A two-dimensional coordination polymer with high laccase-like activity for sensitive colorimetric detection of thiram.

In contrast to natural enzymes, nanozymes show promising advantages of low cost and high stability for analytical applications. The simple mix of L-phenylalanine (F) and Cu produces two-dimensional nanosheets of a coordination polymer with a high surface area ratio and rich exposed active sites as a novel catalyst. As the mimetic of natural laccase, this nanozyme (F-Cu) can catalyze the oxidative coupling reaction of 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP) to produce a distinct red product, thus establishing an intuitive and simple method for the detection of thiram.

High-Valence Mn MOF Inspired by Laccase Mediators Enables Versatile Nature-Mimicking Catalysis.

In nature, active Mn -ligand complexes produced by laccase catalyzed oxidation can act as the low-molecular mass, diffusible redox mediators to oxidize the phenolic substrates overcoming the limitations of natural enzymes. Learning from the metal-ligand coordination of natural functional units, high-valence Mn metal-organic framework (Mn MOF) is constructed to simulate the catalysis in natural mediator system. Benefiting from the characteristics of nanoscale size, rich metal coordination unsaturated sites, and mixed valence state dominated by Mn(III), Nano Mn(III)-TP exhibits superior laccase-mimicking activity, whose V (maximal reaction rate) is much higher than that of natural laccase.

Specific Nanodrug for Diabetic Chronic Wounds Based on Antioxidase-Mimicking MOF-818 Nanozymes.

Chronic wound is a common complication for diabetic patients, which entails substantial inconvenience, persistent pain, and significant economic burden to patients. However, current clinical treatments for diabetic chronic wounds remain unsatisfactory. A prolonged but ineffective inflammation phase in chronic wounds is the primary difference between diabetic chronic wounds and normal wounds.

A novel, environmentally friendly dual-signal water toxicity biosensor developed through the continuous release of Fe.

In this work, a novel, environmentally friendly and simple electrochemical/colorimetric water toxicity biosensor was rationally developed by the continuous release of Fe in a medium. The bioluminescent bacterium Vibrio Fischeri (V. fischeri) was used for the first time as a model bacterium to assess water toxicity for a mediated electrochemical biosensor.

Kinetically restrained oxygen reduction to hydrogen peroxide with nearly 100% selectivity.

Hydrogen peroxide has been synthesized mainly through the electrocatalytic and photocatalytic oxygen reduction reaction in recent years. Herein, we synthesize a single-atom rhodium catalyst (Rh/NC) to mimic the properties of flavoenzymes for the synthesis of hydrogen peroxide under mild conditions. Rh/NC dehydrogenates various substrates and catalyzes the reduction of oxygen to hydrogen peroxide.

Interfacial Electron Regulation of Rh Atomic Layer-Decorated SnO Heterostructures for Enhancing Electrocatalytic Nitrogen Reduction.

Ammonia (NH), which serves as a fertilizer supply, is struggling to satisfy the ever-growing population requirements over the world. The electrocatalytic nitrogen reduction to NH production is highly desired but shows the extremely poor activity and selectivity of reported electrocatalysts. In this work, we rationally design a novel Rh atomic layer-decorated SnO heterostructure catalyst through the interfacial engineering strategy, simultaneously achieving the highest NH yield rate (149 μg h mg) and Faradaic efficiency (11.

Study on simplified strategies for procedure of rapid detection of water toxicity.

In this work, a simplified procedure of detection of water toxicity based on Pt ultramicroelectrode (UME) and mixed microorganism cultured without sterilization was the first proposed. A stable Pt UME was successfully prepared with a special glass tube as insulation and support material, which was used as working electrode in the biosensor. The Pt UME exhibits the typical cyclic voltammogram (CV) of Pt UME with sigmoid shape and possesses good stability, enlarged current response and tunable dimension.

Glucose-oxidase like catalytic mechanism of noble metal nanozymes.

Au nanoparticles (NPs) have been found to be excellent glucose oxidase mimics, while the catalytic processes have rarely been studied. Here, we reveal that the process of glucose oxidation catalyzed by Au NPs is as the same as that of natural glucose oxidase, namely, a two-step reaction including the dehydrogenation of glucose and the subsequent reduction of O to HO by two electrons. Pt, Pd, Ru, Rh, and Ir NPs can also catalyze the dehydrogenation of glucose, except that O is preferably reduced to HO.

Fabrication of a Novel, Cost-Effective Double-Sided Indium Tin Oxide-Based Nanoribbon Electrode and Its Application of Acute Toxicity Detection in Water.

Microelectrode plays a crucial role in developing a rapid biosensor for detecting toxicity in water. In this study, a nanoribbon electrode (NRE) with amplified microelectrode signal was successfully prepared by electrodepositing 2-allylphenol on a double-sided indium tin oxide glass. The NRE provided a simple mean for obtaining large steady-state current response.

Coenzyme-dependent nanozymes playing dual roles in oxidase and reductase mimics with enhanced electron transport.

Although nanozymes overcome a series of shortcomings of natural enzymes, their wide applications are hampered due to their limited varieties. In this work, we propose a coenzyme-dependent nanozyme, a synergistic composite comprising zeolitic imidazolate frameworks encapsulated with polyethylenimine (PEI) and functionalized with a flavin mononucleotide (PEI/ZIF-FMN). The flavin mononucleotide (FMN) plays the role of a prosthetic group, and the positively charged NH2 groups in PEI readily provide the binding affinity to nicotinamide adenine dinucleotide (NADH), which facilitates the electron transfer from NADH to FMN and terminal electron acceptors (such as O2) with a greatly enhanced (80 times) catalytic performance.

Synthesis of low dimensional hierarchical transition metal oxides a direct deep eutectic solvent calcining method for enhanced oxygen evolution catalysis.

Transition metal oxides (TMOs) are regarded as important materials due to their wide applications in catalysis, sensors, energy storage and conversion devices owing to their advantages of facile synthesis, low cost, and high activity. Here we develop a direct deep eutectic solvent (DES) calcining method to prepare low-dimensional and highly active TMOs for the electrochemical oxygen evolution reaction (OER). Glucose monohydrate and urea can form a glucose-urea DES, which was calcined under a N2 atmosphere to produce 2D N,O-doped graphene.

Oxidase-like MOF-818 Nanozyme with High Specificity for Catalysis of Catechol Oxidation.

Despite the extensive studies of the nanozymes showing their superior properties compared to natural enzymes and traditional artificial enzymes, the development of highly specific nanozymes is still a challenge. The catechol oxidase specifically catalyzing the oxidations of -diphenol to the corresponding -quinone is important to the biosynthesis of melanin and other polyphenolic natural products. In this study, we first propose that MOF-818, containing trinuclear copper centers mimicking the active sites of natural catechol oxidase, shows efficient catechol oxidase activity with good specificity and no peroxidase-like characteristics.

An unexpected discovery of 1,4-benzoquinone as a lipophilic mediator for toxicity detection in water.

Since most toxicological risk assessments are based on individual single-species tests, there is uncertainty in extrapolating these results to ecosystem assessments. Herein, we successfully developed a mediated microbial electrochemical biosensor with mixed microorganisms for toxicity detection by microelectrode array (MEA). In order to fully mobilize all the mixed microorganisms to participate in electron transfer to amplify the current signal, 1,4-benzoquinone (BQ) was used as the lipophilic mediator to mediate the intracellular metabolic activities.

Coupling Cu with Au for enhanced electrocatalytic activity of nitrogen reduction reaction.

The electrochemical nitrogen reduction reaction (NRR) under ambient conditions is currently attracting intense attention, but it still remains a great challenge to develop highly selective and active NRR electrocatalysts. Inspired by the intrinsic NRR activity of Au, we systematically studied the synergistic enhanced effect of incorporating other transition metals into Au on its NRR activity. A general strategy was used to synthesize a series of Au-based bimetallic nanocatalysts (AuCu, AuAg, AuPd and AuRu), and the NRR catalytic performance of the as-obtained electrocatalysts was investigated in detail.

A respiration substrate-less isolation method for acute toxicity assessment.

Respiration substrate (RS)-less isolation method was developed for enhancing the sensitivity of acute toxicity assessment of heavy metal ions. RS was removed from the first step of previous isolation method, which was an effective strategy for improving acute toxicity assessment. 50% inhibiting concentration (IC) values of Cu, Cd, Zn, Hg and Ni were 0.

Bio-inspired nanozyme: a hydratase mimic in a zeolitic imidazolate framework.

Nanozymes provide comparative advantages over natural enzymes and conventional artificial enzymes for catalytic reactions. However, nanozymes are only suitable for limited types of reactions, whose catalytic principles are not yet fully revealed. Herein, a new nanozyme based on a bionic zeolitic imidazolate framework is proposed.

In situ reversible color variation of a ready-made upconversion material using the designed component of a three-state fluorescence switching system.

In recent years, upconversion materials have attracted considerable attention because of their unique physicochemical features. Numerous studies have focused on the synthesis of upconversion materials with different colors. However, an easier way to vary the upconversion colors without changing the materials' components has not been extensively studied.

Reversible regulation of CdTe quantum dots fluorescence intensity based on Prussian blue with high anti-fatigue performance.

A fluorescence switching device with excellent anti-fatigue performance based on the electrochromic material Prussian blue and fluorophore CdTe quantum dots was realized. The fluorescence switching device ultimately demonstrated a high fluorescence contrast, short response time and superior anti-fatigue property. Notably, the fluorescence contrast remains unchanged after 133 cycles.

DNA-templated silver and silver-based bimetallic clusters with remarkable and sequence-related catalytic activity toward 4-nitrophenol reduction.

Herein, we report the excellent catalytic activity of DNA-AgNCs toward 4-nitrophenol reduction and a strategy for improving their catalytic performance by forming bimetallic clusters (Ag-Pd, Ag-Au and Ag-Pt). The analogous influence of sequences on the catalytic activity of these nanoclusters is disclosed, which is quite different from their erratic fluorescence properties.

Electrochemical fabrication of nanoporous gold electrodes in a deep eutectic solvent for electrochemical detections.

Deep eutectic solvents are a class of green and sustainable solvents in chemical processes. An electrochemical method was developed to fabricate nanoporous gold electrodes by alloying and dealloying Au-Zn alloy in ZnCl2-urea deep eutectic solvent. The as-prepared active nanoporous gold electrodes facilitate the electrochemical detections of water pollutants with superior sensitivities.

Shape-Control of Pt-Ru Nanocrystals: Tuning Surface Structure for Enhanced Electrocatalytic Methanol Oxidation.

Despite the fact that both electrochemical experiments and density functional theory calculations have testified to the superior electrocatalytic activity and CO-poisoning tolerance of platinum-ruthenium (PtRu) alloy nanoparticles toward the methanol oxidation reaction (MOR), the facet-dependent electrocatalytic properties of PtRu nanoparticles are scarcely revealed because it is extremely difficult to synthesize well-defined facets-enclosed PtRu nanocrystals. Herein, we for the first time report a general synthesis of ultrathin PtRu nanocrystals with tunable morphologies (nanowires, nanorods, and nanocubes) through a one-step solvothermal approach and a systematic investigation of the structure-directing effects of different surfactants and the formation mechanism by control experiments and time-dependent studies. In addition, we utilize these {100} and {111} facets-enclosed PtRu nanocrystals as model catalysts to evaluate the electrocatalytic characteristics of the MOR on different facets.

New applications of genetically modified Pseudomonas aeruginosa for toxicity detection in water.

A novel mediator-free method based on genetically modified bacteria was developed for detecting water toxicity, where genetically modified Pseudomonas aeruginosa (GM P. aeruginosa) was selected as the biosensor strain and pyocyanin (PYO) produced by this strain was used as the indicator. The toxicity response of GM P.

One-step synthesis of ultrathin PtPb nerve-like nanowires as robust catalysts for enhanced methanol electrooxidation.

Ultrathin PtPb nerve-like nanowires (NNWs) with a diameter of only around 3.6 nm were synthesized by a one-step wet-chemical strategy, and they served as robust catalysts for greatly enhancing methanol electrooxidation both under acidic and alkaline conditions. Due to the high CO-poisoning tolerance, superior electrocatalytic activity and stability endowed by the Pt-Pb alloyed composition and the unique structure, the PtPb NNWs showed the highest specific activity of 2.

A high performance hybrid battery based on aluminum anode and LiFePO4 cathode.

A novel hybrid battery utilizing an aluminum anode, a LiFePO4 cathode and an acidic ionic liquid electrolyte based on 1-ethyl-3-methylimidazolium chloride (EMImCl) and aluminum trichloride (AlCl3) (EMImCl-AlCl3, 1-1.1 in molar ratio) with or without LiAlCl4 is proposed. The hybrid ion battery delivers an initial high capacity of 160 mA h g(-1) at a current rate of C/5.

Polymerized Ionic Networks with High Charge Density: Quasi-Solid Electrolytes in Lithium-Metal Batteries.

Polymerized ionic networks (PINs) with six ion pairs per repeating unit are synthesized by nucleophilic-substitution-mediated polymerization or radical polymerization of monomers bearing six 1-vinylimidazolium cations. PIN-based solid-like electrolytes show good ionic conductivities (up to 5.32 × 10(-3) S cm(-1) at 22°C), wide electrochemical stability windows (up to 5.