Synthesis of a novel fluorescent probe based on acridine skeleton used for sensitive determination of DNA

In this study, a novel fluorescent probe of acridine derivative N-((N-(2-dimethylamino)ethyl)acridine-4-carboxamide)-alpha-alanine (N-(ACR-4-CA)-alpha-ALA) was synthesized. The structure of the new compound was characterized by (1)H NMR, MS, elemental analysis, fluorescent and ultraviolet spectra. It was found that DNA had the ability to quench the fluorescence of N-(ACR-4-CA)-alpha-ALA, and the quenched intensity of fluorescence was proportional to the concentration of DNA. A method for DNA determination based on the quenching fluorescence (lambda(ex) = 260 nm, lambda(em) = 451 nm) of N-(ACR-4-CA)-alpha-ALA was established. Under optimal conditions, the linear range is 0.05-2.0 microg mL(-1) for both fish semen (fsDNA) and calf thymus DNA (ctDNA). The corresponding determination limits are 9.1 ng mL(-1) for fsDNA and 8.7 ng mL(-1) for ctDNA, respectively. The results suggested that the interaction mode between N-(ACR-4-CA)-alpha-ALA and DNA was intercalative binding. The intrinsic binding constant was determined and the result showed a large binding constant of N-(ACR-4-CA)-alpha-ALA with DNA.     

Determination of trace chlorine dioxide based on the plasmon resonance scattering of silver nanoparticles

A plasmon resonance scattering (PRS) method for chlorine dioxide is reported based on the oxidization of silver nanoparticles (NPs) by it, in pH 9.1 ammonia-ammonium nitrate buffer solutions. Silver NPs exhibit strong PRS signals at 470nm, and can be oxidized by ClO(2), which results in PRS quenching at 470nm. It was found that the PRS quenching intensity is proportional to the concentration of chlorine dioxide over the range of 0.0011-0.185microg/mL, with a detection limit (3sigma) of 0.00050microg/mL and the correlation coefficient of 0.9995. The method is simple, rapid and cost effective. It was applied to the determination of chlorine dioxide in drinking water, with satisfactory results.     

Distinct Hydrogen-bonded M^Ⅱ（H2O）8 Clusters as Second Building Units for 1-D, 2-D and 3-D Supramolecular Architectures （M = Cobalt and Nickel）

Two mononuclear metal-organic complexes, [Co（Hmpdc）2（H2O）4]·4H2O 1 and [Ni（Hfmpdc）2（H2O）4]·6H2O 2, were prepared from 2,6-dimethylpyridine-3,5-dicarboxylic acid （Hzmpdc） and 4-furyl-2,6-dimethylpyridine-3,5-dicarboxylic acid （H2fmpdc） with M（NO3）2 salts, respectively, and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectroscopy, and photoluminescent measurement. Complex 1 crystallizes in triclinic, space group P1 with a = 7.634（5）, b = 8.695（5）, c = 10.757（6）A, α = 69.647（7）, β = 69.957（8）, γ = 83.733（7）°, V = 628.9（7）A^3, Dc = 1. 561 g/cm^3,μ（MoKa） = 0.763 mm^-1, F（000） = 309, Z = 1, the final R = 0.0553 and wR = 0.1469 for 1909 observed reflections （Ⅰ 〉 2σ（Ⅰ））. Complex 2 crystallizes in monoclinic, space group P21/n with a = 9.5934（16）, b = 12.422（2）, c = 14.826（3） A, β = 105.201（2）°, V = 1705.0（5）A3, Dc = 1. 479 g/cm^3,μ（MoKa） = 0.655 mm^-1, F（000） = 796, Z = 2, the final R= 0.0351 and wR = 0.0889 for 2387 obsevved reflections （Ⅰ 〉 2σ（Ⅰ））. In the crystal structures of 1 and 2, diverse supramolecular motifs from 1-D chains/ladders to 3-D networks are constructed from corresponding distinct [M^Ⅱ（H2O）8] ion clusters as the second building units, respectively. The solid state compounds of 1 and 2 show similar photoluminescent spectra with emission maximum at ca.     

Determination of pyrethroid pesticide residues in vegetables by solvent sublation followed by high-performance liquid chromatography

A novel method is developed for separating and enriching pyrethroid pesticides from vegetables by solvent sublation, and determination of the pyrethroids is performed by high-performance liquid chromatography (HPLC). The effects of organic solvent, pH of the solution, nitrogen flow rate, and sublation time on the sublation efficiency of pyrethroids are investigated in detail, and the optimal conditions of the solvent sublation are selected. The floated product of vegetables in the optimal conditions is determined by HPLC. The limit of detection values range from 1.4 microg/kg (for bifenthrin) to 4.2 microg/kg (for fenpropathin). The recoveries of spiked vegetable samples are from 85.7% to 110.4%, and relative standard deviation values are from 1.70% to 6.19%. The results are satisfactory.     

Formation and catalytic activity of spherical composites with surfaces coated with gold nanoparticles

Micelle-supported gold composites with a polystyrene core and a poly(4-vinyl pyridine)/Au shell are synthesized using NaBH(4) to reduce a mixture of micelle and HAuCl(4) in acidic aqueous solution (pH approximately 2). The template micelle with a polystyrene core and a poly(4-vinyl pyridine) shell is formed by self-assembly of block copolymer polystyrene-block-poly(4-vinyl pyridine). The gold nanoparticles coated onto the surfaces of the composites possess an average diameter of about 15 nm. The composites are applied to catalyze the reduction of p-nitrophenol in the presence of NaBH(4), and the results indicate that the kinetic constant of the reaction increases when the composite concentration and the reaction temperature increase. In addition, research results also indicate that composites with high content of gold show higher catalytic activity and higher catalytic efficiency.     

发光颜色可调的白磷钙矿结构Ca8MgBi(PO4)7∶Ce3+，Tb3+荧光粉的制备、发光性能及能量传递

采用具有白磷钙矿结构的磷酸盐作为目标产物,通过高温固相法制备了发光颜色可调的Ca₈MgBi(PO₄)₇∶Ce³⁺,Tb³⁺荧光粉。利用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)和荧光光谱等表征手段对其物相组成、微观形貌及发光性能进行了详细研究。结果表明：掺杂少量的Ce³⁺、Tb³⁺并没有改变Ca₈MgBi(PO₄)₇基质的晶体结构。荧光光谱和荧光寿命曲线确定了Ce³⁺-Tb³⁺之间存在能量传递,其能量传递机制为四极-四极相互作用,能量传递效率可达81%。固定Ce³⁺浓度而逐渐增加Tb³⁺的掺杂量时,系列Ca₈MgBi(PO₄)₇∶0.08Ce³⁺,yTb³⁺荧光粉的发...     

A sensitive DNA biosensor based on the distance dependent quenching of Silica@Ru(bpy)32+-chitosan-GO electrochemiluminescence by Ferrocene@Gold nanoparticles

A sensitive electrochemiluminescence (ECL) biosensor for the specific DNA sequence of hepatitis C virus (HCV) was developed based on the efficient quenching effect of the ferrocene cluster functionalized gold nanoparticles (Fc@AuNPs) on the ECL of electrodeposited silica@Ru(bpy)₃²⁺-chitosan-graphene oxide nanocomposite (SiO₂@Ru−CS−GO). Graphene oxide (GO) can accelerate electron transfer rate, thus improving the ECL of Ru(bpy)₃²⁺ on electrode surface. The molecular beacons (MB) was fixed to SiO₂@Ru−CS−GO by glutaraldehyde (GA) using the Schiff reaction between amino groups of chitosan (CS) and MB. The ECL of SiO₂@Ru−CS−GO was depressed greatly by the Fc@AuNPs labelled at the end of MB, then, a stronger ECL was observed when the distance between Fc@AuNPs and SiO₂@Ru−CS−GO increased after the hybridization of target DNA with MB. Under optimum conditions, the restored ECL intensity increased linearly with the target DNA concentration in the range of 1.0×10⁻¹⁶∼1.0×10⁻¹⁰ mol ⋅ L⁻¹, and the limit of detection (LOD) is 1.4×10⁻¹⁷ mol ⋅ L⁻¹. The proposed method exhibits acceptable stability and reproducibility. In general, the constructed HCV biosensor can be used for the sensitive detection of HCV in human serum, suggesting potential application prospects in bioanalysis.     

SMART: A data reporting standard for mass spectrometry imaging By Ying Xi,Alexandria L. Sohn,Alena N. Joignant,Stephanie M. Cologna,Boone M. Prentice and David C. Muddiman

Mass spectrometry imaging (MSI) is an important analytical technique that simultaneously reports the spatial location and abundance of detected ions in biological, chemical, clinical, and pharmaceutical studies. As MSI grows in popularity, it has become evident that data reporting varies among different research groups and between techniques. The lack of consistency in data reporting inherently creates additional challenges in comparing intra- and inter-laboratory MSI data. In this tutorial, we propose a unified data reporting system, SMART, based on the common features shared between techniques. While there are limitations to any reporting system, SMART was decided upon after significant discussion to more easily understand and benchmark MSI data. SMART is not intended to be comprehensive but rather capture essential baseline information for a given MSI study; this could be within a study (e.g., effect of spot size on the measured ion signals) or between two studies (e.g., different MSI platform technologies applied to the same tissue type). This tutorial does not attempt to address the confidence with which annotations are made nor does it deny the importance of other parameters that are not included in the current SMART format. Ultimately, the goal of this tutorial is to discuss the necessity of establishing a uniform reporting system to communicate MSI data in publications and presentations in a simple format to readily interpret the parameters and baseline outcomes of the data.     

Synthesis of Multifluoromethylated γ-Sultines by a Photoinduced Radical Addition–Polar Cyclization

Despite the significance of sultines in synthesis, medicine, and materials science, the chemistry of sultines has remained unexplored due to their inaccessibility. Herein, we demonstrate the development of a photoredox-catalyzed multifluoromethyl radical addition/SO₂ incorporation/polar cyclization cascade approach to multifluoromethylated γ-sultines. The reactions proceed by single electron transfer induced multifluoromethyl radical addition to an alkene followed by SO₂ incorporation, and single-electron reduction for polar 5-exo-tet cyclization. Key to the success of the protocol is the use of easily oxidizable multifluoroalkanesulfinates as bifunctional reagents. The reactions proceed with excellent functional-group tolerance to deliver γ-sultines in moderate to excellent yields.     

Ru(bpy)32+-Enabled Cell-Surface Photocatalytic Proximity Labeling toward More Efficient Capture of Physically Interacting Cells

Intercellular proximity labeling has emerged as a promising approach to enable the study of cell-cell interactions (CCIs), but the efficiency of current platforms is limited. Here, we use Ru(bpy)₃²⁺ to construct an efficient photocatalytic proximity labeling (PPL) system on the cell surface that allows the highly discriminative CCI detection with spatiotemporal resolution. Through the mechanism study and quantitative characterization on living cells, we demonstrate that the singlet-oxygen (¹O₂) mechanism is more efficient and specific than the single electron transfer (SET) mechanism in Ru-mediated PPL. Ru(bpy)₃²⁺ catalysts with different cell-anchoring moieties are prepared to facilitate the catalyst loading on primary cells. Finally, based on this system, we develop a “live” T cell receptor (TCR) multimer with TCR-T cells that could sensitively identify and discriminate cells presenting antigens of different affinity, providing a powerful tool to better understand the heterogeneity of antigen presenting cells.