The enzyme-amplified amperometric DNA sensor using an electrodeposited polymer redox mediator

A highly sensitive method for the detection of a breast cancer-associated BRCA-1 gene is reported. The detection is based on a classical sandwich-type assay using horseradish peroxidase (HRP) as a catalytic label and electrodeposited Os^2+/3+ conducting polymer (PAA-PVI-Os) as a redox mediator. Target DNA could be detected by the HRP-catalyzed reduction of H₂O₂, leading to a limit of detection as low as 10 fM. Supported by the National Natural Science Foundation of China (Grant Nos. 20725516, 20704043, 20873175 & 20805055), Shanghai Municipal Commission for Science and Technology (Grant Nos. 0752nm021 & 07ZR14136), Ministry of Science and Technology (Grant Nos. 2006CB933000, 2007CB936000 & 2007AA06A406), Ministry of Health (Grant No. 2009ZX10603), and China Postdoctoral Science Foundation and Shanghai Postdoctoral Scientific Program (Grant No. 07R214160).     

Complexation of two non-fully hydrogen bonded aromatic hydrazide heptamers toward <Emphasis Type="Italic">n</Emphasis>-octyl-α-L-glucopyranoside in chloroform

Two aromatic hydrazide haptamers have been prepared, with both consisting of two hydrogen bonded folded segments. Compared to their fully hydrogen bonded analogues, the flexibility of their backbones increases due to lack of one or two intramolecular hydrogen bonds at the middle aromatic unit. (2D) ¹H NMR, circular dichroism and fluorescent studies revealed that both oligomers moderately complex n-octyl-α-L-glucopyranoside in chloroform. Supported by the National Natural Science Foundation of China(Grant Nos. 20732007, 20621062, 20872167, and 20672137), the National Basic Research Project (Grant No. 2007CB808000) and the Chinese Academy of Sciences (Grant No. KJCX2-YW-H13)     

Unprecedented synthesis of chiral calix[4](aza)crowns and its potent encapsulating methanol

Unprecedented synthesis of chiral (aza)crown ethers of calix[4]arene derivatives bearing a carboxyl amide bridge was described. The synthesis proceeds through condensation of the corresponding dinitriles with optically active 1,2-aminoalcohols,and is catalyzed by the ZnCl2 Lewis acid at elevated temperature in a very efficient one-pot process. The cavity of calix[4](aza)crowns can encapsulate methanol molecules by O—H...π interaction,which has been confirmed by X-ray crystal structures and ESI-MS.     

Enantiopure inherently chiral calix[4]arene derivatives containing quinolin-2-yl-methanol moiety:Synthesis and application in the catalytic asymmetric addition of diethylzinc to benzaldehyde

A series of novel N,O-type chiral ligands derived from enantiopure inherently chiral calix[4]arenes containing quinolin-2-yl-methanol moiety in the cone or partial-cone conformation have been synthesized and characterized. Moreover, they have been applied to the catalytic asymmetric addition of diethylzinc to benzaldehyde, which represents the first example that the inherently chiral calixarene can be used as the chiral ligands for the catalytic asymmetric synthesis. Supported by the National Natural Science Foundation of China (Grant Nos. 20625206 & 20372064), the National Basic Research Project (Grant Nos. 2007CB808000 & 2008CB617501), and the Chinese Academy of Sciences     

Two novel interpenetrated zinc(II) and cadmium(II) coordination polymers based on 4-imidazole-benzoate: Syntheses,crystal structures and properties

Two novel interpenetrated coordination polymers, [Zn(IBA)₂] _n (1) and {[Cd(IBA)₂(H₂O)]·4H₂O} _n (2), have been synthesized by using 4-imidazole-benzoic acid (HIBA) as ligand under hydrothermal conditions. Complex 1 crystallizes in a chiral space group and has a two-fold interpenetrated 2D network structure with (4,4) topology, while complex 2 is a 3D porous dia network with four nets interpenetrating each other. The SHG activity of 1 and the photoluminescent property of 2 have been investigated. Supported by the National Natural Science Foundation of China (Grant Nos. 20731004 & 20721002) and the National Basic Research Program of China (Grant No. 2007CB925103)     

Colorimetric and electrochemical Pb<Superscript>2+</Superscript> detection by imine-bridged tetrathiafulvalene-pyridine derivatives

Imine-bridged TTF-π-pyridine derivatives, 2NTTF, 3NTTF and 4NTTF, were synthesized and the cation-binding study was performed. It is noted that with the addition of the micromolar concentration of Pb²⁺ to the solution, these compounds display remarkable changes in solution color, ¹H NMR spectra and electrochemical properties. The nitrogen atom of the imine-bridge in 2NTTF not only serves as a π-conjugated spacer but also participates in the sensing and coordinating properties. Supported by the National Natural Science Foundation of China (Grant Nos. 20732007, 20728506 & 20672122), the Ministry of Science and Technology of China (Grant Nos. 2006CB806105, 2007CB808004, 2007CB936001 & 2009CB-22008) and the Bureau for Basic Research of the Chinese Academy of Sciences     

Research of the relationship of intracellular acidification and apoptosis in Hela cells based on pH nanosensors

In this paper,the relationship of intracellular acidification and apoptosis in Hela cells induced by vin-cristine sulfate has been studied by use of the ratiometric pH nanosensors that have been developed by our group,employing fluorescein isothiocyanate(FITC) doped as the pH-sensitive dye and Tris(2,2'-bipyidyl) dichlororuthenium(II) hexahydrate(RuBpy) doped as reference dye. The pH change of the Hela cells induced by vincristine sulfate has been monitored in vivo,in situ and real time by use of the ratiometric pH nanosensors. The experimental results show that the pH of the apoptotic Hela cells induced by vincristine sulfate has been acidified from 7.11 to 6.51,and the percentage of intra-cellular acidification is correlated with the induced concentration and incubation time of the vincristine sulfate. The further study of the percentage of intracellular acidification and the percentage of apop-tosis of Hela cells at the same time reveals that apoptosis of Hela cells induced by vincristine sulfate is preceded by intracellular acidification. These results would provide theoretical foundation for the therapy of cancer through interfering the pH of cells by use of vincristine sulfate or other anti-cancer drugs.     

A new fluorescent sensor selective for Pb<Superscript>2+</Superscript> in water capable of two-photon-induced fluorescence measurement

A new fluorescent sensor (1) for Pb²⁺ containing a 1,4-dicyano-2,5-bis(styryl)benzene fluorophore and 2-(N,N′-bis(carboxylmethyl))amino-1-carboxylmethoxylbenzene as receptor has been synthesized. The sensor selectively responds to Pb²⁺ in the aqueous environment, and brings about similar and significant changes in one- and two-photon excited emission spectra: λ _max red-shift from 460 (519) to 590 nm. The selective response is pH-independent in a large physiological pH range, and two-photon action cross section (ϕδ) is 51 GM (1 GM = 1×10⁻⁵⁰ cm⁴·s·photon⁻¹·molecule⁻¹) at 740 nm. Supported by the National Natural Science Foundation of China (Grant Nos. 20705621 & 20706008), the National Basic Research Project of China (Grant No. 2009CB724706), the Ministry of Education of China, Changjiang Scholars Innovative Research Team in University (Grant No. IRT0711) and Cultivation Fund of the Key Scientific and Technical Innovation Project (Grant No. 707016)     

Michael addition reactions of cyclanones with acrylamides: Producing 2-carbamoylethyl derivatives or ene-lactams

The electron-withdrawing groups (EWGs) in the electrophilic alkenes employed in the Michael addition reaction are almost only CO2R, CN, COR, NO2, and SO2Ph. Although amides (CONR1R2) are also typical electron-withdrawing groups and are of great importance in organic synthesis, they are scarcely em-ployed as the EWGs of the electrophilic alkenes in the Michael addition reaction. In this work, the Mi-chael reactions of acrylamide and its derivatives with cyclanones were successfully carried out in the presence of enough radical inhibitors. The amide groups play a key role in producing the preferred products. The N-substituted acrylamides, including N-monosubstituted and N,N-disubstituted acryla-mides could react with cyclohexanone (CHn) to give the expected 2-carbamoylethyl derivatives; how-ever, acrylamide reacting with cyclohexanone only produced ene-lactam. Cyclanones also have effects on the products, while the ring size of cyclanones influences the reaction yield and the α-substituent decides the ratio of resulting isomeric ene-lactams.     

Molecular dynamics simulation study on zwitterionic structure to maintain the natural behavior of polyalanine13 in aqueous environment

Molecular dynamics simulations are applied to the initial stage of polyalanine13 conformational transi- tion from α-helix to random coil in aqueous environment and the interaction of polyalanine13 with zwitterionic and hydrophobic surfaces respectively in the same condition. The analysis of secondary structure, hydrogen bonds, RMSD, dihedral distribution, and the degree of adsorption are performed. The results show that zwitterionic structure maintains the natural behavior of polyalanine13 in water to a better extent, which should be an indirect proof of the hypothesis of "maintain of normal structure."     

Preparation of polystyrene-grafted titanate nanotubes by in situ atom transfer radical polymerization

This work successfully prepared nanohybrids by in situ atom transfer radical polymerization (ATRP) of styrene from titanate nanotubes (TNTs). Fourier-transform infrared (FT-IR), pronton nuclear magnetic resonance spectroscopy (1H NMR), and thermal gravimetric analysis (TGA) were used to verify the successful graft of polystyrene (PS) chains from TNTs. Transmission electron microscopy (TEM) dis-played that the obtained PS-g-TNTs nanohybrids had a core-shell structure of TNT core and PS shell. The grafted PS ...     

Preparation of polyacrylamide based monolith with immobilized pH gradient and its application for protein analysis

Monolithic materials were prepared in capillaries by in situ polymerization of acrylamide, glycidyl methacrylate and N,N′-memylenebisacrylamid in the presence of trinary porogens, including 1,4-butanediol, dodecanol and dimethyl sulphoxide. With Ampholine immobilized on the monolith by chemical bonding according to their pIs, the monolithic immobilized pH gradient (M-IPG) was prepared, and applied to the separation of four standard proteins. Compared with polyacrylate based M-IPG, the hydrophilicity of the new material was improved. It could not only avoid the adsorption of proteins, but also make the synthesized procedure simple, which showed great potential in the analysis of proteins.     

Adsorptive desulfurization of diesel with mesoporous aluminosilicates

Mesoporous aluminosilicates (MAS) bearing microporous zeolite units and mesoporous structures were synthesized by the hydrothermal method. Adsorptive desulfurization ability of model oil and hydrotreated diesel was studied. The effects of template concentration, crystalization time and calcination time were investigated. The desulfurization ability of adsorbents was improved by transitional metal ion-exchanging. The adsorptive desulfurization of diesel was carried out on a fixed-bed system. The results show that the adsorptive capacity is MAS>MCM-41>NaY. The improvement of desulfurization ability of MAS by Cu⁺ is more significant than that of Ag⁺. Supported by National Basic Research Program of China (Grant No. 2006CB202507), National High-tech R&D Program (Grant No. 2006AA02Z209), and the National Natural Science Foundation of China (Grant No. 20806086)     

Syntheses, structures and magnetic properties of a family of one-dimensional M(Ⅱ)-lanthanide(Ⅲ) (M =Ni(Ⅱ) and Zn(Ⅱ)) coordination polymers

A series of 1D nickel(Ⅱ)/zinc(Ⅱ)-lanthanide(Ⅲ) coordination polymers, [M(μ-L)2Ln(NO3)3]n· solvents (HL =bis(2-pyridylcarbonyl)amine; M = Ni, Ln = Gd (1 · NiGd), Tb (2· NiTb), Dy (3· NiDy), Ho (4· NiHo), Y (5· NiY);M = Zn, Ln =Gd (6· ZnGd), Tb (7· ZnTb), Dy (8· ZnDy), Ho (9· ZnHo); solvents = H2O or H2O-ethanol), was synthesized and characterized. All of the complexes are isostructural at 293 K and crystallize in the orthorhombic space group Fddd. Magnetic measurements were performed on 1-9, where weak ferromagnetic interaction is found in 1 · NiGd, ferromagnetic interaction in 2·NiTb and 3·NiDy, and antiferromagnetic interaction in 4· NiHo. A remarkable dc magnetic field dependence of ac susceptibilities was found in this series of complexes.     

Sulfonate-based fluorescent probes for imaging hydrogen peroxide in living cells

Based on the mechanism of H₂O₂-mediated hydrolysis of sulfonates, two fluorescein disulfonates compounds (FS-1 and FS-2) were designed and synthesized as the highly selective and sensitive fluorescent probes for imaging H₂O₂ in living cells. The probes were detected with elemental analysis, IR, ¹H NMR and ¹³C NMR. Upon reaction with H₂O₂, the probes exhibit strong fluorescence responses and high selectivity for H₂O₂ over other reactive oxygen species and some biological compounds. Furthermore, the sulfonate-based probes, as novel fluorescent reagents, are cell-permeable and can detect micromolar changes in H₂O₂ concentrations in living cells by using confocal microscopy. Supported by the National Basic Research Program of China (Grant No. 2007CB936000), the National Natural Science Funds for Distinguished Young Scholar (Grant No. 20725518), Major Program of the National Natural Science Foundation of China (Grant No. 90713019), the National Natural Science Foundation of China (Grant No. 20875057), the Natural Science Foundation of Shandong Province, China (Grant No. Y2007B02), and the Science and Technology Development Programs of Shandong Province, China (Grant No. 2008GG30003012)     

Highly sensitive and selective ratiometric fluorescent copper sensors: Different binding affinities modulated by three separate side chains of naphthalimide

A series of compounds 1-11 with different side chains of naphthalimide as fluorescent copper sensors were designed and synthesized. Compounds 1, 9, 10 and 11 presented a high selectivity to Cu2+ in a neutral aqueous environment. Here 1, 9 and 10 showed selectivity and affinity to Cu2+ with an association constant of about ～106. It gave somewhat response to Ag+, Co2+, Ni2+ and Fe2+ while 1 detected copper. 9 and 10 displayed better selectivity by changing their hydrophobic side chains to the hydrophilic ones...     

Adsorption of TTF,TCNQ and TTF-TCNQ on Au(111): An <Emphasis Type="Italic">in situ</Emphasis> ECSTM study

The adsorption and adlayer structures of tetrathiofulvalene (TTF), tetracyanoquinodimethane (TCNQ) and TTF-TCNQ on Au(111) have been systematically investigated by in situ electrochemical scanning tunneling microscopy (ECSTM) and cyclic voltammetry in 0.1 mol L⁻¹ HClO₄. All the three molecules were found to form well-ordered adlayers in the double-layer potential region of Au(111). For TTF and TCNQ adlayers, (6×3) and (4×7) structures have been observed, respectively. A structural transition was observed on TCNQ adlayer at potential negative of 0.08 V vs. the reversible hydrogen electrode (RHE), and induced a new phase with (3 × 12) structure. On the other hand, the charge transfer complex, TTF-TCNQ, self-organized into ordered domains with a lamellar structure different from those of the pure TTF and TCNQ adlayers on Au(111). Its packing arrangement was comparable to surface structures of either single crystal or thin film of TTF-TCNQ. Supported by the National Natural Science Foundation of China (Grant Nos. 20673121, 20733004 & 20821003), the National Key Project for Basic Research (Grant Nos. 2006CB806101 & 2006CB932100) and Chinese Academy of Sciences     

Electrochemical sensing of ATP with synthetic cyclophane as recognition element

A new electrochemical sensor for ATP with synthetic cyclophane stably attached onto single-walled carbon nanotubes (SWNTs) as the recognition elements is described. UV-vis and cyclic voltammetric results demonstrate that ATP may interact with the synthetic cyclophane recognition elements to form a stable adduct mainly through electrostatic, π-π stacking and donor-acceptor interactions. Such interactions eventually lead to a decrease in the peak currents of the cyclophane recognition elements attached onto t...     

3D-QSAR and docking studies of estrogen compounds based on estrogen receptor β

Close attention has been paid to estrogen compounds because these chemicals may pose a serious threat to the health of humans and wildlife. Estrogen receptor (ER) exists as two subtypes, ERα and ERβ. The difference in amino acids sequence of the binding sites of ERα and ERβ might lead to a result that some synthetic estrogens and naturally occurring steroidal ligands have different relative affinities and binding modes for ERα and ERβ. In this investigation, comparative molecular similarity indices analysis...