Synthesis and biological evaluation of novel neamine-nucleoside conjugates potentially targeting to RNAs

Eighteen novel neamine-nucleoside conjugates with ethylenediamine-lysine or ethylenediamine-arginine as the linker were synthesized and their potential binding to A site of 16S RNA and TAR RNA was evaluated using SPR (surface plasmon resonance). Compared with neamine, compounds 10i and 10q show 6.3 and 4.8 times potential in binding to A site of 16S RNA and eight and six times potential in binding to TAR RNA, respectively. According to the data of SPR, it indicates that amino acid residue and nucleobase moieties of the designed neamine-nucleosides conjugates exhibit the important contributions for the binding to A site of 16S RNA and TAR RNA. The molecular docking study on the interaction between the ligands and A site of 16S RNA is in agreement with the experimental data. The novel type of modification may provide a promising way for the development of neamine derivatives effectively targeting to RNAs.     

Catalytic Carbonylation and Carboxylation of Organosulfur Compounds via C−S Cleavage

Transition‐metal‐catalyzed carbonylation with CO gas occupies a privileged position in organic synthesis for the synthesis of carbonyl compounds. Although this attractive and useful chemistry has led many researchers to investigate carbonylative transformations of various organic (pseudo)halides, C?S‐cleaving carbonylation of organosulfur compounds has been fairly limited. Recently, a broad spectrum of C?S‐cleaving transformations has been emerging in the field of cross‐coupling. In light of the importance of carbonyl compounds as well as considerable advancement for employing organosulfur compounds as competent surrogates of (pseudo)halides, carbonylative transformations of C?S bonds should be of high value. This Minireview focuses on catalytic C?S carbonylation of organosulfur compounds with CO or its equivalents. In addition, reductive carboxylation of C?S bonds with CO₂ is described.     

Rationally Designed Three‐Layered Cu2S@Carbon@MoS2 Hierarchical Nanoboxes for Efficient Sodium Storage

Hybrid materials, integrating the merits of individual components, are ideal structures for efficient sodium storage. However, the construction of hybrid structures with decent physical/electrochemical properties is still challenging. Now, the elaborate design and synthesis of hierarchical nanoboxes composed of three‐layered Cu₂S@carbon@MoS₂ as anode materials for sodium‐ion batteries is reported. Through a facile multistep template‐engaged strategy, ultrathin MoS₂ nanosheets are grown on nitrogen‐doped carbon‐coated Cu₂S nanoboxes to realize the Cu₂S@carbon@MoS₂ configuration. The design shortens the diffusion path of electrons/Na⁺ ions, accommodates the volume change of electrodes during cycling, enhances the electric conductivity of the hybrids, and offers abundant active sites for sodium uptake. By virtue of these advantages, these three‐layered Cu₂S@carbon@MoS₂ hierarchical nanoboxes show excellent electrochemical properties in terms of decent rate capability and stable cycle life.     

Numerical analysis of the Gran methods. A comparative study

The paper concerns mainly the modified Gran methods, considered as extrapolative standard addition methods. Particularly, the approximation:

     

Nano Au/TiO2 hollow microsphere membranes for the improved sensitivity of detecting specific DNA sequences related to transgenes in transgenic plants

Gold nanoparticles (nano Au)/titanium dioxide (TiO₂) hollow microsphere membranes were prepared on the carbon paste electrode (CPE) for enhancing the sensitivity of DNA hybridization detection. The immobilization of nano Au and TiO₂ microsphere was investigated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization events were monitored with EIS using [Fe(CN)₆]^3−/4− as indicator. The sequence-specific DNA of the 35S promoter from cauliflower mosaic virus (CaMV35S) gene was detected with this DNA electrochemical sensor. The dynamic detection range was from 1.0×10⁻¹² to 1.0×10⁻⁸ mol/L DNA and a detection limit of 2.3×10⁻¹³ mol/L could be obtained. The polymerase chain reaction (PCR) amplification of the terminator of nopaline synthase (NOS) gene from the real sample of a kind of transgenic soybean was also satisfactorily detected. Supported by the National Natural Science Foundation of China (Grant Nos. 20635020 and 20375020), Doctoral Foundation of the Ministry of Education of China (Grant No. 20060426001) and Natural Science Foundation of Qingdao City (Grant No. 04-2-JZP-8)     

Electrochemical immunosensor designs for the determination of Staphylococcus aureus using 3,3-dithiodipropionic acid di(N-succinimidyl ester)-modified gold electrodes

The preparation of novel Staphylococcus aureus (S. aureus) amperometric immunosensing designs based on the covalent immobilization of RbIgG at gold electrodes using the heterobifunctional cross-linker 3,3-dithiodipropionic acid di(N-succinimidyl ester) (DTSP), are reported. Two different competitive immunosensing configurations have been tested and compared. In the first one, protein A-bearing S. aureus cells and HRP-labelled antiRbIgG compete for immobilized RbIgG binding sites, while in the second case HRP-labelled protein A was used. In both cases, the evaluation of the developed immunosensors performance was accomplished through the monitoring at 0.00 V (vs. Ag/AgCl) of the catalytic current originated after addition of hydrogen peroxide, using tetrathiafulvalene as redox mediator entrapped at the modified electrode surface by cross-linking with glutaraldehyde. Optimization of variables concerning the composition of the immunosensors as well as the detection conditions was carried out in 0.1 M NaAc/0.1 M NaCl buffer of pH 5.6. The configuration that employed antiRbIgG-HRP resulted in better analytical characteristics, with a detection limit of 1.4 × 10⁴ cells mL⁻¹ for S. aureus cells submitted to wall lyses by ultrasonic treatment. This immunosensor design was also evaluated using gold screen-printed electrodes in order to reduce the analysis time and cost. In this case, a limit of detection of 3.7 × 10² cells mL⁻¹ and a dynamic range from 1.3 × 10³ to 7.6 × 10⁴ cells mL⁻¹ was obtained. A RSD value of 10.5% was found for the responses to 9.6 × 10³S. aureus cells mL⁻¹ obtained with seven different Au/SPEs-immunosensors. These disposable immunosensors were applied to the quantification of S. aureus in milk spiked at two concentration levels, 1.2 × 10³ and 4.8 × 10³ cells mL⁻¹, with good recoveries.     

Synthesis and chiroptical properties of chiral binaphthyl‐containing polyfluorene derivatives

New chiral binaphthyl‐containing polyfluorene (PF) derivatives, PFOH , PFMOM , and PFP , bearing different binaphthyl units ((S)‐2,2′‐bis(methoxymethoxy)‐1,1′‐binaphthyl for PFMOM , (S)‐1,1′‐binaphthyl‐2,2′‐diol for PFOH , and (S)‐2,2′‐bis(diphenylphosphinyl)‐1,1′‐binaphthyl for PFP ) in the backbone have been designed and synthesized through Pd‐catalyzed Suzuki polycondensation. Their properties have been investigated in detail by ¹H NMR, ¹³C NMR, TGA, DSC, UV–vis, photoluminescence (in solutions, in thin films before and after annealing), and circular dichroism (CD) spectroscopic methods compared with poly(9,9‐dihexylfluorene‐2,7‐diyl) ( PF ). The resulting copolymers possessed excellent solubility in organic solvents and emitted strong blue light. The phosphine oxide‐containing copolymers PFP and PFMOM exhibited higher quantum yields and better thermal spectral stability in comparison with PF . All the copolymers exhibited obviously the linearly polarized photoluminescent properties both in solutions and in solid states. High emission polarization ratios (R_PL) of PFP were observed with no obvious decrease upon thermal annealing. In addition, investigation of the CD spectroscopic properties of these copolymers in THF solutions indicated that the chirality of the binaphthyls could be transferred to the whole PF backbone. All these results demonstrated that introduction of the chiral binaphthyls, particularly BINAPO, into the backbone could effectively improve the performances of the copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Fe_3(CO)_9(μ_3-S)_2的P(SR)Cl_2和P(SR′)_3取代物的合成和结构研究

用P(SR)Cl_2和P(SR′)_3作n-酸配体,分别与Fe_3(CO)_9(μ_3-S)_2进行取代反应,得到6种新的一取代产物Fe_3(CO)_8(μ_3-S)_2L和3种新的二取代产物Fe_3(CO)_7(μ_3-S)_2L_2,并对它们进行了IR、~1H NMR和MS表征,测定了其中一种取代物Fe_3(CO)_8(μ_3-S)_2[P(SC_6H_5)Cl_2]的分子和晶体结构。     

Two new dammarane-type triterpene sapogenins from Chinese red ginseng

Two new dammarane-type triterpene sapogenins were isolated from the Chinese red ginseng. The new sapogenins were named as 24,26-dihydroxy-panaxdiol (1) and 24-hydroxy-panaxdiol (2). Their structures were elucidated by the combined analysis of NMR and mass spectrometry as 20(S),25(R)-epoxydammarane-3β,12β,24β,26-tetraol (1) and 20(S),25-epoxydammarane-3β,12β,24α-triol (2). The complete signal assignments of the two compounds were carried out by 2D NMR spectral and NOE differential spectroscopy analysis.