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The research on electron transfer coupled spin transition regulating the valence state and spin state transition of metal ions is promising and challenging. Herein, we report a cyano-bridged {Fe III2 Fe II2 } molecular square complex, {[Fe(Tp)(CN)3]2 [Fe(bnbpen)]2}(ClO4)2·8CH3OH (1·8CH3OH, bnbpen = N,N′-bis-(2-naphthylmethyl)-N,N′-bis(2-picolayl)-ethylenediamine), and its free of solvents form (1). Combined single-crystal X-ray diffraction, temperature-dependent infrared (IR) spectra, magnetic measurements, and Mössbauer spectra reveal that 1·8CH3OH and 1 exhibit reversible one-step and two-step electron transfer coupled spin transition (ETCST) with temperature change, between the low-temperature state {FeII,LS(μ-CN)FeIII,LS}2 (LS = low spin, HS = high spin) and the high-temperature state {FeIII,LS(μ-CN)FeII,HS}2, respectively. [ABSTRACT FROM AUTHOR]

The high theoretical capacity and graphene-like structure enable WS2 to be a promising anode material for fast-charging sodium-ion batteries. However, poor intrinsic electrical conductivity and large Na+-diffusion energy barrier limit its practical applications. Here, an atomic-interface strategy and N,O co-doping were first introduced for WS2 electrodes to obtain a unique WS2/C nanocomposite. The atomic-interface strategy that allowed the construction of a unilamellar interoverlapped superstructure maximized the contact area of WS2 and C, thus significantly improving the electrical conductivity and decreasing the Na+-diffusion energy barrier of WS2 electrodes during cycling. More importantly, the atomic-interface strategy suppressed the growth of superparamagnetic W metallic nanoparticles during conversion reactions, resulting in a strong surface-capacitance effect to boost the Na+ transport. Besides, N,O co-doping changed the electronic structure of WS2 to decrease the bandgap from 1.6 to 0 eV and enlarged the interlayer spacing between WS2 and C, thus boosting the electron and ion transport. Consequently, WS2/C exhibited an ultrafast Na+-storage capability (450.8 mA h g−1 at 13 A g−1), with an ultrahigh capacity of 669.2 mA h g−1 at 0.065 A g−1 and an ultralong lifetime of over 3000 cycles at 6.5 A g−1 in half-cells. Further, the full-cells showed superior fast-charging capability with an 80.6% capacity retention at 1.95 A g−1. [ABSTRACT FROM AUTHOR]

A simple colorimetric sensing strategy for Hg2+ ions was developed using silver/copper nanoclusters (Ag/Cu NCs) with excellent selectivity and sensitivity. Bimetallic Ag/Cu NCs were synthesized by using glutathione (GSH) as a template and sodium borohydride as a reducing agent. It was found that the peroxidase-like activity of Ag/Cu NCs was significantly enhanced in the presence of Hg2+. Therefore, a colorimetric method based on catalysis was developed to detect Hg2+ with a linear concentration range of 0.1–700 nM and a detection limit of 0.05 nM (S/N = 3). The common species have no effect on Hg2+ ion detection. Furthermore, this method is applicable to accurately detect Hg2+ in real aqueous samples and is reproducible. Therefore, owing to the merits of sensitivity, selectivity, rapid response and visual read-out, it can be promising in the development of a portable Hg2+ analyzer for on-site detection. [ABSTRACT FROM AUTHOR]

Histidine can trigger bimetallic gold/copper nanoclusters to turn on strong red fluoresence, which is capable of sensing nanomolar levels of histidine selectively. [ABSTRACT FROM AUTHOR]

A highly selective and reproducible electroanalysis strategy was developed for probing histidine using tetrahedral copper metal organic frameworks. It can facilitate His detection through the stable "turn-on" signal output of solid-state CuCl electrochemistry at a potential approaching zero, with the level down to about 25 nM in blood. [ABSTRACT FROM AUTHOR]

Polymer prodrug micelles, combining the advantages of prodrugs and polymer micelles, can greatly improve the solubility, permeability and stability of drugs. In this work, amphiphilic block copolymers poly(α-azide caprolactone-co-caprolactone)-b-poly(2-methacryloyloxyethyl phosphorylcholine), P(ACL-co-CL)-b-PMPC, were synthesized, and an antineoplastic drug 7-ethyl-10-hydroxy camptothecin (SN38) was grafted to the amphiphilic copolymers to obtain a prodrug and their micelles. The preparation of P(ACL-co-CL)-b-PMPC was proceeded by ring-opening polymerization of ε-caprolactone/α-bromide caprolactone, converting the bromide to an azide, and atom transfer radical polymerization (ATRP). The camptothecin derivative SN38-alkyne was bonded to the polymer to obtain P(CL/CL-g-SN38)-b-PMPC by a “click reaction”. The obtained polymer–drug complex can easily self-assemble to form prodrug micelles with the shell composed of PMPC and the core composed of PCL and SN38. The micelles presented characteristics including improved drug loading efficiency and stabilization of the drug. In vivo, the retention time of the prodrug micelles in blood could be tripled, and the clearance was delayed compared with the SN38 solution. The in vivo anti-tumor experiments demonstrated that the prodrug micelles had a better treatment effect and low toxicity to 4T1-bearing BALB/C mice. [ABSTRACT FROM AUTHOR]

A solid-state fluorimetric strategy has been developed using test strips coated with Q-graphene-loaded metal–organic framework nanocomposites featuring water-triggered fluorescence turn-on. It can facilitate the real-time evaluation of trace water in organic solvents, with the level down to about 0.015% in alcohol. [ABSTRACT FROM AUTHOR]

An ultrasensitive and high-throughput visualized colorimetric method has been initially developed with a wettable microwells array for probing guanine base-containing anthrax DNAs in blood based on silver deposition amplified by the synergic TiO2 photocatalysis and guanine photoreduction under visible light. Hydrophilic microwells were first created on the hydrophobic slides to yield the wettable microwells array, on which photocatalytic titanium dioxide (TiO2) nanoparticles were deposited with dopamine (DA) to yield TiO2@DA for anchoring single strand DNA (ssDNA) capture probes without guanine bases. After the hybridization of the targeted anthrax DNAs, exonuclease I (Exo I) was introduced into the microwells to selectively digest the unhybridized ssDNA probes. The silver deposition was further conducted by the synergic photocatalysis of TiO2@DA and photoreduction of guanine bases of anthrax DNAs, thus achieving the amplified silver signals for the visualized colorimetric assays. Moreover, benefitting from the wettability feature of the hydrophilic–hydrophobic interfaces of the microwells array so fabricated, DNA analytes could be accumulated from the sample droplets through the condensing enrichment process to realize the ultrasensitive detection, in addition to circumventing any crossover contaminants between the sample droplets. The developed visualized colorimetric method with the microwells array was subsequently applied for probing anthrax DNAs in blood with levels down to 1.0 fM. DNAs with single-base and double-base mutations could also be identified accurately. Importantly, such a biosensing design route of a wettable microwells array, in combination with the photocatalytic silver deposition and specific Exo I-catalytic probe digestion, may promise extensive applications for the high-throughput, ultrasensitive, and selective detection of guanine-containing DNA targets with ultra-trace levels in complicated samples like blood. [ABSTRACT FROM AUTHOR]

Phosphorylcholine micelles based on pH/reduction responsive copolymers, poly(ε-caprolactone)-ss-b-poly((N,N-diethylaminoethyl methacrylate)-r-poly(2-methacryloyloxyethyl phosphorylcholine)) (PCL-ss-PDEAPMPC) were developed for the intracellular delivery of doxorubicin. The micelles were spherical (less than 90 nm in diameter) and demonstrated pH/reduction sensitivity. The DOX loaded micelles presented the fastest drug release under simultaneously acidic and reductive conditions. Although PCL20-ss-PDEA5PMPC10 had lower pH sensitivity than PCL20-ss-PDEA15PMPC10, the DOX loaded micelles of the former released the drug faster than the latter at pH 5.0 and in the presence of a reductant. The cytotoxicities of the blank micelles and the drug-loaded micelles were investigated using the human cervical cancer cell line (HeLa). The IC50 (half maximal inhibitory concentration) of PCL20-ss-PDEA5PMPC10 micelles was the lowest among PCL-ss-PDEAPMPC micelles. The results of CLSM and flow cytometry showed that the micelles effectively delivered the drug cargo into cancer cells. The cellular uptake pathways of PCL-ss-PDEAPMPC micelles were mainly clathrin-mediated endocytosis, and accompanied by a certain degree of giant pinocytosis. [ABSTRACT FROM AUTHOR]

Alcohol solvents especially isopropanol were demonstrated for the first time to endow silver nanoclusters (AgNCs) in water with dramatically enhanced red fluorescence. More importantly, the specific iodide recognition capability of the AgNCs could thus be obtained towards a highly selective fluorimetric assay for detecting iodide ions in urine. [ABSTRACT FROM AUTHOR]

A porous hydrogel scaffold was fabricated for the first time to encapsulate chromogenic reaction substrates onto arrayed capillary tubes, resulting in a visual and high-throughput colorimetric method for rapid occult blood tests (OBTs) based on the hemoglobin (Hgb)-catalyzed chromogenic reactions. Gelatin (Gel), a biodegradable and biocompatible polymer, was introduced to couple with p-hydroxyphenyl-propionic acid (HPA) yielding the Gel–HPA hydrogel scaffold. Chromogenic reaction substrates of 3,3,5,5-tetramethylbenzidine and H2O2 were then encapsulated into the Gel–HPA matrix and further attached onto the amine-derivatized capillary tubes by forming porous chromogenic composites through the HPA-mediated bridging of Gel by the oxidization of H2O2. The developed Hgb catalysis-based OBT platform can facilitate the detection of Hgb with the level down to 0.125 μg mL−1 in human excreta (i.e., saliva, urine, and feces) through capillarity-enabled automatic sampling. This simple, sensitive, selective, and high-throughput colorimetric method may be promising for the bedside OBT for point-of-care monitoring and rapid diagnostics of clinical bleeding diseases. [ABSTRACT FROM AUTHOR]

The research on electron transfer coupled spin transition regulating the valence state and spin state transition of metal ions is promising and challenging. Herein, we report a cyano-bridged {FeIII2FeII2} molecular square complex, {[Fe(Tp)(CN) 3 ] 2 [Fe(bnbpen)] 2 }(ClO 4 ) 2 ·8CH 3 OH (1·8CH 3 OH, bnbpen = N , N '-bis-(2-naphthylmethyl)- N , N '-bis(2-picolayl)-ethylenediamine), and its free of solvents form (1). Combined single-crystal X-ray diffraction, temperature-dependent infrared (IR) spectra, magnetic measurements, and Mössbauer spectra reveal that 1·8CH 3 OH and 1 exhibit reversible one-step and two-step electron transfer coupled spin transition (ETCST) with temperature change, between the low-temperature state {Fe II,LS (μ-CN)Fe III,LS } 2 (LS = low spin, HS = high spin) and the high-temperature state {Fe III,LS (μ-CN)Fe II,HS } 2 , respectively.

A simple colorimetric sensing strategy for Hg 2+ ions was developed using silver/copper nanoclusters (Ag/Cu NCs) with excellent selectivity and sensitivity. Bimetallic Ag/Cu NCs were synthesized by using glutathione (GSH) as a template and sodium borohydride as a reducing agent. It was found that the peroxidase-like activity of Ag/Cu NCs was significantly enhanced in the presence of Hg 2+ . Therefore, a colorimetric method based on catalysis was developed to detect Hg 2+ with a linear concentration range of 0.1-700 nM and a detection limit of 0.05 nM (S/N = 3). The common species have no effect on Hg 2+ ion detection. Furthermore, this method is applicable to accurately detect Hg 2+ in real aqueous samples and is reproducible. Therefore, owing to the merits of sensitivity, selectivity, rapid response and visual read-out, it can be promising in the development of a portable Hg 2+ analyzer for on-site detection.

Gold nanoplates (AuNPTs) exhibit outstanding photothermal conversion efficiency (68.5%) and peroxidase-like activity. The combination of the very low H2O2 concentration (0.1 mM) and the low AuNPT dosage (50 μg mL-1) with 808 nm laser irradiation (1 W cm-2, 3 min) shows excellent synergistic antibacterial ability and healing of MRSA-infected wounds in vivo.

An ultrasensitive and high-throughput visualized colorimetric method has been initially developed with a wettable microwells array for probing guanine base-containing anthrax DNAs in blood based on silver deposition amplified by the synergic TiO 2 photocatalysis and guanine photoreduction under visible light. Hydrophilic microwells were first created on the hydrophobic slides to yield the wettable microwells array, on which photocatalytic titanium dioxide (TiO 2 ) nanoparticles were deposited with dopamine (DA) to yield TiO 2 @DA for anchoring single strand DNA (ssDNA) capture probes without guanine bases. After the hybridization of the targeted anthrax DNAs, exonuclease I (Exo I) was introduced into the microwells to selectively digest the unhybridized ssDNA probes. The silver deposition was further conducted by the synergic photocatalysis of TiO 2 @DA and photoreduction of guanine bases of anthrax DNAs, thus achieving the amplified silver signals for the visualized colorimetric assays. Moreover, benefitting from the wettability feature of the hydrophilic-hydrophobic interfaces of the microwells array so fabricated, DNA analytes could be accumulated from the sample droplets through the condensing enrichment process to realize the ultrasensitive detection, in addition to circumventing any crossover contaminants between the sample droplets. The developed visualized colorimetric method with the microwells array was subsequently applied for probing anthrax DNAs in blood with levels down to 1.0 fM. DNAs with single-base and double-base mutations could also be identified accurately. Importantly, such a biosensing design route of a wettable microwells array, in combination with the photocatalytic silver deposition and specific Exo I-catalytic probe digestion, may promise extensive applications for the high-throughput, ultrasensitive, and selective detection of guanine-containing DNA targets with ultra-trace levels in complicated samples like blood.