Highly photoluminescent MoOx quantum dots: Facile synthesis and application in off-on Pi sensing in lake water samples

Molybdenum oxide (MoO_x) is a well-studied transition-metal semiconductor material, and has a wider band gap than MoS₂ which makes it become a promising versatile probe in a variety of fields, such as gas sensor, catalysis, energy storage ect. However, few MoO_x nanomaterials possessing photoluminescence have been reported until now, not to mention the application as photoluminescent probes. Herein, a one-pot method is developed for facile synthesis of highly photoluminescent MoO_x quantum dots (MoO_x QDs) in which commercial molybdenum disulfide powder and hydrogen peroxide (H₂O₂) are involved as the precursor and oxidant, respectively. Compared with current synthesis methods, the proposed one has the advantages of rapid, one-pot, easily prepared, environment friendly as well as strong photoluminescence. The obtained MoO_x QDs is further utilized as an efficient photoluminescent probe, and a new off-on sensor has been constructed for phosphate (Pi) determination in complicated lake water samples, attributed to the fact that the binding affinity of Eu³⁺ ions to the oxygen atoms from Pi is much higher than that from the surface of MoO_x QDs. Under the optimal conditions, a good linear relationship was found between the enhanced photoluminescence intensity and Pi concentration in the range of 0.1–160.0 μM with the detection limit of 56 nM (3σ/k). The first application of the photoluminescent MoO_x nanomaterials for ion photochemical sensing will open the gate of employing MoO_x nanomaterials as versatile probes in a variety of fields, such as chemi-/bio-sensor, cell imaging, biomedical and so on.     

A Polypyridyl‐Based Layered Complex as Dual‐Functional Co‐catalyst for Photo‐Driven Organic Dyes Degradation and Water Splitting

With the ever‐increasing concerns on environmental pollution and energy crisis, it is of great urgency to develop high‐performance photocatalyst to eliminate organic pollutants from wastewater and produce hydrogen via water splitting. Herein, a polypyridyl‐based mixed covalent Cu^I/II complex with triangular {Cu₃} and rhombic {Cu₂Cl₄} subunits alternately extended by mixed SCN^– and Cl^– heterobridges [Cu₄(DNP)(SCN)Cl₄]_n ( 1 ) [DNP = 2,6‐bis(1,8‐naphthyridine‐2‐yl)pyridine] was solvothermally synthesized and employed as a dual‐functional co‐photocatalyst. Resulting from a narrowed band‐gap of 1.07 eV with suitable redox potential and unsaturated Cu^I/II sites, the complex together with H₂O₂ can effectively degrade Rhodamine B and methyl orange up to 87.4 and 88.2 %, respectively. Meanwhile, the complex mixed with H₂PtCl₆ can also accelerate the photocatalytic water splitting in the absence of a photosensitizer with the hydrogen production rate of 27.5 μmol · g^–1 · h^–1. These interesting findings may provide informative hints for the design of the multiple responsive photocatalysts.     

Non‐3d Metal Modulation of a Cobalt Imidazolate Framework for Excellent Electrocatalytic Oxygen Evolution in Neutral Media

Cobalt imidazolate frameworks are classical electrocatalysts for the oxygen evolution reaction (OER) but suffer from the relatively low activity. Here, a non‐3d metal modulation strategy is presented for enhancing the OER activity of cobalt imidazolate frameworks. Two isomorphous frameworks [Co₄(MO₄)(eim)₆] (M=Mo or W, Heim=2‐ethylimidazole) having Co(eim)₃(MO₄) units and high water stabilities were designed and synthesized. In different neutral media, the Mo‐modulated framework coated on a glassy carbon electrode shows the best OER performances (1 mA cm^?2 at an overpotential of 210 mV in CO₂‐saturated 0.5 m KHCO₃ electrolyte and 2/10/22 mA cm^?2 at overpotential of 388/490/570 mV in phosphate buffer solution) among non‐precious metal catalysts and even outperforms RuO₂. Spectroscopic measurements and computational simulations revealed that the non‐3d metals modulate the electronic structure of Co for optimum reactant/product adsorption and tailor the energy of rate‐determining step to a more moderate value.     

Multiple Photoluminescent Processes from Pyrene Derivatives with Aggregation‐ and Mechano‐Induced Excimer Emission

Two novel pyrene‐based isocyanide gold(I) complexes have been designed and synthesized. The different structures lead to distinct and diverse photophysical properties both in solution and in the aggregate state. Multiple photoluminescence, involving monomer emission, locally excited emission and excimer emission, are observed. Notably, an excimer is formed by aggregation in solution and external mechanical stimulation in the solid state, showing aggregation‐ and mechano‐induced excimer emission.     

Aptamer functionalized magnetic graphene oxide nanocomposites for highly selective capture of histones

The binding coverage of aptamer was an important restricted factor for aptamer‐based affinity enrichment strategy for capturing target molecules. Herein, we designed and prepared aptamer functionalized graphene oxide based nanocomposites (GO/NH₂‐NTA/Fe₃O₄/PEI/Au), and the coverage density of aptamer was high to 33.1 nmol/mg. The high aptamer coverage density was contributed to the large surface area of graphene oxide. The successive modification of Nα,Nα‐Bis(carboxymethyl)‐L‐lysine, magnetic nanoparticles, polyethylenimine, and Au nanoparticles ensured the histone purification with fast speed and high purity. Histones could be captured rapidly and specifically from nucleoproteins by our aptamer based purification strategy, while traditional acid‐extraction could not specifically enrich histones. Compared with traditional acid‐extraction method, rapid and efficient discovery of histones and their post‐translational modifications, such as several kinds of methylation at H3.1K9 and H3.1K27, were achieved confidently. It demonstrated that our aptamer functionalized magnetic graphene oxide nanocomposites have a great potential for histone analysis.     

A Smart Photochromic Semiconductor: Breaking the Intrinsic Positive Relation Between Conductance and Temperature

Breaking the intrinsic rule of semiconductors that conductivity increases with increase of temperature and realizing a dramatic dropping of conductivity at high temperature may arouse new intriguing applications, such as circuit overload or over‐temperature protecting. This goal has now been achieved through T‐type electron‐transfer photochromism of one organic semiconductor assembled by intermolecular cation???π interactions. Conductivity of the viologen‐based model semiconductor (H₂bipy)(Hox)₂ (H₂bipy=4,4′‐bipyridin‐1,1′‐dium; ox=oxalate) increased by 2 orders of magnitude after photoinduced electron transfer (a record for photoswitchable organic semiconductors) and generation of radical cation???π interactions, and fell by approximately 81 % at 100 °C through reverse electron transfer and degeneration of the radical cation???π interactions. The model semiconductor has at least two different electron transfer pathways in the decoloration process.     

Two New Indole Alkaloids from Evodia rutaecarpa

The tyuit of Evodia rutaecarpa (Juss.) Benth is a Chinese traditional drug (Wu-Chu-Yu).The components of Wu-Chu-Yu have been studied by several groups, including indolealkaloids,quinolone alkaloids. limonoids and other kinds]. Further chemical investigationofthis drug led us to isolate two new indole alkaloids 1 and 2. This is the first time toisolate indolinone alkaloids from this plant.Wuchuyuamide I (l ), was isolated as colorless needles, m,p. 261 -262<> C (CHCI,MeOH), [Q].=# 0(c 0…     

Analysis of doxorubicin uptake in single human leukemia K562 cells using capillary electrophoresis coupled with laser-induced fluorescence detection

The doxorubicin (DOX) uptake in single human leukemia K562 cells with changes in both drug dosage and exposure period was studied using capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF) detection. The cells were treated with DOX at different concentrations (1, 3, 10, 20, 30, and 50 μM) and for different exposure times (1, 3, 5, 24, and 48 h). At least 20 cells were analyzed for each DOX-treated cell population. A marked heterogeneity in DOX uptake among single cells was observed, because the relative standard deviation of the uptake of DOX by single cells ranged from 24.0% to 61.1% within each cell population. The cell-to-cell heterogeneity in DOX uptake first decreased and then became constant with increasing drug concentration, but it did not exhibit regular variation with increasing exposure time. The mean DOX uptake was a linear function of drug concentration (r ≥ 0.9667). In terms of the correlation with exposure time, the mean DOX uptake reached its maximum at 3 h for the cell populations treated with 1–10 μM DOX, while it kept increasing during 48 h exposure of cell populations to 20–50 μM DOX. Because it eliminates DOX fluorescence quenching and sample loss, the CE-LIF method directly detects the true DOX uptake by single cells, and thus presents accurate information on both the cell-to-cell heterogeneity in DOX uptake and the patterns of DOX uptake in K562 cells as functions of drug concentration and exposure time.     

Micro-solid phase equilibrium extraction with highly ordered TiO2 nanotube arrays: a new approach for the enrichment and measurement of organochlorine pesticides at trace level in environmental water samples

Ordered TiO₂ nanotube arrays have been widely used in many fields such as photocatalysis, self-cleaning, solar cells, gas sensing, and catalysis. This present study exploited a new functional application of the ordered TiO₂ nanotube arrays. A micro-solid phase equilibrium extraction using ordered TiO₂ nanotube arrays was developed for the enrichment and measurement of organochlorine pesticides prior to gas chromatography-electron capture detection. Ordered TiO₂ nanotube arrays exhibited excellent merits on the pre-concentration of organochlorine pesticides and lower detection limits of 0.10, 0.10, 0.10, 0.098, 0.0076, 0.0097, 0.016, and 0.023 μg L⁻¹ for α-HCH, β-HCH, γ-HCH, δ-HCH, p,p’-DDE, p,p’-DDD, o,p’-DDT, and p,p’-DDT, respectively, were achieved. Four real water samples were used for validation, and the spiked recoveries were in the range of 78–102.8%. These results demonstrated that the developed micro-solid phase equilibrium extraction using ordered TiO₂ nanotube arrays would be very constructive and have a great beginning with a brand new prospect in the analysis of environmental pollutants.     

A glassy carbon electrode modified with poly(eriochrome black T) for sensitive determination of adenine and guanine

A thin film of poly(eriochrome black T) was deposited on the surface of glassy carbon electrode by cyclic voltammetry, and this system is shown to enable the sensitive determination of adenine (A) and guanine (G). Scanning electron microscopy, Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy were carried out to characterize the film which exhibits excellent electrocatalytic activity toward the oxidation of A and G in 0.1 M phosphate buffer solution (pH 4.0). Square wave voltammetry reveals an oxidation peak at 1084 mV whose current is linearly related to the concentration of A in the range from 0.05 to 1.00 μM. The oxidation peak for G occurs at 788 mV, and its current is linearly related to the concentration of G in the range from 0.025 to 1.00 μM. The detection limits are 0.017 μM for A and 0.008 μM for G (at S/N?=?3), respectively. The modified electrode displays good reproducibility and selectivity for the determination of A and G. The sensor was applied to quantify A and G in fish sperm DNA with satisfactory results.