n/a

Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

Nanoplatelets (NPLs) share excellent luminescent properties with their symmetric quantum dots counterparts and entail special characters benefiting from the shape, like the thickness-dependent bandgap and anisotropic luminescence. However, perovskite NPLs, especially those based on iodide, suffer from poor spectral and phase stability. Here, stable CsPbI3 NPLs obtained by accelerating the crystallization process in ambient-condition synthesis are reported. By this kinetic control, the rectangular NPLs into quasi-square NPLs are tuned, where enlarged width endows the NPLs with a lower surface-area-to-volume ratio (S/V ratio), leading to lower surficial energy and thus improved endurance against NPL fusion (cause for spectral shift or phase transformation). The accelerated crystallization, denoting the fast nucleation and short period of growth in this report, is enabled by preparing a precursor with complete transformation of PbI2 into intermediates (PbI3-), through an additional iodide supplier (e.g., zinc iodide). The excellent color stability of the materials remains in the light-emitting diodes under various bias stresses.

Transition-metal oxides (TMOs) are potential candidates for anode materials of lithium-ion batteries (LIBs) due to their high theoretical capacity (similar to 1000 mA h/g) and enhanced safety from suppressing the formation of lithium dendrites. However, the poor electron conductivity and the large volume expansion during lithiation/delithiation processes are still the main hurdles for the practical usage of TMOs as anode materials. In this work, the CoSnO3@NC@ MnO@NC hierarchical nanobox (CNMN) is then proposed and fabricated to solve those issues. The as-prepared nanobox contains hollow cubic CoSnO3 as a core and dual N-doped carbon-"sandwiched" MnO particles as a shell. As anode materials of LIBs, the hollow and carbon interlayer structures effectively accommodate the volume expansion while dual active TMOs of CoSnO3 and Notably, the dual-layer structure of N-doped carbons plays a critical functional role MnO efficiently increase the specific capacity. in the incorporated composites, where the inner layer serves as a reaction substrate and a spatial barrier and the outer layer offers electron conductivity, enabling more effective involvement of active anode materials in lithium storage, as well as maintaining their high activity during lithium cycling. Subsequently, the as-prepared CNMN exhibits a high specific capacity of 1195 mA h/g after the 200th cycle at 0.1C and an excellent stable reversible capacity of about 876 mA h/g after the 300th cycle at 0.5C with only 0.07 mA h/g fade per cycle after 300 cycles. Even after a 250 times fast charging/discharging cycle both at SC, it still retains a reversible capacity of 422.6 mA h/g. We ascribe the enhanced lithium storage performances to the novel hierarchical architectures achieved from the rational design.

Electrochemical splitting of water is one of the most reliable and effective ways for the sustainable production of pure hydrogen on a large scale, while the core of this technology lies in the development of highly active non-noble-metal-based electrocatalysts to lower the large dynamic overpotentials of electrode materials. Here, an interface engineering strategy is demonstrated to construct an efficient and stable catalyst based on NiS@MoS2 core-shell hierarchical microspheres for the hydrogen evolution reactions (HER). The ultrathin MoS2 nanosheets in-situ grow on the surface of NiS hierarchical micro-sized spheres constructed by porous nanoplates, endowing the composites with rich interfaces, well-exposed electroactive edges, high structural porosity and fast transport channels. These advantages are favorable for the improvement of catalytic sites and the transport of catalysis-relevant species. More importantly, the intimate contact between MoS2 nanosheets and NiS nanoplates synergistically favors the chemical sorption of hydrogen intermediates, thereby reducing the reaction barrier and accelerating the HER catalytic process. As a result, the optimized NiS@MoS2 catalyst manifests impressive HER activity and durability, with a low overpotential of 208 mV in 0.5 M H2SO4 and 146 mV in 1.0 M KOH at 10 mA cm(-2), respectively. This work not only provides an effective way to construct core-shell hierarchical microspheres but also a multiscale strategy to regulate the electronic structure of heterostructured materials for energy-related applications. (C) 2020 Elsevier B.V. All rights reserved.

Hollow heterostructures have tremendous advantages in electrochemical energy storage and conversion areas due to their unique structure and composition characteristics. Here, we report the controlled synthesis of hollow CoSe2 nanocubes decorated with ultrathin MoSe2 nanosheets (CoSe2@MoSe2) as an efficient and robust bifunctional electrocatalyst for overall water splitting in a wide pH range. It is found that integrating ultrathin MoS2 nanosheets with hollow CoSe2 nanocubes can provide abundant active sites, promote electron/mass transfer and bubble release and facilitate the migration of charge carriers. Additionally, the surface electron coupling in the heterostructures enables it to serve as a source of sites for H+ and/or OH- adsorption, thus reducing the activation barrier for water molecules adsorption and dissociation. As a result, the title compound, CoSe2@MoSe2 hollow heterostructures, exhibits an overpotential of 183 mV and 309 mV at a current density of 10 mA cm(-2) toward hydrogen evolution reactions and oxygen evolution reactions in 1.0 M KOH, respectively. When applied as both cathode and anode for overall water splitting, a low battery voltage of 1.524 V is achieved along with excellent stability for at least 12 h. This work provides a new idea for the design and synthesis of high-performance catalysts for electrochemical energy storage and conversion.

Metal oxides have a large storage capacity when employed as anode materials for lithium-ion batteries (LIBs). However, they often suffer from poor capacity retention due to their low electrical conductivity and huge volume variation during the charge-discharge process. To overcome these limitations, fabrication of metal oxides/carbon hybrids with hollow structures can be expected to further improve their electrochemical properties. Herein, ZnO-Co3O4 nanocomposites embedded in N-doped carbon (ZnO-Co3O4@N-C) nanocages with hollow dodecahedral shapes have been prepared successfully by the simple carbonizing and oxidizing of metal-organic frameworks (MOFs). Benefiting from the advantages of the structural features, i.e. the conductive N-doped carbon coating, the porous structure of the nanocages and the synergistic effects of different components, the as-prepared ZnO-Co3O4@N-C not only avoids particle aggregation and nanostructure cracking but also facilitates the transport of ions and electrons. As a result, the resultant ZnO-Co3O4@N-C shows a discharge capacity of 2373 mAh g(-1) at the first cycle and exhibits a retention capacity of 1305 mAh g(-1) even after 300 cycles at 0.1 A g(-1). In addition, a reversible capacity of 948 mAh g(-1) is obtained at a current density of 2 A g(-1), which delivers an excellent high-rate cycle ability.

We describe a method for magnetic solid phase extraction of trace-levels of Hg(II) ions by using Fe3O4 nanoparticles (NPs) covered with a shell of silica and modified with the chelator N-(2-acetylaminoethyl)-N-(3-triethoxysilylpropyl)thiourea. The new magnetic NPs enable rapid magnetic separation, thus leading to higher efficiency and accuracy. The extracted Hg(II) ions on the NPs were directly quantified using a mercury analyzer. Possible interferents are widely eliminated in this highly selective extraction process, and the NPs are not exerting an interfering effect either. The method has an enrichment factor of 100, and extraction recoveries are between 95 and 107 % when using 10 mg of the extracting NPs. The method works over a wide range of pH values and can be applied to even complex natural samples. The effects of pH value, extraction time, sample volume and adsorbent amount on the extraction efficiency were optimized. Under the optimal conditions, the detection limit is as low as 17 ng L-1. The method was applied to the preconcentration and detection of Hg(II) in three natural water samples using the standard addition method.

As one of the major causes of antimicrobial resistance, beta-lactamase develops rapidly among bacteria. Detection of beta-lactamase in an efficient and low-cost point-of-care testing (POCT) way is urgently needed. However, due to the volatile environmental factors, the quantitative measurement of current POCT is often inaccurate. Herein, we demonstrate an artificial intelligence (AI)-assisted mobile health system that consists of a paper-based beta-lactamase fluorogenic probe analytical device and a smartphone-based AI cloud. An ultrafast broad-spectrum fluorogenic probe (B1) that could respond to beta-lactamase within 20 s was first synthesized, and the detection limit was determined to be 0.13 nmol/L. Meanwhile, a three-dimensional microfluidic paper-based analytical device was fabricated for integration of B1. Also, a smartphone-based AI cloud was developed to correct errors automatically and output results intelligently. This smart system could calibrate the temperature and pH in the beta-lactamase level detection in complex samples and mice infected with various bacteria, which shows the problem-solving ability in interdisciplinary research, and demonstrates potential clinical benefits.

The chelating gadolinium-complex is routinely used as magnetic resonance imaging (MRI) -contrast enhancer. However, several safety issues have recently been reported by FDA and PRAC. There is an urgent need for the next generation of safer MRI-contrast enhancers, with improved local contrast and targeting capabilities. Cerium oxide nanoparticles (CeNPs) are designed with fractions of up to 50% gadolinium to utilize the superior MRI-contrast properties of gadolinium. CeNPs are well-tolerated in vivo and have redox properties making them suitable for biomedical applications, for example scavenging purposes on the tissue-and cellular level and during tumor treatment to reduce in vivo inflammatory processes. Our near edge X-ray absorption fine structure (NEXAFS) studies show that implementation of gadolinium changes the initial co-existence of oxidation states Ce3+ and Ce4+ of cerium, thereby affecting the scavenging properties of the nanoparticles. Based on ab initio electronic structure calculations, we describe the most prominent spectral features for the respective oxidation states. The as-prepared gadolinium-implemented CeNPs are 3-5 nm in size, have r(1)-relaxivities between 7-13 mM(-1) s(-1) and show clear antioxidative properties, all of which means they are promising theranostic agents for use in future biomedical applications.

Gadolinium chelates are employed worldwide today as clinical contrast agents for magnetic resonance imaging. Until now, the commonly used linear contrast agents based on the rare-earth element gadolinium have been considered safe and well-tolerated. Recently, concerns regarding this type of contrast agent have been reported, which is why there is an urgent need to develop the next generation of stable contrast agents with enhanced spin-lattice relaxation, as measured by improved T-1 relaxivity at lower doses. Here, we show that by the integration of gadolinium ions in cerium oxide nanoparticles, a stable crystalline 5 nm sized nanoparticulate system with a homogeneous gadolinium ion distribution is obtained. These cerium oxide nanoparticles with entrapped gadolinium deliver strong T-1 relaxivity per gadolinium ion (T-1 relaxivity, r(1) = 12.0 mM(-1) s(-1)) with the potential to act as scavengers of reactive oxygen species (ROS). The presence of Ce3+ sites and oxygen vacancies at the surface plays a critical role in providing the antioxidant properties. The characterization of radial distribution of Ce3+ and Ce4+ oxidation states indicated a higher concentration of Ce3+ at the nanoparticle surfaces. Additionally, we investigated the ROS-scavenging capabilities of pure gadolinium-containing cerium oxide nanoparticles by bioluminescent imaging in vivo, where inhibitory effects on ROS activity are shown.

The innovative construction of bifunctional non-noble electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is imperative for electrochemical water splitting. Herein, we provide a collaborative self-templating method to prepare a hybrid catalyst of nanoporous CoP nanowire (NWs) arrays decorated with carbon-coated CoP nanoparticles (NPs). Its found that the unique structure and morphology of the resultant catalyst can provide abundant available active sites and faciliatate the rapid H-2/O-2 transmission. Additionally, the N-doped carbon improves the conductivity of the catalyst and prevents the aggregation and deactivation of CoP nanoparticles. Forthermore, the strong coupling and synergistic effects by interface engineering are also conducive to the electrochemical performance. Benefiting from these advantages, the CoP NWs/CoP NPs@NC/CC only needs a low overpotential of 103 mV to achieve 10 mA cm(-2) with a small Tafel slope of 87 mV dec(-1) for HER. When employed in an electrolytic cell as an electrocatalyst for overall water splitting, a low voltage of 1.60 V is required to drive 10 mA cm(-2). This study may provide a novel way to fabricate transitionmetal-based catalysts for water splitting.

Transition metal phosphides have been demonstrated to be promising non -noble catalysts for water splitting, yet their electrocatalytic performance is impeded by unfavorable free energies of adsorbed intermediates. The achievement of nanoscale modulation in morphology and electronic states is imperative for enhancing their intrinsic electrocatalytic activity. Herein, we propose a strategy to expedite the water splitting process over NiCoP/FeNiCoP hollow ellipsoids by modulating the electronic structure and d -band center. These unique phosphorus (P) vacancies -rich ellipsoids are synthesized through an ion -exchange reaction between uniform NiCo-nanoprisms and K 3 [Fe(CN) 6 ], followed by NaH 2 PO 2 -assisted phosphorization under N 2 atmosphere. Various characterizations reveals that the titled catalyst possesses high specific surface area, abundant porosity, and accessible inner surfaces, all of which are beneficial for efficient mass transfer and gas diffusion. Moreover, density functional theory (DFT) calculations further confirms that the NiCoP/FeNiCoP heterojunction associated with P vacancies regulate the electronic structures of d -electrons and p -electrons of Co and P atoms, respectively, resulting in a higher desorption efficiency of adsorbed H* intermediates with a lower energy barrier for water splitting. Due to the aforementioned advantages, the resultant NiCoP/FeNiCoP hollow ellipsoids exhibit remarkably low overpotentials of 45 and 266 mV for hydrogen and oxygen evolution reaction to achieve the current densities of 10 and 50 mA cm -2 , respectively. This work not only reports the synthesis of a hollow double -shell structure of NiCoP/FeNiCoP but also introduces a novel strategy for constructing a multifunctional electrocatalyst for water splitting.

Intracellular viscosity plays an important role in regulating cellular morphology and physiology and is closely related to a host of diseases. Especially, the changes in mitochondrial viscosity will cause some common diseases such as hyperlipidemia, Alzheimer's disease and cancer. In this work, we report the design of a red-emissive molecular rotor for the detection of mitochondrial viscosity in live cells. The probe showed fascinating performance, such as specific targeting to mitochondria, high sensitivity to viscosity, and rapid fluorescence response, especially the dual response mode of fluorescence intensity and fluorescence lifetime. By using this probe, we realized monitoring of the mitochondrial viscosity variations in live cells under different physiological processes. Our study offers an opportunity to discover potential tools for mitochondria-related physiology and pathology investigation. A D-pi-A typed fluorescence lifetime probe for sensitively detecting viscosity has been designed and synthesized. BSOH has been successfully applied to real-time monitoring mitochondrial viscosity in live cells by fluorescence lifetime imaging.

A new colorimetric and fluorogenic probe (RN3) based on rhodamine-B has been successfully designed and synthesized. It displays a selective response to Hg2+ in the aqueous buffer solution over the other competing metals. Upon addition of Hg2+, the solution of RN3 exhibits a naked eye observable color change from colorless to red and an intensive fluorescence with about 105-fold enhancement. The changes in the color and fluorescence are ascribed to the ring-opening of spirolactam in rhodamine fluorophore, which is induced by a binding of the constructed receptor to Hg2+ with the association and dissociation constants of 0.22 x 10(5) M-1 and 25.2 mM, respectively. The Jobs plot experiment determines a 1: 1 binding stoichiometry between RN3 and Hg2+. The resultant "turn-on" fluorescence in buffer solution, allows the application of a method to determine Hg2+ levels in the range of 4.0-15.0 mu M, with the limit of detection (LOD) calculated at 60.7 nM (3 sigma/slope). In addition, the fluorescence turn-off and color fading-out happen to the mixture of RN3-Hg2+ by further addition of I- or S2-. The reversible switching cycles of fluorescence intensity upon alternate additions of Hg2+ and S2- demonstrate that RN3 can perform as an INHIBIT logic gate. Furthermore, the potential of RN3 as a fluorescent probe has been demonstrated for cellular imaging. (C) 2016 Elsevier B.V. All rights reserved.

A new visible light excitable fluorescent probe (1) is synthesized by appending a hydroxymethyl-pyridine to rhodamine B hydrazide. The probe displays very specific Hg2+-induced colour change and fluorescent enhancement in the aqueous systems. The "turn-on" response of fluorescence is based on a binding-induced ring-opening process from the spirolactam (nonfluorescent) to acyclic xanthene (fluorescent) in rhodamine B. The coordinating atoms O-center dot-N-N-O-center dot from the hydroxymethyl-pyridine and rhodamine B hydrazide play dominant role in the formation of a complex with 1:1 stoichiometry of Hg2+ to 1. It exhibits a linear response in the range of 0.1-5 mu M with the limit of detection (LOD) of 15.7 nM (3 sigma/slope), while the calculated value of the association constant of Hg2+/1 is 0.70 x 10(5) M-1. Furthermore, confocal microscopy imaging experiment demonstrates the probe 1 can be applied as a fluorescent probe for visualization of Hg2+ in living HeLa cells.

We design and synthesize a new ratiometric fluorescent chemodosimeter (S1) for the selective and sensitive detection of Hg2+. Upon addition of Hg2+, the emission of the S1 exhibits a large bathochromic shift from 393 to 515 nm (up to 122 nm) which is ascribed to an intramolecular charge transfer process in the resultant. The Hg2+-induced dethioacetalization for sensing mechanism has been demonstrated by using high-performance liquid chromatography analysis of the sensing process. The interference experiments further demonstrate that S1 exhibits very high selectivity towards Hg2+ over other coexisting cations/anions. Subsequently, a good linearity of the concentrations of Hg2+ (0-15 mu M) vs the ratiometric signals (I-515/I-393) allows a fluorogenic method for the quantitative detection of Hg2+, with the limitation of detection determined to be 5.22 x 10(-7) M. (C) 2016 Elsevier B.V. All rights reserved.

By ingeniously using a (imino)coumarin-precursor, three reactive fluorogenic probes of MP, FP, and FMP have been fabricated in a single facile synthetic route. MP and FP are able to respectively act as selective "turn-on" fluorescent probes for detecting Hg2+ and F- in buffer solution via specific analyte-induced reactions. Linear ranges for the detection of Hg2+ and F- are 0-10 mu M and 0-100 mu M with the limits of detection (LODs) of 4.0 x 10(-8) M and 1.14 x 10(-6) M (3 delta/slope), respectively. FMP is able to work as a molecular "AND" logic gate-based fluorogenic probe for monitoring the coexistence of Hg2+ and F- via a multistep reaction cascade. The analytes-induced sensing mechanisms have been determined by using high-performance liquid chromatography analysis (HPLC). In addition, three probes show negligible toxicity under the experimental conditions, and are successfully used for monitoring Hg2+ and F- in living cells with good cell permeability. The success of the work demonstrates that ingenious utility of specific analyte-induced reactions and conventional concepts on the appropriate molecular scaffold can definitely deliver tailor-made probes for various intended sensing purposes. (C) 2018 Published by Elsevier B.V.

In this work, we report a novel protein-based nanoprobe (PNP) that can be employed for quantitative analysis of Cu2+ in pure water medium and real samples. Structurally, the proposed nanoprobe comprises a biofriendly protein (hen egg-white lysozyme (HEWL)) and a Cu2+-specific chromogenic agent, where HEWL acts as a nanocarrier encapsulating a structurally tailored rhodamine B derivate. The resulting PNP exhibits a hydrodynamic diameter of similar to 106 nm and efficiently disperses in water, enabling the detection of Cu2+ in pure aqueous systems without the aid of any organic co-solvents. The high sensitivity and selectivity of PNP allow the colorimetric detection of Cu2+ in the presence of other metal interferents with a low detection limit of 160 nM. The satisfying recovery of trace level Cu2+ in environmental samples demonstrate the great potential of employing PNP for the determination of Cu2+ in actual applications. Most importantly, the simple co-grinding method employing proteins and chromogenic agents provides a novel strategy to generate sensing systems that are useful detection of pollutants in aqueous samples. (C) 2021 Elsevier B.V. All rights reserved.

A rhodamine B-based sensor (RS) was designed and synthesized by a combination of the spirolacton rhodamine B (fluorophore) and multidentate chelates (ionophore) with high affinity towards Hg2+. In the presence of Hg2+, the resulting red-orange fluorescence (under UV light) and naked eye red color of IDS are supposed to be used for quantitative and qualitative measurement of Hg2+. Further fluorescent titration and analysis demonstrate that RS can selectively detect Hg2+ within 1 s with a low limit of detection (LOD) of 16 nM in acetonitrile media, meanwhile, the association constant (K-a) was calculated to be 0.32 x 10(5) M-1. More importantly, the resultant complex (RSHg) of RS and Hg2+ has also been successfully applied to detect limited water content in acetonitrile solution. (C) 2020 Published by Elsevier B.V.

Hypochlorous acid (HClO) is one of the most important ROS (reactive oxygen species) and common pollutant in tap-water. However, the determination of HClO with fast response and high sensitivity/selectivity is still an urgent demanding. Here we fabricated a ratiometric fluorescent probe RC based on TBET (through-bond energy transfer) on the platform of coumarin and rhodamine with the thiosemicarbazide group as the linker. This probe could display the characteristic fluorescence emission of coumarin. Upon addition of HClO, the linker was reacted into an oxadiazole, resulting in the opening of spiro-ring of rhodamine. The resultant then gives ratiometric fluorogenic changes. The probe exhibits fast response and high selectivity and sensitivity towards HClO with a low limit of detection (similar to 140 nM). Eventually, RC is successfully applicated for determining spiked HClO in water samples and imaging endogenous HClO in living cells. (C) 2019 Published by Elsevier B.V.

Water-dispersible and luminescent gadolinium oxide (GO) nanoparticles (NPs) were designed and synthesized for potential dual-modal biological imaging. They were obtained by capping gadolinium oxide nanoparticles with a fluorescent glycol-based conjugated carboxylate (HL). The obtained nanoparticles (GO-L) show long-term colloidal stability and intense blue fluorescence. In addition, L can sensitize the luminescence of europium(III) through the so-called antenna effect. Thus, to extend the spectral ranges of emission, europium was introduced into L-modified gadolinium oxide nanoparticles. The obtained Eu-III-doped particles (Eu:GO-L) can provide visible red emission, which is more intensive than that without L capping. The average diameter of the monodisperse modified oxide cores is about 4nm. The average hydrodynamic diameter of the L-modified nanoparticles was estimated to be about 13nm. The nanoparticles show effective longitudinal water proton relaxivity. The relaxivity values obtained for GO-L and Eu:GO-L were r(1)=6.4 and 6.3s(-1)mM(-1) with r(2)/r(1) ratios close to unity at 1.4T. Longitudinal proton relaxivities of these nanoparticles are higher than those of positive contrast agents based on gadolinium complexes such as Gd-DOTA, which are commonly used for clinical magnetic resonance imaging. Moreover, these particles are suitable for cellular imaging and show good biocompatibility.

Introduction

Ethylenediamine-grafted multiwalled carbon nanotubes (MWCNTs-EDA-I and MWCNTs-EDA-II) are optimized and employed to investigate the preconcentration of lead ions (Pb(II)) in trace level.

Results

The results show that Pb(II) can be adsorbed quantitatively on the optimized MWCNTs in the range of pH 4–7 and MWCNTs-EDA-I has a higher maximum Pb(II) adsorption capacity (157.19 mg/g) than MWCNTs-EDA-II (89.16 mg/g). The adsorbed Pb(II) can be eluted completely using 5 mL of 1 mol/L HNO₃.

Discussion

A new approach using a microcolumn packed with the obtained MWCNTs-EDA-I has been developed for the preconcentration of trace amount of Pb(II). Parameters influencing the preconcentration of Pb(II), such as pH of the sample, sample volume, elution solution, and interfering ions, have been examined and optimized in detail. Under optimum experimental conditions, the limit of detection is 0.30 ng/mL with the enrichment factor of 60. The relative standard deviation (R.S.D) was 2.6% at the 20 ng/mL Pb(II) level.

Conclusion

The method has been applied for the preconcentration of trace amount of Pb(II) in environmental water samples with satisfying results.

A facile one-step Cu(I)-catalyzed "click" reaction, between a dansyl-azide and a propargyl-substituted rhodamine B hydrazide, is employed to fabricate a novel FRET ratiometric "off-on" fluorescent probe. The sensitive emission of the donor, a dansyl group, overlaps perfectly with the absorption of the acceptor, xanthene in the open-ring rhodamine. The proposed probe shows high selectivity towards Cu2+. The ratio of emission intensities at 568 and 540 nm (I-568/I-540) exhibits a drastic 28-fold enhancement upon addition of Cu2+. The probe shows an excellent linear relationship between emission ratios and the concentrations of Cu2+ from 10 to 50 mu M, with a detection limit (S/N = 3) of 0.12 mu M. The preliminary cellular studies demonstrated that the probe is cell membrane permeable and could be applied for ratiometric fluorescence imaging of intracellular Cu2+ with almost no cytotoxicity. The ingenuity of the probe design is to construct a FRET donor-acceptor interconnector and a selective receptor simultaneously by "click" reaction. The strategy was verified to have great potential for developing novel FRET probes for Cu2+.

We strategize to utilize the precursors of (imino) coumarin fluorophores to deliver novel reactive Cu+ probes, where tris[(2-pyridyl)-methyl] amine (TPA) works as a reactive receptor towards Cu+. To verify this strategy, CP1, a representative probe and relevant sensing behaviors towards Cu+ are presented here. CP1 features good solubility and fast response for monitoring labile copper in aqueous solution and live cells. The sensing mechanism of CP1 is determined by HPLC titration and mass spectrometric analysis. The probe CP1 exhibits a 60-fold fluorescence enhancement and a detection limitation of 10.8 nM upon the detection of Cu+. CP1 is further applied for imaging labile copper in live cells. This work provides a starting point for future development of Cu+ probes, based on in situ formation of (imino) coumarin scaffolds, as well as their further investigations of copper signaling and biological events. (C) 2016 Elsevier B.V. All rights reserved.

Reactive oxygen species (ROS) regulating the release of free zinc ions (Zn2+) in cellular lysosome is closely related to various pathways of cellular signal transduction, such as inflammation and oxidative stress. Directly visualizing Zn2+ release in lysosome is essential for in-depth understanding these physiological processes, and is still an atelic challenge. In this work, we successfully fabricate a lysosome-specific Zn2+ fluorescent probe and achieve the visualization of ROS-induced Zn2+ release in lysosome of inflammatory cells. The as-prepared probe combines a green fluorophore, an ionophore with five-dentate sites, and a morpholine as the lysosome-specific localization moiety. The fluorescence of the fluorophore in the free probe is suppressed by a photoinduced electron transfer (PET) process from nitrogen atoms in the ionophore. Upon the addition of Zn2+, the fluorescence can be promoted immediately, achieving the real-time detection. Meanwhile, the probe is sensitive and selective to Zn2+, which provides the capability to detect low-concentration of free Zn2+ in lysosomes. Accordingly, the Zn2+ release was clearly observed in lysosome with the increase of ROS levels when the inflammation occurred in living cells. (c) 2018 Published by Elsevier B.V.

Heterostructures formed by the growth of one kind of nanomaterial in/on another have attracted increasing attention due to their microstructural characteristics and potential applications. In this work, SnS2-SnO2 heterostructures were successfully prepared by a facile hydrothermal method. Due to the enhanced visible-light absorption and efficient separation of photogenerated holes and electrons, the SnS2-SnO2 heterostructures display excellent photocatalytic performance for the degradation of rhodamine (RhB) under visible-light irradiation. Additionally, it is found that the introduction of graphene into the heterostructures further improved photocatalytic activity and stability. In particular, the optimized SnS2-SnO2/graphene photocatalyst can degrade 97.1% of RhB within 60 min, which is about 1.38 times greater than that of SnS2-SnO2 heterostructures. This enhanced photocatalytic activity could be attributed to the high surface area and the excellent electron accepting and transporting properties of graphene, which served as an acceptor of the generated electrons to suppress charge recombination. These results provide a new insight for the design and development of hybrid photocatalysts.

The synthesis of NH3 via electrochemical N2 fixation at ambient conditions has been proposed as a promising alternative to the traditional Haber-Bosch process. However, the development of highly efficient and selective electrocatalysts remains a challenge. In this study, uniform Ag@AgP2 @Ni-CoP@C core-shell nanowires were synthesized using a template-engaged strategy. The merging of conductive Ag core with active AgP2 and porous carbon-coated Ni-doped CoP shells favors the mass and electron transfers, effectively lowering the activation energy toward the reduction of N2 to NH3. Density functional theory (DFT) calculations further indicates that the sandwiched AgP2 layer plays crucial roles in promoting electrocatalytic kinetics and suppressing the competitive hydrogen evolution reactions. Benefiting from these advantages, the titled catalyst achieved a high NH3 yield of 16.84 & mu;g h-1 mg-1 cat. at-0.4 V (vs. reversible hydrogen electrode, RHE) and a high Faradaic efficiency of 21.7 % at-0.3 V vs. RHE, as well as high electrochemical and structure stability.

The electrochemical reduction of nitrogen, as a sustainable alternative to the known Haber-Bosch process, possesses promising application prospects in the development of renewable energy storage systems. However, the yield of NH3 and Faraday efficiency are usually very low owing to the loss of active electrocatalysts and competitive hydrogen evolution reactions. Herein, uniform NiS@MoS2 core-shell microspheres are controllably prepared as a potential catalyst for an ambient electrocatalytic N-2 reduction reaction. The NiS@MoS2 microspheres possess highly active intrinsic, sufficient accessible active sites, high structural porosity, and convenient transport channels, consequently boosting the transmission of electrons and mass. Additionally, the interfacial interaction between NiS and MoS2 facilitates electron transfer, which further improves the catalytic activity by optimizing the free energies of reaction intermediates. As a result, the titled NiS@MoS2 shows excellent electrochemical activity and selectivity, capable of achieving a relatively high NH3 yield of 9.66 mu g h(-1) mg(cat)(-1) at -0.3 V (vs. the reversible hydrogen electrode, RHE) and a high FE of 14.8% at -0.1 V vs. RHE in 0.1 M Na2SO4. The work demonstrated here may open a new avenue for the rational design and synthesis of catalysts for the electrochemical synthesis of ammonia.

The development of high-efficiency, robust, and available electrode materials for oxygen evolution reaction (OER) and lithium-ion batteries (LIBs) is critical for clean and sustainable energy system but remains challenging. Herein, a unique yolk-shell structure of Fe2O3 nanotube@hollow Co9S8 nanocage@C is rationally prepared. In a prearranged sequence, the fabrication of Fe2O3 nanotubes is followed by coating of zeolitic imidazolate framework (ZIF-67) layer, chemical etching of ZIF-67 by thioacetamide, and eventual annealing treatment. Benefiting from the hollow structures of Fe2O3 nanotubes and Co9S8 nanocages, the conductivity of carbon coating and the synergy effects between different components, the titled sample possesses abundant accessible active sites, favorable electron transfer rate, and exceptional reaction kinetics in the electrocatalysis. As a result, excellent electrocatalytic activity for alkaline OER is achieved, which delivers a low overpotential of 205 mV at the current density of 10 mA cm(-2) along with the Tafel slope of 55 mV dec(-1). Moreover, this material exhibits excellent high-rate capability and excellent cycle life when employed as anode material of LIBs. This work provides a novel approach for the design and the construction of multifunctional electrode materials for energy conversion and storage.

The synergistic achievement of heteroatom doping, defect engineering and appropriate structural design is efficient to adjust and boost the catalytic performance of catalysts yet challenging. Herein, phosphorus (P)-doped NiS2 hierarchical architectures with sulfur vacancies are synthesized via a Prussian-blue-analogue-sacrificed strategy followed by a phosphidation process. By modulation of P doping and sulfur vacancies, the optimal catalyst manifests outstanding electrocatalytic activities, affording low overpotentials of 73 mV at 10 mA cm-2 for hydrogen evolution reaction (HER), and 255 mV at 20 mA cm-2 for oxygen evolution reaction (OER), respectively. Density functional theory calculations certify that the P dopant not only serves as the new active sites, but also activates the electrochemical activity of neighboring Ni and S sites. Moreover, the synergistic effect of P-doping and sulfur vacancies further improve electrochemical activities of HER and OER by optimizing the adsorption free energy of hydrogen (Delta GH*) and oxygen-containing intermediates (OH*, O* and OOH*), respectively. This finding provides a directive strategy to achieve efficient non-noble metal catalysts for energy conversion and storage.

Water splitting using transition metal sulfides as electrocatalysts has gained considerable attention in the field of renewable energy. However, their electrocatalytic activity is often hindered by unfavorable free energies of adsorbed hydrogen and oxygen-containing intermediates. Herein, phosphorus (P)-doped Co3S4/NiS2 hetero-structures embedded in N-doped carbon nanoboxes were rationally synthesized via a pyrolysis-sulfidation-phosphorization strategy. The hollow structure of the carbon matrix and the nanoparticles contained within it not only result in a high specific surface area, but also protects them from corrosion and acts as a conductive pathway for efficient electron transfer. Density functional theory (DFT) calculations indicate that the intro-duction of P dopants improves the conductivity of NiS2 and Co3S4, promotes the charge transfer process, and creates new electrocatalytic sites. Additionally, the NiS2-Co3S4 heterojunctions can enhance the adsorption efficiency of hydrogen intermediates (H*) and lower the energy barrier of water splitting via a synergistic effect with P-doping. These characteristics collectively enable the titled catalyst to exhibit excellent electrocatalytic activity for water splitting in alkaline medium, requiring only small overpotentials of 150 and 257 mV to achieve a current density of 10 mA cm-2 for hydrogen and oxygen evolution reactions, respectively. This work sheds light on the design and optimization of efficient electrocatalysts for water splitting, with potential implications for renewable energy production.

Oxygen evolution reaction (OER) and urea oxidation reaction (UOR) play important roles in the fields of hydrogen energy production and pollution treatment. Herein, a facile one-step chemical etching strategy is provided for fabricating one-dimensional hierarchical nanorods array composed of CoFe layered double hydroxide (LDH)/metal-organic frameworks (MOFs) supported on carbon cloth as efficient and stable OER and UOR catalysts. By precisely controlling the etching rate, the ligands from Co-MOFs are partially removed, the corresponding metal centers then coordinate with hydroxyl ions to generate ultrathin amorphous CoFe LDH nanosheets. The resultant CoFe LDH/MOFs catalyst possesses large active surface area, enhanced conductivity and extended electron/mass transfer channels, which are beneficial for catalytic reactions. Additionally, the intimate contact between CoFe LDH and MOFs modulates the local electronic structure of the catalytic active site, leading to enhanced adsorption of oxygen-containing intermediates to facilitate fast electrocatalytic reaction. As a result, the optimized CoFe LDH/MOF-0.06 exhibits superior OER activity with a low overpotential of 276 at a current density of 10 mA cm(-2) with long-term durability. Additionally, it merely requires a voltage of 1.45 V to obtain 10 mA cm(-2) in 1 M KOH solution with 0.33 urea and is 56 mV lower than the one in pure KOH. The work presented here may hew out a brand-new route to construct multi-functional electrocatalysts for water splitting, CO2 reduction, nitrogen reduction reactions and so on.

Mixed transition metal oxides (MTMOs) are deemed as promising anode materials for lithium-ion batteries (LIBs) because of the high theoretical capacity and low cost. However, the low electrical conductivity, agglomeration effects, and huge volume variation during discharging/charging still seriously restrict the actual applications of MTMOs as anode materials. Herein, a novel core-shell structure of CoSnO3@carbon-caged NiCo2O4 nanobox (CNC) is rationally designed. It starts from the preparation of CoSnO3@ZIF-67 core-shell nanocubes, followed by chemical etching/anion exchange, dopamine coating and carbonization at high temperature in sequence. It is shown that the CNC achieves high activities from the applied MTMOs components, excellent relief of volume variation from the unique double hollow structure, improved conductivity and inhabited aggregations from the uniform-coated outmost carbon shell, and effective ion/electron transfer rates from the synergetic effects. As a result, the CNC exhibits a discharge capacity of 1548 mA h g(-1) at the first cycle and a retention capacity of 992 mA h g(-1) after 100 cycles at 0.1 A g(-1). In addition, it exhibits a high reversible capacity of about 670 mA h g(-1) after 500 cycles at a current density of 1 A g(-1). The improved Li+ storage performances of CNC demonstrates that such rational design of double hollow structure could be a novel strategy to apply MTMOs as anode materials of LIBs.

Electrochemical water splitting using hollow and defect-rich catalysts has emerged as a promising strategy for efficient hydrogen production. However, the rational design and controllable synthesis of such catalysts with intricate morphology and composition present significant challenges. Herein, we propose a template-engaged approach to fabricate a novel ball-in-ball hollow structure of Co-P-O@N-doped carbon with abundant oxygen vacancies. The synthesis process involves the preparation of uniform cobalt-glycerate (Co-gly) polymer microspheres as precursors, followed by surface coating with ZIF-67 layer, adjustable chemical etching by phytic acid, and controllable pyrolysis at high temperature. The resulting ball-in-ball structure offers a large number of accessible active sites and high redox reaction centers, facilitating efficient charge transport, mass transfer, and gas evolution, which are beneficial for the acceleration of electrocatalytic reaction. Additionally, density functional theory (DFT) calculations indicate that the incorporation of oxygen and the presence of Co-P dangling bonds in CoP significantly enhance the adsorption of oxygenated species, leading to improved intrinsic electroactivity at the single-site level. As a sequence, the titled catalyst exhibits remarkable electrocatalytic activity and stability for water splitting in alkaline media. Notably, it only requires a low overpotential of 283 mV to achieve a current density of 10 mA cm-2 for the oxygen evolution reaction. This work may provide some new insights into the design of complex hollow structures of phosphides with abundant defects for energy conversion.

Photo-/electrocatalysis serves as a cornerstone in addressing global energy shortages and environmental pollution, where the development of efficient and stable catalysts is essential yet challenging. Despite extensive efforts, it's still a formidable task to develop catalysts with excellent catalytic behaviours, stability, and low cost. Because of its high precision, favorable controllability and repeatability, radiation technology has emerged as a potent and versatile strategy for the synthesis and modification of nanomaterials. Through meticulous control of irradiation parameters, including energy, fluence and ion species, various inorganic photo-/electrocatalysts can be effectively synthesized with tailored properties. It also enables the efficient adjustment of physicochemical characteristics, such as heteroatom-doping, defect generation, heterostructure construction, micro/nanostructure control, and so on, all of which are beneficial for lowering reaction energy barriers and enhancing energy conversion efficiency. This review comprehensively outlines the principles governing radiation effects on inorganic catalysts, followed by an in-depth discussion of recent advancements in irradiation-enhanced catalysts for various photo-/electrocatalytic applications, such as hydrogen and oxygen evolution reactions, oxygen reduction reactions, and photocatalytic applications. Furthermore, the challenges associated with ionizing and non-ionizing radiation are discussed and potential avenues for future development are outlined. By summarizing and articulating these innovative strategies, we aim to inspire further development of sustainable energy and environmental solutions to drive a greener future.

Developing efficient and robust non-precious-metal-based catalysts to accelerate electrocatalytic reaction kinetics is crucial for electrochemical water-urea splitting. Herein, Fe-doped NiS-NiS2 heterostructured microspheres, an electrocatalyst, are synthesized via etching Prussian blue analogues following a controlled annealing treatment. The resulting microspheres are constructed by mesoporous nanoplates, granting the virtues of large surface areas, high structural void porosity, and accessible inner surface. These advantages not only provide more redox reaction centers but also strengthen structural robustness and effectively facilitate the mass diffusion and charge transport. Density functional theory simulations validate that the Fe-doping improves the conductivity of nickel sulfides, whereas the NiS-NiS2 heterojunctions induce interface charge rearrangement for optimizing the adsorption free energy of intermediates, resulting in a low overpotential and high electrocatalytic activity. Specifically, an ultralow overpotential of 270 mV at 50 mA cm(-2) for the oxygen evolution reaction (OER) is achieved. After adding 0.33 M urea into 1 M KOH, Fe-doped NiS-NiS2 obtains a strikingly reduced urea oxidation reaction potential of 1.36 V to reach 50 mA cm(-2), around 140 mV less than OER. This work provides insights into the synergistic modulation of electrocatalytic activity of non-noble catalysts for applications in energy conversion systems.

Magnetic Fe3O4@ZnO@nitrogen-doped carbon (Fe3O4@ZnO@N-C) composites with multiple core-shell structures have been successfully synthesized by calcination of ZIF-8 coated Fe3O4@ZnO core-shell nanocrystals. The morphologies and microstructural characteristics are investigated by X-ray diffraction, Fourier-transform infrared spectrometer, transmission electron microscopy, X-ray photoelectron spectroscopy, physical adsorption of nitrogen, and UV-vis diffuse reflectance spectroscopy. The photocatalytic performances are tested by degrading methylene blue (MB) in aqueous solutions under the irradiation of imitative sunlight. The photocatalytic trials indicate that the Fe3O4@ZnO@N-C composites exhibit improved degradation efficiency compared to the Fe3O4@ZnO precursor. The photocatalytic efficiencies of the as-prepared Fe3O4@ZnO@N-C composites towards MB are 93% under irradiation of imitative sunlight for 90 min and still maintained to be 87% after 6 recycles, which shows very good stability and recyclability. Nitrogen-doped carbon is believed to extend the absorption spectra to the visible-light region. The photodegradation kinetics via using the as-prepared Fe3O4@ZnO@N-C composite as a novel photocatalyst are systematically investigated. (C) 2019 Elsevier Ltd. All rights reserved.

Despite rapid improvements in efficiency and brightness of perovskite light-emitting diodes (PeLEDs), the poor operational stability remains a critical challenge hindering their practical applications. Here, we demonstrate greatly improved operational stability of high-efficiency PeLEDs, enabled by incorporating dicarboxylic acids into the precursor for perovskite depositions. We reveal that the dicarboxylic acids efficiently eliminate reactive organic ingredients in perovskite emissive layers through an in situ amidation process, which is catalyzed by the alkaline zinc oxide substrate. The formed stable amides prohibit detrimental reactions between the perovskites and the charge injection layer underneath, stabilizing the perovskites and the interfacial contacts and ensuring the excellent operational stability of the resulting PeLEDs. Through rationally optimizing the amidation reaction in the perovskite emissive layers, we achieve efficient PeLEDs with a peak external quantum efficiency of 18.6% and a long half-life time of 682 h at 20 mA cm(-2), presenting an important breakthrough in PeLEDs.

The design and synthesis of complex multi-component heterostructures is an effective strategy to fabricate cost-efficient catalysts for electrochemical water splitting. Herein, one-dimensional porous Fe3S4-Fe7Se8 heterostructured nanowires confined in carbon (Fe3S4-Fe7Se8@C) were synthesized via the selenization of Fe-based organic-inorganic nanowires. Benefiting from the merits of morphology, composition and surface structure characteristics, i.e., the high structural void porosity, the direct electrical pathways of nanowire topology and the conductive carbon layer coating, the titled catalyst not only offered a larger accessible electrocatalytic interface but also facilitated diffusion of the electrolyte and gas. Moreover, the electron redistribution at the Fe3S4-Fe7Se8 heterojunction interfaces reduced the adsorption free-energy barriers on the active sites, endowing the catalysts with faster reaction kinetics and improved electrocatalytic activity. Accordingly, the optimal Fe3S4-Fe7Se8@C produced a low hydrogen evolution reaction overpotential of 124 mV at 10 mA cm (-2) with a Tafel slope of 111.2 mV dec(-1), and an ultralow oxygen evolution reactions overpotential of 219 mV at 20 mA cm (-2 ), respectively. When applied as both anode and cathode for overall water splitting, a low battery voltage of 1.67 V was achieved along with excellent stability for at least 12 h. The work presented here offered a feasible scheme to fabricate non-noble metal-based electrocatalysts for water splitting. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.

Developing low-cost, efficient, and stable non-precious-metal electrocatalysts with controlled crystal structure, morphology and compositions are highly desirable for hydrogen and oxygen evolution reactions. Herein, a series of phosphorus-doped Fe7S8 nanowires integrated within carbon (P-Fe7S8@C) are rationally synthesized via a one-step phosphorization of one-dimensional (1D) Fe-based organic-inorganic nanowires. The as-obtained P-Fe7S8@C catalysts with modified electronic configurations present typical porous structure, providing plentiful active sites for rapid reaction kinetics. Density functional calculations demonstrate that the doping Fe7S8 with P can effectively enhance the electron density of Fe7S8 around the Fermi level and weaken the Fe-H bonding, leading to the decrease of adsorption free energy barrier on active sites. As a result, the optimal catalyst of P-Fe7S8-600@C exhibits a relatively low overpotential of 136 mV for hydrogen evolution reaction (HER) to reach the current density of 10 mA/cm(2), and a significantly low overpotential of 210 mV for oxygen evolution reaction (OER) at 20 mA/cm(2) in alkaline media. The work presented here may pave the way to design and synthesis of other prominent Fe-based catalysts for water splitting via electronic regulation. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Temperature homeostasis is critical for cells to perform their physiological functions. Among the diverse methods for temperature detection, fluorescent temperature probes stand out as a proven and effective tool, especially for monitoring temperature in cells and suborganelles, with a specific emphasis on mitochondria. The utilization of these probes provides a new opportunity to enhance our understanding of the mechanisms and interconnections underlying various physiological activities related to temperature homeostasis. However, the complexity and variability of cells and suborganelles necessitate fluorescent temperature probes with high resolution and sensitivity. To meet the demanding requirements for intracellular/subcellular temperature detection, several strategies have been developed, offering a range of options to address this challenge. This review examines four fundamental temperature-response strategies employed by small molecule and polymer probes, including intramolecular rotation, polarity sensitivity, Forster resonance energy transfer, and structural changes. The primary emphasis was placed on elucidating molecular design and biological applications specific to each type of probe. Furthermore, this review provides an insightful discussion on factors that may affect fluorescent thermometry, providing valuable perspectives for future development in the field. Finally, the review concludes by presenting cutting-edge response strategies and research insights for mitigating biases in temperature sensing. In this review, we primarily summarized four temperature-response strategies. Then, we further analyzed the chemical modifications and biological applications of the probes. Finally, we have provided a prospective on the future development of probes.

Integrating imaging and therapeutic capabilities into a single entity can offer enhanced diagnostic accuracy and treatment efficacy in clinically effective formulations. Due to the diversity of chemical structures and/or limited solubility of inhibitors or fluorophores, it is essential to employ a robust delivery carrier that can facilitate drug absorption and distribution during its circulation in the blood. This study explores the potential of hollow gadolinium oxide (Gd2O3) nanocarriers in imaging and drug delivery applications. The citric acid (CA)-capped hollow gadolinium oxide nanocarriers were synthesized via urea-assisted precipitation and hydrothermal methods using carbon spheres as sacrificial templates. The resulting nanosized hollow spheres displayed a spherical morphology and demonstrated relaxation rates in the longitudinal and transverse directions, as indicated by their r 1 and r(2) values of 1.8 and 5.3 s(-1) mM(-1), respectively. To mimic the physiological conditions, the hollow gadolinium oxide spheres were loaded separately with antibiotic sparfloxacin and the azo dye Congo red at neutral pH (7.4) and body temperature (37 degrees C). The CR-loaded nanospheres exhibited a time-dependent internalization behavior with HeLa cells, suggesting their imaging potential for intracellular drug delivery. Furthermore, the SP-loaded nanospheres demonstrated antimicrobial activity against both Gram-positive and Gram-negative bacteria, demonstrating their therapeutic potential against bacterial infections. To mitigate the risk of leaching of Gd3+ ions and their inherent toxicity, a CA coating was applied to hollow gadolinium oxide surface which resulted in outstanding cell viability of the surface functionalized nanocarriers. In addition, the CA coating offered additional support for the increased encapsulation and continuous release of drug molecules until 1 week (168 h). The characterization data provide evidence for the potential of CA-capped hollow gadolinium oxide spheres as positive MR contrast agents and their applicability as safe and controlled drug carriers.

Enzyme activity in live cells is dynamically regulated by small-molecule transmitters for maintaining normal physiological functions. A few probes have been devised to measure intracellular enzyme activities by fluorescent imaging, but the study of the regulation of enzyme activity via gasotransmitters in situ remains a long-standing challenge. Herein, we report a three-channel imaging correlation by a single dual-reactive fluorescent probe to measure the dependence of phosphatase activity on the H2S level in cells. The two sites of the probe reactive to H2S and phosphatase individually produce blue and green fluorescent responses, respectively, and resonance energy transfer can be triggered by their coexistence. Fluorescent analysis based on the three-channel imaging correlation shows that cells have an ideal level of H2S to promote phosphatase activity up to its maximum. Significantly, a slight deviation from this H2S level leads to a sharp decrease of phosphatase activity. The discovery further strengthens our understanding of the importance of H2S in cellular signaling and in various human diseases.

Activatable fluorescent probes have been successfully used as molecular tools for biomedical research in the last decades. Fluorescent probes allow the detection of molecular events, providing an extraordinary platform for protein and cellular research. Nevertheless, most of the fluorescent probes reported are susceptible to interferences from endogenous fluorescence (background signal) and limited tissue penetration is expected. These drawbacks prevent the use of fluorescent tracers in the clinical setting. To overcome the limitation of fluorescent probes, we and others have developed activatable magnetic resonance probes. Herein, we report for the first time, an oligonucleotide-based probe with the capability to detect bacteria using magnetic resonance imaging (MRI). The activatable MRI probe consists of a specific oligonucleotide that targets micrococcal nuclease (MN), a nuclease derived from Staphylococcus aureus. The oligonucleotide is flanked by a superparamagnetic iron oxide nanoparticle (SPION) at one end, and by a dendron functionalized with several gadolinium complexes as enhancers, at the other end. Therefore, only upon recognition of the MRI probe by the specific bacteria is the probe activated and the MRI signal can be detected. This approach may be widely applied to detect bacterial infections or other human conditions with the potential to be translated into the clinic as an activatable contrast agent.

Ruddlesden-Popper perovskites (RPPs), consisting of alternating organic spacer layers and inorganic layers, have emerged as a promising alternative to 3D perovskites for both photovoltaic and light-emitting applications. The organic spacer layers provide a wide range of new possibilities to tune the properties and even provide new functionalities for RPPs. However, the preparation of state-of-the-art RPPs requires organic ammonium halides as the starting materials, which need to be ex situ synthesized. A novel approach to prepare high-quality RPP films through in situ formation of organic spacer cations from amines is presented. Compared with control devices fabricated from organic ammonium halides, this new approach results in similar (and even better) device performance for both solar cells and light-emitting diodes. High-quality RPP films are fabricated based on different types of amines, demonstrating the universality of the approach. This approach not only represents a new pathway to fabricate efficient devices based on RPPs, but also provides an effective method to screen new organic spacers with further improved performance.

Chrome-based anodization and sealing combined is a cost-effective solution for developing good corrosion protective coatings on aluminum (Al) and its alloys. The toxicity of hexavalent chromium, however, requires new, sustainable, environmentally friendly, and efficient chromate-free sealing procedures. Herein, a combination of cerium (Ce) sealing and hydrothermal sealing (HTS) is employed to improve the corrosion resistance of the commonly used alloy AA2024-T3 anodized by tartaric sulfuric acid (TSA). The morphologies and components of the resulting surfaces are systematically studied. Characterization technologies such as SEM, TEM, EDX, XRD, and XPS demonstrate the in-situ growth of Ce oxide nanoparticles all through the porous structures of the anodic coating and closing of the pores by additional HTS treatment. The results from the standardized corrosion test (ASTM B895) demonstrate an improved corrosion resistance obtained by the utilized chrome-free process.

Investigating lipid droplets (LDs) behaviours is essential to deeply understand the physiology of LDs, such as their growths, movements, fusion/division, and autophagy. Among these behaviours, the growth of LDs is one of the most difficult to track due to the very subtle morphology evolution in a short time window. The major obstacle is that conventional LDs-specific dyes with low photostability cannot indicate the LDs size change. To address this issue, we synthesize a hydrophobic and photostable fluorescent dye (TPA-AD) and load it into the neutral lipid micelles (as artificial adiposomes). The highly hydrophobic TPA-AD enables the specific accumulation into intracellular LDs and the ready loading artificial adiposomes. When the intracellular LDs take TPA-AD-labeled adiposomes, by fusion, the sizes of LDs gradually grow, and LDs are simultaneously lighted up by the fluorescence of TPA-AD. Importantly, the high photostability of TPA-AD ensures the enhanced fluorescence signals. The finding here will further strengthen the understanding of LDs dynamics and fat metabolism.

Using metal organic precursors in materials synthesis remains a challenge due to their high moisture susceptibility. In this work, we describe a facile methodology for the synthesis of Gd2O3-based contrast agents from two new gadolinium-based complexes. [Gd(PyTFP)(4)] (PyH) 1 (PyTFP = C8H5NOF3, Py = C5H5N) and [Gd(DMOTFP)(3)Py] 2 (DMOTFP = C8H7NO2F3) were synthesized via a classical ligand exchange reaction of [Gd{N(SiMe3)(2)}(3)] under inert conditions. As a result, X-ray diffraction analysis revealed a distorted square antiprismatic coordination and an augmented triangular prismatic arrangement of ligands around gadolinium atoms in 1 and 2, respectively. It also showed that 1 is an anionic complex of formula [Gd(PyTFP)(4)](PyH), while a neutral tris-compound, [Gd(DMOTFP)(3)Py], was obtained as a pyridine adduct in 2. Fast and reproducible microwave-assisted decomposition of 1 and 2 provided homogeneous Gd(OH)(3) nanorods at mild temperature without using any surfactant or capping reagent. As-synthesized nanorods were easily transformed into a cubic phase of Gd2O3 nanoparticles by thermal treatment under ambient conditions. The magnetic measurement showed the typical paramagnetic behavior of the Gd2O3 nanoparticles (NPs). The cytotoxicity profile demonstrates the biocompatibility and negligible toxicity of the as-synthesized nanoprobes. The suggested approach provides a new class of gadolinium-based precursors which allows facile synthesis of highly crystalline Gd2O3 NPs.

Fluorescence-assisted tools based on organic molecules have been extensively applied to interrogate complex biological processes in a non-invasive manner with good sensitivity, high resolution, and rich contrast. However, the signal-to-noise ratio is an essential factor to be reckoned with during collecting images for high fidelity. In view of this, the wash-free strategy is proven as a promising and important approach to improve the signal-to-noise ratio, thus a thorough introduction is presented in the current review about wash-free fluorescent tools based on organic molecules. Firstly, generalization and summarization of the principles for designing wash-free molecular fluorescent tools (WFTs) are made. Subsequently, to make the thought of molecule design more legible, a wash-free strategy is highlighted in recent studies from four diverse but tightly binding aspects: (1) special chemical structures, (2) molecular interactions, (3) bio-orthogonal reactions, (4) abiotic reactions. Meanwhile, biomedical applications including bioimaging, biodetection, and therapy, are ready to be accompanied by. Finally, the prospects for WFTs are elaborated and discussed. This review is a timely conclusion about wash-free strategy in the fluorescence-guided biomedical applications, which may bring WFTs to the forefront and accelerate their extensive applications in biology and medicine. In this review, the design principles for wash-free molecular fluorescent tools are highlighted in four diverse details. Meanwhile, biomedical applications including wash-free fluorescent imaging of organelles, cellular microenvironment, biomacromolecules, and small species, as well as therapy and potential drug delivery, are also emphasized. This review may bring wash-free molecular fluorescent tools to the forefront, as well as expand the applications in biology and medicine. image