Preparation of polystyrene-grafted titanate nanotubes by <Emphasis Type="Italic">in situ</Emphasis> 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) displayed that the obtained PS-g-TNTs nanohybrids had a core-shell structure of TNT core and PS shell. The grafted PS content was well controlled and increased with increasing of the monomer/initiator ratio. Further copolymerization of tert-butyl acrylate (tBA) from the surface of PS-g-TNTs was studied, illustrating the “living” characteristics of the surface-induced ATRP method used in this work. Supported by the Special Funds for Major State Basic Research Projects (Grant No. 2005CB623803), the National Basic Research Program (Grant Nos. 2007CB808000 & 2009CB930400), the National Natural Science Foundation of China (Grant Nos. 50633010 & 20874060), the Program for New Century Excellent Talents in University (Grant No. NCET-07-0558), the Basic Research Foundation of Shanghai Science and Technique Committee (Grant No. 07DJ14004), and Shanghai Leading Academic Discipline Project (Grant No. B202).     

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     

Field-effect transistor chemical sensors of single nanoribbon of copper phthalocyanine

Copper phthalocyanine (CuPc) nanoribbon field-effect transistors were implemented as chemical sensors. They showed fast response and high reversibility in the detection of the tetrahydrofuran atmosphere at room temperature. The drain current of the field-effect transistor sensor decreased from 6.7 to 0.2 nA when the transistor was measured under the tetrahydrofuran atmosphere. The sensor was self-refreshable in a few minutes. These results demonstrate that the organic single crystalline nanoribbon transistors could effectively act as chemical sensors. Supported by the National Natural Science Foundation of China (Grant Nos. 20721061, 50725311, 60736004, 60771031), the Ministry of Science and Technology of China (Grant Nos. 2006CB806200, 2006CB932100), and Chinese Academy of Sciences     

Synthesis of Fréchet-type dendritic homotriptycenes

A rapid and efficient synthesis of novel dendrimer homotriptycenes is presented. The dendronized 9,10-dihydroanthracen-9-ols 4, having high electron densities in the benzene rings of the Fréchet-type dendrons, exhibited in the presence of acid a quantitative transannular ring closure to the corresponding dendritic homotriptycenes. The electron-donating Fréchet-type dendrons enabled the intramolecular FC alkylation by a regioselective 1,7-elimination of H2O.     

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     

Recent developments in intelligent biomedical polymers

Intelligent polymers or stimuli-responsive polymers may exhibit distinct transitions in physical-chemical properties, including conformation, polarity, phase structure and chemical composition in response to changes in environmental stimuli. Due to their unique 'intelligent' characteristics, stimuli-sensitive polymers have found a wide variety of applications in biomedical and nanotechnological fields. This review focuses on the recent developments in biomedical application of intelligent polymer systems, s...     

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)     

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)     

Direct electrochemistry behavior of Cytochrome c on silicon dioxide nanoparticles-modified electrode

A newfangled direct electrochemistry behavior of Cytochrome c (Cyt c) was found on glassy carbon (GC) electrode modified with the silicon dioxide (SiO2) nanoparticles by physical adsorption. A pair of stable and well-defined redox peaks of Cyt c′ quasi-reversible electrochemical reaction were obtained with a heterogeneous electron transfer rate constant of 1.66×10-3 cm/s and a formal potential of 0.069 V (vs. Ag/AgCl) (0.263 V versus NHE) in 0.1 mol/L pH 6.8 PBS. Both the size and the amount of SiO2 nanoparticles could influence the electron transfer between Cyt c and the electrode. Electrostatic interaction which is between the negative nanoparticle surface and positively charged amino acid residues on the Cyt c surface is of importance for the stability and reproducibility toward the direct electron transfer of Cyt c. It is suggested that the modification of SiO2 nanoparticles proposes a novel approach to realize the direct electrochemistry of proteins.     

Photoelectrocatalytic oxidation of GMP on an ITO electrode modified with clay/[Ru(phen)<Subscript>2</Subscript>(dC18bpy)]<Superscript>2+</Superscript> hybrid film

An indium tin oxide (ITO) electrode modified with monolayer clay/[Ru(phen)₂(dC18bpy)]²⁺ (phen=1,10-phenanthroline, dC18bpy = 4,4′-dioctadecyl-2,2′ bipyridyl) hybrid film has been fabricated by the Langmuir-Blodgett (LB) method. Atomic force microscopy revealed that the single-layered hybrid film of clay/[Ru(phen)₂(dC18bpy)]²⁺ (denoted as Clay-Ru) was closely packed at a surface pressure of 25 mN·m⁻¹ and had a thickness of 3.4±0.5 nm. Cyclic voltammograms showed that the redox current of Ru(II) complex decreased when incorporated into the clay film, suggesting that the clay layer acts as a barrier against electron transfer. When applied to oxidizing the mononucleotide of guanosine 5′-monophosphate (GMP), a large catalytic oxidative current was achieved on the Clay-Ru(II) modified ITO electrode at the external potential above 900 mV (vs. Ag|AgCl|KCl) and, more significantly, this response was further enhanced by light irradiation (λ>360 nm), in which the photocurrent is increased about 11 times in comparison with that of a bare ITO. Mechanism of the photoelectrocatalytic effect was proposed in terms of the reduction of the photoelectrochemically generated Ru(III) complex in the Clay-Ru film by GMP. Supported by the National Natural Science Foundation of China (Grant Nos. 20471043 and 20843007), Zhejiang Provincial Natural Science Foundation (Grant Nos. Y404118 and Y408177), the “151” Distinguished Person Foundation of Zheji-ang Province of China, Zhejiang Technology Project Foundation (Grant No. 2007C21134) and Wenzhou Technology Project Foundation (Grant No. N2004B040)     

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.     

Effects of charge distribution on water filling process in carbon nanotube

Using umbrella sampling technique with molecular dynamics simulation, we investigated the nanofluidic transport of water in carbon nanotube (CNT). The simulations showed that a positive charge modification to the carbon nanotube can slow down the water column growth process, while the negative charge modification to the carbon nanotube will, on the other hand, quicken the water column growth process. The free energy curves were obtained through the statistical process of water column growth under different charge distributions, and the results indicated that these free energy curves can be employed to explain the dynamical process of water column growth in the nanosized channels. Supported by the National Natural Science Foundation of China (Grant Nos. 10425420 and 20773145), the Ministry of Science and Technology of China (Grant Nos. 2006CB806200 and 2006CB932100), and the Chinese Academy of Sciences including its CNIC Supercomputer Center.     

Design of artificial nucleases and studies of their interaction with DNA

The design of artificial nucleases and nuclease mimics has attracted extensive attention and made great progress due to their significant scientific meanings and potential application in the field of gene medicine and molecular biology. This paper reviews recent progress in the investigation of artificial nuclease, including “bifunctional cooperative catalysis”, “dinuclear synergistic catalysis”, “metal-free catalysis”, and especially, the studies of aza-crown ethers as artificial nucleases and their interaction with DNA. Supported by the National Natural Science Foundation of China (Grant Nos. 20872061 & 20372032) and the National Basic Research of China (Grant No. 2007CB925103)     

One-step direct synthesis of mesoporous aluminosilicates Al-SBA-15 with cage-like macropores by using micrometer-sized aluminum balls

Ordered mesoporous aluminosilicate Al-SBA-15 materials with cage-like macropores have been synthesized by using micrometer-sized aluminum balls as an Al source, tetraethyl orthosilicate (TEOS) as a silica source, and triblock copolymer Pluronic P123 as a template. The resulting materials were fully characterized by XRD, N₂ adsorption, SEM, TEM, ICP-AES, and ²⁷Al MAS-NMR. The products (Al-SBA-15) have ordered two-dimensional (2-D) hexagonal mesostructures (space group p6mm). The calcined Al-SBA-15 materials exhibit disordered macropores with diameters of about 70–80 nm and ordered mesopores with a diameter of ∼5 nm, a BET surface area of about 500 m²/g, Si/Al ratio of 40–80, and a ratio of tetrahedral Al to octahedral Al sites of about 2:1. This combination of properties gives these materials potential applications in areas such as adsorption, catalysis and separation. Supported by the National Natural Science Foundation of China (Grant Nos. 20890123 & 20721063), Shanghai Science & Technology Committee (08DZ2270500), and Shanghai Leading Academic Discipline Project (No.B108)     

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)     

Study on conductance of supersaturated chloride microdroplets

By using the measuring system previously designed by the authors, the conductance of KCl, NaCl and NH₄Cl microdroplets is obtained in the whole measuring RH range, especially in the supersaturation region, which cannot be acquired from the bulk solutions and fills the gap of lack of experimental data of conductance under the supersaturated state. The ERH and DRH of these three kinds of microdroplets observed from a microscope are 80.5% and 95.4% (KCl), 75.7% and 93.3% (NaCl), and 69.9% and 96.6% (NH₄Cl), respectively. In addition, it can be found from the dependence of conductance on RH that conductance is very sensitive to the existence of water molecules inside the microdroplet and the threshold of the deliquescence process can be predicted by the variation of conductance. Supported by the National Natural Science Foundation of China (Grant Nos. 20673010 and 20605004), Fundamental Research Foundation of BIT (Grant No. 20060742003), Program of Introducing Talents of Discipline to Universities (Grant No. B07012), and China Postdoctoral Science Foundation (Grant No. 20070410467)     

Synthesis,structure and nonlinear optical properties of two novel two-photon absorption chromophores

Two triphenylamine-based derivatives that can be used as two-photon absorption chromophore,tris{4-[4-(3-trifluoromethyl-3-oxopanoyl)]phenyl}amine (1) and tris{4-[4-(3-phenyl-3-oxopanoyl)] phenyl} amine (2) were successfully synthesized and fully characterized by elemental analysis,IR,1H NMR and MS. The single crystal X-ray diffraction analysis showed that the molecules possess D-(π-A)3 structures. One-and two-photon absorption and fluorescence in various solvents were experimentally investigated. A data rec...     

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)     

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."     

Honeycomb-patterned films of polystyrene/poly(ethylene glycol): preparation,surface aggregation and protein adsorption

Highly ordered honeycomb-patterned polystyrene (PS)/poly(ethylene glycol) (PEG) films were prepared by a water-assisted method using an improved setup, which facilitated the formation of films with higher regularity, better reproducibility, and larger area of honeycomb structures. Surface aggregation of hydrophilic PEG and adsorption of bovine serum albumin (BSA) on the honeycomb-patterned films were investigated. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to observe the surface morphologies of the films before and after being rinsed with water. As confirmed by the FESEM images and the AFM phase images, PEG was enriched in the pores and could be gradually removed by water. The adsorption of fluorescence-labeled BSA on the films was studied in visual form using laser scanning confocal microscopy. Results clearly demonstrated that the protein-resistant PEG was selectively enriched in the pores. This water-assisted method may be a latent tool to prepare honeycomb-patterned biofunctional surfaces. Supported by the National Natural Science Foundation of China (Grant No. 50803053), the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No. 50625309), the National Postdoctoral Science Foundation of China (Grant Nos. 20070421172 & 20081466) and the National Undergraduate Innovative Test Program