf attractive for in vivo tracing when transporting to the CNS is desired. The work addresses some of the major shortcomings in IF-PAMAM and provides a promising application of these probes in the development of drug delivery in the CNS.

Metal-Containing Polydopamine Nanomaterials: Catalysis, Energy, and Theranostics

Abstract: Polydopamine (PDA) is a major type of artificial melanin material with many interesting properties such as antioxidant activity, free-radical scavenging, high photothermal conversion efficiency, and strong metal-ion chelation. The high affinity of PDA to a wide range of metals/metal ions has offered a new class of functional metal-containing polydopamine (MPDA) nanomaterials with promising functions and extensive applications. Understanding and controlling the metal coordination environment is vital to achieve desirable functions for which such materials can be exploited. MPDA nanomaterials with metal/metal ions as the active functions are reviewed, including their synthesis and metal coordination environment and their applications in catalysis, batteries, solar cells, capacitors, medical imaging, cancer therapy, antifouling, and antibacterial coating. The current trends, limitations, and future directions of this area are also explored.

H+‐Insertion Boosted α‐MnO2 for an Aqueous Zn‐Ion Battery

Abstract: Rechargeable Zn/MnO2 batteries using mild aqueous electrolytes are attracting extensive attention due to their low cost, high safety, and environmental friendliness. However, the charge-storage mechanism involved remains a topic of controversy so far. Also, the practical energy density and cycling stability are still major issues for their applications. Herein, a free-standing α-MnO2 cathode for aqueous zinc-ion batteries (ZIBs) is directly constructed with ultralong nanowires, leading to a rather high energy density of 384 mWh g-1 for the entire electrode. Greatly, the H+ /Zn2+ coinsertion mechanism of α-MnO2 cathode for aqueous ZIBs is confirmed by a combined analysis of in situ X-ray diffractometry, ex situ transmission electron microscopy, and electrochemical methods. More interestingly, the Zn2+ -insertion is found to be less reversible than H+ -insertion in view of the dramatic capacity fading occurring in the Zn2+ -insertion step, which is further evidenced by the discovery of an irreversible ZnMn2 O4 layer at the surface of α-MnO2 . Hence, the H+ -insertion process actually plays a crucial role in maintaining the cycling performance of the aqueous Zn/α-MnO2 battery. This work is believed to provide an insight into the charge-storage mechanism of α-MnO2 in aqueous systems and paves the way for designing aqueous ZIBs with high energy density and long-term cycling ability.

In Situ Grown Single-Atom Cobalt on Polymeric Carbon Nitride with Bidentate Ligand for Efficient Photocatalytic Degradation of Refractory Antibiotics

Abstract: Semiconductor photocatalysis is a promising technology to tackle refractory antibiotics contamination in water. Herein, a facile in situ growth strategy is developed to implant single-atom cobalt in polymeric carbon nitride (pCN) via the bidentate ligand for efficient photocatalytic degradation of oxytetracycline (OTC). The atomic characterizations indicate that single-atom cobalt is successfully anchored on pCN by covalently forming the CoO bond and CoN bond, which will strengthen the interaction between single-atom cobalt and pCN. This single-atom cobalt can efficiently expand optical absorption, increase electron density, facilitate charge separation and transfer, and promote OTC degradation. As the optimal sample, Co(1.28%)pCN presents an outstanding apparent rate constant for OTC degradation (0.038 min-1 ) under visible light irradiation, which is about 3.7 times than that of the pristine pCN. The electron spin resonance (ESR) tests and reactive species trapping experiments demonstrate that the 1 O2 , h+ , •O2 - , and •OH are responsible for OTC degradation. This work develops a new way to construct single-atom-modified pCN and provides a green and highly efficient strategy for refractory antibiotics removal.

Tunable and Ultraefficient Microwave Absorption Properties of Trace N-Doped Two-Dimensional Carbon-Based Nanocomposites Loaded with Multi-Rare Earth Oxides

Abstract: A high efficiency and great tunability of bandwidth and absorption-range electromagnetic wave absorber is proposed without precedent. A series of 2D carbon-based nanocomposites with the loading of cerium oxide (CN-Ce) and other types of rare earth oxides (CN-REOs) can be successfully synthesized by a simple solvothermal-sintering method. As-synthesized 2D nanocomposites with local graphite-like C3 N4 structure and trace N-doped are identified by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. The CN-REOs and polyvinylidene fluoride composite absorbers with reflection loss values above -40 dB are obtained in C-band, X-band, and Ku-band, respectively. The empirical rules on effective bandwidth and frequency range are discovered and summarized, which can be successfully realized by simply tuning the doping amount or type of REO. The mechanism is explained by enhanced attenuation and tunable impedance matching. In addition co-filled samples by two types of CN-REOs nanocomposites are prepared to support these findings and inspire the preparation of absorber with desirable frequency band in the range of 2-18 GHz.

Co-Induced Electronic Optimization of Hierarchical NiFe LDH for Oxygen Evolution.

Abstract: Developing efficient and stable non-noble electrocatalysts for the oxygen evolution reaction (OER) remains challenging for practical applications While nickel-iron layered double hydroxides (NiFe-LDH) are emerging as prominent candidates with promising OER activity, their catalytic performance is still restricted by the limited active sites, poor conductivity and durability Herein, hierarchical nickel-iron-cobalt LDH nanosheets/carbon fibers (NiFeCo-LDH/CF) are synthesized through solvent-thermal treatment of ZIF-67/CF Extended X-ray adsorption fine structure analyses reveal that the Co substitution can stabilize the Fe local coordination environment and facilitate the π-symmetry bonding orbital in NiFeCo-LDH/CF, thus modifying the electronic structures Coupling with the structural advantages, including the largely exposed active surface sites and facilitated charge transfer pathway ensured by CF, the resultant NiFeCo-LDH/CF exhibits excellent OER activity with an overpotential of 249 mV at 10 mA cm-1 as well as robust stability over 20 h

Platelet Membrane-Camouflaged Magnetic Nanoparticles for Ferroptosis-Enhanced Cancer Immunotherapy.

Abstract: Although cancer immunotherapy has emerged as a tremendously promising cancer therapy method, it remains effective only for several cancers. Photoimmunotherapy (e.g., photodynamic/photothermal therapy) could synergistically enhance the immune response of immunotherapy. However, excessively generated immunogenicity will cause serious inflammatory response syndrome. Herein, biomimetic magnetic nanoparticles, Fe3 O4 -SAS @ PLT, are reported as a novel approach to sensitize effective ferroptosis and generate mild immunogenicity, enhancing the response rate of non-inflamed tumors for cancer immunotherapy. Fe3 O4 -SAS@PLT are built from sulfasalazine (SAS)-loaded mesoporous magnetic nanoparticles (Fe3 O4 ) and platelet (PLT) membrane camouflage and triggered a ferroptotic cell death via inhibiting the glutamate-cystine antiporter system Xc - pathway. Fe3 O4 -SAS @ PLT-mediated ferroptosis significantly improves the efficacy of programmed cell death 1 immune checkpoint blockade therapy and achieves a continuous tumor elimination in a mouse model of 4T1 metastatic tumors. Proteomics studies reveal that Fe3 O4 -SAS @ PLT-mediated ferroptosis could not only induce tumor-specific immune response but also efficiently repolarize macrophages from immunosuppressive M2 phenotype to antitumor M1 phenotype. Therefore, the concomitant of Fe3 O4 -SAS @ PLT-mediated ferroptosis with immunotherapy are expected to provide great potential in the clinical treatment of tumor metastasis.

Structural Color Materials for Optical Anticounterfeiting

Abstract: The counterfeiting of goods is growing worldwide, affecting practically any marketable item ranging from consumer goods to human health. Anticounterfeiting is essential for authentication, currency, and security. Anticounterfeiting tags based on structural color materials have enjoyed worldwide and long-term commercial success due to their inexpensive production and exceptional ease of percept. However, conventional anticounterfeiting tags of holographic gratings can be readily copied or imitated. Much progress has been made recently to overcome this limitation by employing sufficient complexity and stimuli-responsive ability into the structural color materials. Moreover, traditional processing methods of structural color tags are mainly based on photolithography and nanoimprinting, while new processing methods such as the inkless printing and additive manufacturing have been developed, enabling massive scale up fabrication of novel structural color security engineering. This review presents recent breakthroughs in structural color materials, and their applications in optical encryption and anticounterfeiting are discussed in detail. Special attention is given to the unique structures for optical anticounterfeiting techniques and their optical aspects for encryption. Finally, emerging research directions and current challenges in optical encryption technologies using structural color materials is presented.

2D Metal–Organic Frameworks (MOFs) for High‐Performance BatCap Hybrid Devices

Abstract: Two identical layered metal-organic frameworks (MOFs) (CoFRS and NiFRS) are constructed by using flexible 1,10-bis(1,2,4-triazol-1-yl)decane as pillars and 1,4-benzenedicarboxylic acid as rigid linkers The single-crystal structure analysis indicates that the as-synthesized MOFs possess fluctuant 2D networks with large interlayer lattices Serving as active electrode elements in supercapacitors, both MOFs deliver excellent rate capabilities, high capacities, and longstanding endurances Moreover, the new intermediates in two electrodes before and after long-lifespan cycling are also examined, which cannot be identified as metal hydroxides in the peer reports After assembled into battery-supercapacitor (BatCap) hybrid devices, the NiFRS//activated carbon (AC) device displays better electrochemical results in terms of gravimetric capacitance and cycling performance than CoFRS//AC devices, and a higher energy-density value of 287 Wh kg-1 compared to other peer references with MOFs-based electrodes Furthermore, the possible factors to support the distinct performances are discussed and analyzed

Recent Progress in Metal‐Free Covalent Organic Frameworks as Heterogeneous Catalysts

Abstract: Covalent organic frameworks (COFs), connecting different organic units into one system through covalent bonds, are crystalline organic porous materials with 2D or 3D networks. Compared with conventional porous materials such as inorganic zeolite, active carbon, and metal-organic frameworks, COFs are a new type of porous materials with well-designed pore structure, high surface area, outstanding stability, and easy functionalization at the molecular level, which have attracted extensive attention in various fields, such as energy storage, gas separation, sensing, photoluminescence, proton conduction, magnetic properties, drug delivery, and heterogeneous catalysis. Herein, the recent advances in metal-free COFs as a versatile platform for heterogeneous catalysis in a wide range of chemical reactions are presented and the synthetic strategy and promising catalytic applications of COF-based catalysts (including photocatalysis) are summarized. According to the types of catalytic reactions, this review is divided into the following five parts for discussion: achiral organic catalysis, chiral organic conversion, photocatalytic organic reactions, photocatalytic energy conversion (including water splitting and the reduction of carbon dioxide), and photocatalytic pollutant degradation. Furthermore, the remaining challenges and prospects of COFs as heterogeneous catalysts are also presented.

An Ultrafast Conducting Polymer@MXene Positive Electrode with High Volumetric Capacitance for Advanced Asymmetric Supercapacitors

Abstract: Pseudocapacitors or redox capacitors that synergize the merits of batteries and double-layer capacitors are among the most promising candidates for high-energy and high-power energy storage applications. 2D transition metal carbides (MXenes), an emerging family of pseudocapacitive materials with ultrahigh rate capability and volumetric capacitance, have attracted much interest in recent years. However, MXenes have only been used as negative electrodes as they are easily oxidized at positive (anodic) potential. To construct a high-performance MXene-based asymmetric device, a positive electrode with a compatible performance is highly desired. Herein, an ultrafast polyaniline@MXene cathode prepared by casting a homogenous polyaniline layer onto a 3D porous Ti3 C2 Tx MXene is reported, which enables the stable operation of MXene at positive potentials because of the enlarged work function after compositing with polyaniline, according to the first-principle calculations. The resulting flexible polyaniline@MXene positive electrode demonstrates a high volumetric capacitance of 1632 F cm-3 and an ultrahigh rate capability with 827 F cm-3 at 5000 mV s-1 , surpassing all reported positive electrodes. An asymmetric device is further fabricated with MXene as the anode and polyaniline@MXene as the cathode, which delivers a high energy density of 50.6 Wh L-1 and an ultrahigh power density of 127 kW L-1 .

Recent Advances in Functionalized Carbon Dots toward the Design of Efficient Materials for Sensing and Catalysis Applications

Abstract: Since the past decade, enormous research efforts have been devoted to the detection/degradation and quantification of environmental toxic pollutants and biologically important molecules due to their ubiquitous necessity in the fields of environmental protection and human health. These fields of sensor and catalysis are advanced to a new era after emerging of nanomaterials, especially, carbon nanomaterials including graphene, carbon nanotube, carbon dots (C-dots), etc. Among them, the C-dots in the carbon family are rapidly boosted in the aspect of synthesis and application due to their superior properties of chemical and photostability, highly fluorescent with tunable, non/low-toxicity, and biocompatibility. The C-dot-based functional materials have shown great potential in sensor and catalysis fields for the detection/degradation of environmental pollutants. The major advantage of C-dots is that they can be easily prepared from numerous biomass/waste materials which are inexpensive and environment-friendly and are suitable for a developing trend of sustainable materials. This review is devoted to the recent development (since 2017) in the synthesis of biomass- and chemical-derived C-dots as well as diverse functionalization of C-dots. Their capability as a sensor and catalyst and respective mechanism are summarized. The future perspectives of C-dots are also discussed.

Spatially Separating Redox Centers on Z‐Scheme ZnIn 2 S 4 /BiVO 4 Hierarchical Heterostructure for Highly Efficient Photocatalytic Hydrogen Evolution

Abstract: Photocatalysis technology using solar energy for hydrogen (H2 ) production still faces great challenges to design and synthesize highly efficient photocatalysts, which should realize the precise regulation of reactive sites, rapid migration of photoinduced carriers and strong visible light harvest. Here, a facile hierarchical Z-scheme system with ZnIn2 S4 /BiVO4 heterojunction is proposed, which can precisely regulate redox centers at the ZnIn2 S4 /BiVO4 hetero-interface by accelerating the separation and migration of photoinduced charges, and then enhance the oxidation and reduction ability of holes and electrons, respectively. Therefore, the ZnIn2 S4 /BiVO4 heterojunction exhibits excellent photocatalytic performance with a much higher H2 -evolution rate of 5.944 mmol g-1 h-1 , which is about five times higher than that of pure ZnIn2 S4 . Moreover, this heterojunction shows good stability and recycle ability, providing a promising photocatalyst for efficient H2 production and a new strategy for the manufacture of remarkable photocatalytic materials.

Multifunctional Antimicrobial Biometallohydrogels Based on Amino Acid Coordinated Self-Assembly.

Abstract: There is a real need for new antibiotics against self-evolving bacteria. One option is to use biofriendly broad-spectrum and mechanically tunable antimicrobial hydrogels that can combat multidrug-resistant microbes. Whilst appealing, there are currently limited options. Herein, broad-spectrum antimicrobial biometallohydrogels based on the self-assembly and local mineralization of Ag+ -coordinated Fmoc-amino acids are reported. Such biometallohydrogels have the advantages of localized delivery and sustained release, reduced drug dosage and toxicity yet improved bioavailability, prolonged drug effect, and tunable mechanical strength. Furthermore, they can directly interact with the cell walls and membrane, resulting in the detachment of the plasma membrane and leakage of the cytoplasm. This leads to cell death, triggering a significant antibacterial effect against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria in cells and mice. This study paves the way for developing a multifunctional integration platform based on simple biomolecules coordinated self-assembly toward a broad range of biomedical applications.

An Overview and Future Perspectives of Rechargeable Zinc Batteries.

Abstract: Aqueous rechargeable zinc-based batteries have sparked a lot of enthusiasm in the energy storage field recently due to their inherent safety, low cost, and environmental friendliness. Although remarkable progress has been made in the exploration of performance so far, there are still many challenges such as low working voltage and dissolution of electrode materials at the material and system level. Herein, the central tenet is to establish a systematic summary for the construction and mechanism of different aqueous zinc-based batteries. Details for three major zinc-based battery systems, including alkaline rechargeable Zn-based batteries (ARZBs), aqueous Zn ion batteries (AZIBs), and dual-ion hybrid Zn batteries (DHZBs) are given. First, the electrode materials and energy storage mechanism of the three types of zinc-based batteries are discussed to provide universal guidance for these batteries. Then, the electrode behavior of zinc anodes and strategies to deal with problems such as dendrite and passivation are recommended. Finally, some challenge-oriented solutions are provided to facilitate the next development of zinc-based batteries. Combining the characteristics of zinc-based batteries with good use of concepts and ideas from other disciplines will surely pave the way for its commercialization.

Progress in Microfluidics-Based Exosome Separation and Detection Technologies for Diagnostic Applications.

Abstract: Exosomes are secreted by most cell types and circulate in body fluids. Recent studies have revealed that exosomes play a significant role in intercellular communication and are closely associated with the pathogenesis of disease. Therefore, exosomes are considered promising biomarkers for disease diagnosis. However, exosomes are always mixed with other components of body fluids. Consequently, separation methods for exosomes that allow high-purity and high-throughput separation with a high recovery rate and detection techniques for exosomes that are rapid, highly sensitive, highly specific, and have a low detection limit are indispensable for diagnostic applications. For decades, many exosome separation and detection techniques have been developed to achieve the aforementioned goals. However, in most cases, these two techniques are performed separately, which increases operation complexity, time consumption, and cost. The emergence of microfluidics offers a promising way to integrate exosome separation and detection functions into a single chip. Herein, an overview of conventional and microfluidics-based techniques for exosome separation and detection is presented. Moreover, the advantages and drawbacks of these techniques are compared.

Nanopore Targeted Sequencing for the Accurate and Comprehensive Detection of SARS-CoV-2 and Other Respiratory Viruses.

Abstract: The ongoing global novel coronavirus pneumonia COVID-19 outbreak has engendered numerous cases of infection and death COVID-19 diagnosis relies upon nucleic acid detection; however, currently recommended methods exhibit high false-negative rates and are unable to identify other respiratory virus infections, thereby resulting in patient misdiagnosis and impeding epidemic containment Combining the advantages of targeted amplification and long-read, real-time nanopore sequencing, herein, nanopore targeted sequencing (NTS) is developed to detect SARS-CoV-2 and other respiratory viruses simultaneously within 6-10 h, with a limit of detection of ten standard plasmid copies per reaction Compared with its specificity for five common respiratory viruses, the specificity of NTS for SARS-CoV-2 reaches 100% Parallel testing with approved real-time reverse transcription-polymerase chain reaction kits for SARS-CoV-2 and NTS using 61 nucleic acid samples from suspected COVID-19 cases show that NTS identifies more infected patients (22/61) as positive, while also effectively monitoring for mutated nucleic acid sequences, categorizing types of SARS-CoV-2, and detecting other respiratory viruses in the test sample NTS is thus suitable for COVID-19 diagnosis; moreover, this platform can be further extended for diagnosing other viruses and pathogens

Single Ni Atoms Anchored on Porous Few‐Layer g‐C 3 N 4 for Photocatalytic CO 2 Reduction: The Role of Edge Confinement

Abstract: It is greatly intriguing yet remains challenging to construct single-atomic photocatalysts with stable surface free energy, favorable for well-defined atomic coordination and photocatalytic carrier mobility during the photoredox process. Herein, an unsaturated edge confinement strategy is defined by coordinating single-atomic-site Ni on the bottom-up synthesized porous few-layer g-C3 N4 (namely, Ni5 -CN) via a self-limiting method. This Ni5 -CN system with a few isolated Ni clusters distributed on the edge of g-C3 N4 is beneficial to immobilize the nonedged single-atomic-site Ni species, thus achieving a high single-atomic active site density. Remarkably, the Ni5 -CN system exhibits comparably high photocatalytic activity for CO2 reduction, giving the CO generation rate of 8.6 µmol g-1 h-1 under visible-light illumination, which is 7.8 times that of pure porous few-layer g-C3 N4 (namely, CN, 1.1 µmol g-1 h-1 ). X-ray absorption spectrometric analysis unveils that the cationic coordination environment of single-atomic-site Ni center, which is formed by Ni-N doping-intercalation the first coordination shell, motivates the superiority in synergistic N-Ni-N connection and interfacial carrier transfer. The photocatalytic mechanistic prediction confirms that the introduced unsaturated Ni-N coordination favorably binds with CO2 , and enhances the rate-determining step of intermediates for CO generation.

Zn2+ Pre-Intercalation Stabilizes the Tunnel Structure of MnO2 Nanowires and Enables Zinc-Ion Hybrid Supercapacitor of Battery-Level Energy Density.

Abstract: Although there has been tremendous progress in exploring new configurations of zinc-ion hybrid supercapacitors (Zn-HSCs) recently, the much lower energy density, especially the much lower areal energy density compared with that of the rechargeable battery, is still the bottleneck, which is impeding their wide applications in wearable devices. Herein, the pre-intercalation of Zn which gives rise to a highly stable tunnel structure of ZnMnO in nanowire form that are grown on flexible carbon cloth with a disruptively large mass loading of 12 mg cm is reported. More interestingly, the ZnMnO nanowires of tunnel structure enable an ultrahigh areal energy density and power density, when they are employed as the cathode in Zn-HSCs. The achieved areal capacitance of up to 1745.8 mF cm at 2 mA cm, and the remarkable areal energy density of 969.9 µWh cm are comparable favorably with those of Zn-ion batteries. When integrated into a quasi-solid-state device, they also endow outstanding mechanical flexibility. The truly battery-level Zn-HSCs are timely in filling up of the battery-supercapacitor gap, and promise applications in the new generation flexible and wearable devices.

Crosslinking Strategies for 3D Bioprinting of Polymeric Hydrogels

Abstract: Three-dimensional (3D) bioprinting has recently advanced as an important tool to produce viable constructs that can be used for regenerative purposes or as tissue models. To develop biomimetic and sustainable 3D constructs, several important processing aspects need to be considered, among which crosslinking is most important for achieving desirable biomechanical stability of printed structures, which is reflected in subsequent behavior and use of these constructs. In this work, crosslinking methods used in 3D bioprinting studies are reviewed, parameters that affect bioink chemistry are discussed, and the potential toward improving crosslinking outcomes and construct performance is highlighted. Furthermore, current challenges and future prospects are discussed. Due to the direct connection between crosslinking methods and properties of 3D bioprinted structures, this Review can provide a basis for developing necessary modifications to the design and manufacturing process of advanced tissue-like constructs in future.

An Efficient Cobalt Phosphide Electrocatalyst Derived from Cobalt Phosphonate Complex for All-pH Hydrogen Evolution Reaction and Overall Water Splitting in Alkaline Solution.

Abstract: The development of low-cost and highly efficient electrocatalysts via an eco-friendly synthetic method is of great significance for future renewable energy storage and conversion systems. Herein, cobalt phosphides confined in porous P-doped carbon materials (Co-P@PC) are fabricated by calcinating the cobalt-phosphonate complex formed between 1-hydroxyethylidenediphosphonic acid and Co(NO3 )2 in alkaline solution. The P-containing ligand in the complex acts as the carbon source as well as in situ phosphorizing agent for the formation of cobalt phosphides and doping P element into carbon material upon calcination. The Co-P@PC exhibits high activity for all-pH hydrogen evolution reaction (overpotentials of 72, 85, and 76 mV in acidic, neutral, and alkaline solutions at the current density of 10 mA cm-2 ) and oxygen evolution reaction in alkaline solution (an overpotential of 280 mV at the current density of 10 mA cm-2 ). The alkaline electrolyzer assembled from the Co-P@PC electrodes delivers the current density of 10 mA cm-2 at the voltage of 1.60 V with a durability of 60 h. The excellent activity and long-term stability of the Co-P@PC derives from the synergistic effect between the active cobalt phosphides and the porous P-doped carbon matrix.

A Glucose/Oxygen‐Exhausting Nanoreactor for Starvation‐ and Hypoxia‐Activated Sustainable and Cascade Chemo‐Chemodynamic Therapy

Abstract: Fenton reaction-mediated chemodynamic therapy (CDT) can kill cancer cells via the conversion of H2 O2 to highly toxic HO•. However, problems such as insufficient H2 O2 levels in the tumor tissue and low Fenton reaction efficiency severely limit the performance of CDT. Here, the prodrug tirapazamine (TPZ)-loaded human serum albumin (HSA)-glucose oxidase (GOx) mixture is prepared and modified with a metal-polyphenol network composed of ferric ions (Fe3+ ) and tannic acid (TA), to obtain a self-amplified nanoreactor termed HSA-GOx-TPZ-Fe3+ -TA (HGTFT) for sustainable and cascade cancer therapy with exogenous H2 O2 production and TA-accelerated Fe3+ /Fe2+ conversion. The HGTFT nanoreactor can efficiently convert oxygen into HO• for CDT, consume glucose for starvation therapy, and provide a hypoxic environment for TPZ radical-mediated chemotherapy. Besides, it is revealed that the nanoreactor can significantly elevate the intracellular reactive oxygen species content and hypoxia level, decrease the intracellular glutathione content, and release metal ions in the tumors for metal ion interference therapy (also termed "ion-interference therapy" or "metal ion therapy"). Further, the nanoreactor can also increase the tumor's hypoxia level and efficiently inhibit tumor growth. It is believed that this tumor microenvironment-regulable nanoreactor with sustainable and cascade anticancer performance and excellent biosafety represents an advance in nanomedicine.

Recent Progress on NiFe-Based Electrocatalysts for the Oxygen Evolution Reaction.

Abstract: The seriousness of the energy crisis and the environmental impact of global anthropogenic activities have led to an urgent need to develop efficient and green fuels. Hydrogen, as a promising alternative resource that is produced in an environmentally friendly and sustainable manner by a water splitting reaction, has attracted extensive attention in recent years. However, the large-scale application of water splitting devices is hindered predominantly by the sluggish oxygen evolution reaction (OER) at the anode. Therefore, the design and exploration of high-performing OER electrocatalysts is a critical objective. Considering their low prices, abundant reserves, and intrinsic activities, NiFe-based bimetal compounds are widely studied as excellent OER electrocatalysts. Moreover, recent progress on NiFe-based OER electrocatalysts in alkaline environments is comprehensively and systematically introduced through various catalyst families including NiFe-layered hydroxides, metal-organic frameworks, NiFe-based (oxy)hydroxides, NiFe-based oxides, NiFe alloys, and NiFe-based nonoxides. This review briefly introduces the advanced NiFe-based OER materials and their corresponding reaction mechanisms. Finally, the challenges inherent to and possible strategies for producing extraordinary NiFe-based electrocatalysts are discussed.