Impact and mechanism of TiO_2 nanoparticles on DNA synthesis in vitro

The impact of TiO2 nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied. The impact of TiO2 nanoparticles on DNA synthesis was investigated by adding TiO2 nanoparticles in different sizes and at various concentrations into the polymerase chain reaction (PCR) system. TiO2 nanoparticles were premixed with the DNA polymerase, the primer or the template, respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis. Sequentially the interaction be- tween TiO2 nanoparticles and the DNA polymerase, the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis (PAGE). The results suggest that TiO2 nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than mi- croscale TiO2 particles at the equivalent concentration and the inhibition effect of TiO2 nanoparticles is concentration dependent. The molecular mechanism of such inhibition is that in the dark, TiO2 nanoparticles interact with the DNA polymerase through physical adsorption while TiO2 nanoparticles do with the primer or the template in a chemical adsorption manner. The disfunction levels of the bio-molecules under the impact of TiO2 nanoparticles are in the following order: the primer > the tem- plate > the DNA polymerase.     

Application of in-plasma catalysis and post-plasma catalysis for methane partial oxidation to methanol over a Fe_2O_3-CuO/γ-Al_2O_3 catalyst

Methane partial oxidation to methanol (MPOM) using dielectric barrier discharge over a Fe2O3-CuO/γ-Al2O3 catalyst was performed.The multicomponent catalyst was combined with plasma in two different configurations,i.e.,in-plasma catalysis (IPC) and post-plasma catalysis (PPC).It was found that the catalytic performance of the catalysts for MPOM was strongly dependent on the hybrid configuration.A better synergistic performance of plasma and catalysis was achieved in the IPC configuration,but the catalysts packed in the discharge zone showed lower stability than those connected to the discharge zone in sequence.Active species,such as ozone,atomic oxygen and methyl radicals,were produced from the plasma-catalysis process,and made a major contribution to methanol synthesis.These active species were identified by the means of in situ optical emission spectra,ozone measurement and FT-IR spectra.It was confirmed that the amount of active species in the IPC system was greater than that in the PPC system.The results of TG,XRD,and N2 adsorption-desorption revealed that carbon deposition on the spent catalyst surface was responsible for the catalyst deactivation in the IPC configuration.     

Polyethylenimine （PEI）-g-comb-poly（ethylene glycol）-transferrin（Ⅰ）： Tumor-targeted Vector for Gene Delivery In.vitro

The work described the synthesis and evaluation of PEI-g-comb-PEG-transferrin as a potential system for gene therapy in vitro. The MW of PEG was 10KDa, and PEI was 2KDa. Its structure was identified by NMR, FT-IR and TGA spectroscopy. MTT assay found that at concentration up to 4000 n mol/L of the polymer, cell viability was over 85%. The bio-character of polymer/DNA complex was characterized by agarose gel electrophoresis, ethidium bromide exclusion and zeta-potential assay. The polymer could retardate DNA at N/P ratio 3.0-3.5 （mol/mol）. The particle size of the polymer/DNA complex was less than 300 nm. Transfection efficiency of the complex was studied in COS7 and NT2 cell lines.     

PREPARATION OF LOW MOLECULAR WEIGHT POLY（GLYCIDYL METHACRYLATE） BY PHOTOPOLYMERIZATION

Low molecular weight poly（glycidyl methacrylate）s （PGMAs） were prepared by photopolymerization in ethyl acetate, with benzophenone （BP） as photoinitiator, and triethylamine （TEA） as hydrogen donor. The existence of semipinacol dormant end groups in PGMA was confirmed by FT-IR and ^1H-NMR, and the content of the semipinacol dormant groups was determined quantitatively by ^1H-NMR measurement. The effects of various thctors, such as reaction time, BP concentration and monomer concentration on the synthesis of the polymers were investigated systematically. The molecular weights of the polymers were also investigated with GPC. It is shown that increasing BP concentration and decreasing irradiation time and monomer concentration led to a significant decrease of the molecular weights.     

环糊精与两种有机物的包合物的不同光解特性

The effectiveness of the solubilization and photodegradation of β-cyclodextrin （β-CD） and hydroxypropyl-β- cyclodextrin （HPCD） on two hydrophobic organic compounds （HOC） of methyl parathion and pentachlorophenol was investigated. The results indicate that the solubilization or photodegradation of two HOC were influenced by complexing with β-CD or HPCD. The solubility of pentachlorophenol （PCP） was increased linearly with β-CD concentration. The solubility of methyl parathion （MPT） was increased with the increase of β-CD concentration initially, however, as the β-CD concentration was enhanced above 3 g/L, the solubility was decreased with increase of β-CD concentration. The solubilities of two HOC were increased linearly with the increase of HPCD concentration. Although the photodegradation of MPT was improved, the photodegradation of PCP was restrained by complexation of HOC with β-CD or HPCD. In a word, the effectiveness of photodegradation or solubilization of HPCD was more significant than that of β-CD. One potential application of such a method was the in situ remediation of hydrophobic organic pollutants in contaminated soil and groundwater or industrial waste streams.     

Sunlight photocatalytic degradation of ofloxacin using UiO-66/wood composite photocatalysts

This study synthesized UiO-66（Zr） in situ on wood via a one-step solvothermal method. UiO-66/wood was successfully prepared and its catalytic performance for the ofloxacin（OFX） photodegradation under simulate sunlight was also explored. Ui O-66/wood exhibited a better catalytic performance, and its degradation rate constant was about 1.2 and 1.5 times than that of UiO-66 and wood, respectively. The effects of solution initial concentration, pH of the system and dosage of the photocatalyst were e...     

ESR STUDY OF PLASMA-TREATED POLYTETRAFLUOROETHYLENE FILMS

The plasma treatment of polytetrafluoroethylene (PTFE) films was carried out in a capacitively coupled reactor with external electrodes. The free radicals generated in the process of treatment were detected by ESR techniques. The ESR spectra tended to indicate that the free radicals of the pLasma-treated PTFE film sample were turned into peroxy radicals on exposure to air. The extrema separation (W) of the ESR spectrum of the peroxy radical increased with the lowering temperature and underwent a sudden change within the temperature range of 170 to 190K. The ESR spectrum observed at 77K was quite different from that observed at room temperature. Finally, the effects of treatment time, input power and system pressure on radical concentration of the treated samples were studied. The attenuation of the peroxy radical at room temperature was also investigated.     

微波场中A型分子筛及分子筛膜合成的研究

Effects of aging time and alkalinity as well as cation concentration(Na⁺) on the synthesis of A type zeolite and zeolite membrane were investigated in this paper. The results showed that aging time for synthesis of A type zeolite and zeolite membrane had remarkable influence and alkalinity could accelerate the formation of zeolite but was disadvantage to zeolite membrane synthesis. Cation concentration(Na⁺) also couldn′t accelerate the synthesis of zeolite and zeolite membrane but it was probable an important factor to accelerate crystal growth .Moreover, more compact zeolite membranes could be synthesized by this method while the thickness of membrane was thinner than that of convention. Zeolites and zeolite membranes were characterized by XRD, TEM as well as IR characterization techniques.     

High Photocatalytic Properties of Zinc OxideNanoparticles with Amidoximated BacterialCellulose Nanofibers as Templates简

The freshly prepared water-wet amidoximated bacterial cellulose （Am-BC） serves as an effective nanoreactor to synthesis zinc oxide nanoparticles by in situ polyol method. The obtained ZnO/Am-BC nanocomposites have been characterized by field emission scanning electron microscopy （FE-SEM）, X-ray diffraction （XRD）, Fourier transformed infrared spectroscopy （FTIR） and thermogravimetric analysis （TGA）. The influence of the zinc acetate concentration on the morphologies and size ofZnO nanoparticles and the possible formation mechanism were discussed. The results indicated that uniform ZnO nanoparticles were homogeneously anchored on the Am-BC nanofibers through strong interaction between the hydroxyl and amino groups of Am-BC and ZnO nanoparticles. The loading content of ZnO nanoparticles is higher using Am-BC as a template than using the unmodified bacterial cellulose. The resultant nanocomposite synthesized at 0.05 wt% shows a high photocatalytic activity （92%） in the degradation of methyl orange.     

Sulfonated carbon materials with hydrophilic and lipophilic properties

Two acidic carbon materials （H-PRC and HS-C） were used as catalysts for the condensation reaction of methanol with formaldehyde to produce dimethoxymethane （DMM） in aqueous solution （hydrophilic system） and for the etherification of isopentene with methanol to produce tert amyl methyl ether （TAME） in toluene solution （lipophilic system）. Microcalorimetric adsorptions of water and benzene showed that the HS-C was highly hydrophilic without the lipophilicity, while the H-PRC exhibited both the hydrophilicity and lipophilicity. Thus, the HS-C was well dispersed in aqueous solution and difficult to separate from it. On the other hand, the H-PRC was highly active, more active than the acidic resin （D008） and sulfuric acid, for the synthesis of DMM in aqueous solution. The H-PRC was also highly active, more active than the HS-C, for the etherification of isopentene with methanol to produce TAME in toluene solution, probably owing to its amphiphilic surface property as well as its strong surface acidity as measured by the microcalorirnetric adsorption of NH3.     

Reactive adsorption of aminosilane onto the glycidyl methacrylate graft‐copolymerized poly(tetrafluoroethylene) film surface for adhesion enhancement with evaporated copper

Surface modification of argon‐plasma‐pretreated poly(tetrafluoroethylene) (PTFE) film via UV‐induced graft copolymerization with glycidyl methacrylate (GMA) was carried out first. Reactive adsorption of γ‐aminopropyltriethoxysilane (APS) onto the GMA graft‐copolymerized PTFE (GMA‐g‐PTFE) film surface was performed by the simple immersion of the film in the APS solution. The adsorption process was studied as a function of the APS concentration, the immersion time of the graft‐modified PTFE film in the APS solution, and the washing protocol. The chemical composition and morphology of the silane‐modified surfaces were characterized by X‐ray photoelectron spectroscopy and atomic force microscopy, respectively. The performance of the silane‐modified PTFE surface in adhesion promotion was investigated. The T‐peel adhesion strength of the evaporated Cu on the PTFE film with the reactively adsorbed organosilane increased significantly to about 12.5 N/cm. This adhesion strength was more than twice that of the assembly involving evaporated Cu on the GMA‐g‐PTFE film and about 10 times that of the assembly involving evaporated Cu on the Ar‐plasma‐treated PTFE film. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 80–89, 2000     

Electropolymerization of DBSA‐doped polypyrrole films on PTFE via an electroless copper interlayer

We report on the electroless deposition of thin films of copper on poly(tetrafluoroethylene) (PTFE) and their use as substrates for electropolymerization of polypyrrole. Argon plasma‐treated PTFE films were modified by silanization using N‐[3(trimethoxysilyl)propyl]diethylenetriamine (TMS). The TMS‐modified PTFE films were subsequently activated by PdCl₂ for the electroless deposition of copper. The omission of the commonly used SnCl₂ sensitization step represents a significant process enhancement with environmental and cost benefits. The surface composition of the substrate (before and after surface treatments) and overlayer films was studied using high‐resolution x‐ray photoelectron spectroscopy. A combination of time‐of‐flight secondary ion mass spectrometry and water contact‐angle measurements was also used to study the PTFE surface after argon plasma treatment. The Cu/PTFE films were used as substrates for subsequent pyrrole electropolymerization in aqueous dodecylbenzene sulphonic acid (DBSA) solution. The DBSA‐doped polypyrrole overlayers were successfully deposited on the Cu/PTFE surface using a constant applied potential of 1.5 V. The resulting material exhibited a doping level of 39%, determined using chemical component analysis of the N 1s photoelectron peak. Copyright © 2003 John Wiley & Sons, Ltd.     

One‐Pot Four‐Component Synthesis of Tetrasubstituted Pyrroles

A convenient one‐pot four‐component synthesis of tetrasubstituted pyrroles was carried out through the reaction of butane‐2,3‐dione with α‐aminophosphorous ylides, obtained in situ from the 1 : 1 : 1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylate, and ammonium acetate.     

A Facile Synthesis of 1‐Substituted 3‐Alkoxy‐1H‐isoindoles Based on the Reaction of 2‐(Dialkoxymethyl)phenyllithiums with Nitriles,Followed by Acid‐Catalyzed Cyclization

A two‐step synthesis of 1‐substituted 3‐alkoxy‐1H‐isoindoles 4 has been developed. Thus, the reaction of 2‐(dialkoxymethyl)phenyllithium compounds, which are easily generated in situ by Br/Li exchange between 1‐bromo‐2‐(dialkoxymethyl)benzenes 1 and BuLi in THF at ?78°, with nitriles afforded [2‐(dialkoxymethyl)phenyl]methanimines 2 , which were treated with a catalytic amount of TsOH?H₂O in refluxing CHCl₃ to give the desired products in reasonable yields. Similarly, 3‐aryl‐1‐ethoxy‐1‐methyl‐1H‐isoindoles 7 have been prepared starting from 1‐bromo‐2‐(1,1‐diethoxyethyl)benzenes 5 .     

Synthesis of well‐defined aromatic polyesters by chain‐growth polycondensation under suppression of transesterification

For the synthesis of aromatic polyesters with defined molecular weights and narrow molecular weight distributions (MWDs), we investigated the chain‐growth polycondensation of active amide derivatives of 4‐hydroxybenzoic acid, 1a and 1b , having an octyl or 4,7‐dioxaoctyl side chain, respectively. To suppress the transesterification of the polymer backbone with the monomer, the polymerization of 1 was carried out in tetrahydrofuran (THF) at −30 °C in the presence of initiator 2 and Et₃SiH/CsF/18‐crown‐6, which generated a hydride ion as a base in situ. The number‐average molecular weight (M_n) of poly 1a was controlled, and narrow MWDs were maintained, until the [ 1a ]₀/[ 2 ]₀ feed ratio was 14.3 (M_n ≤ 3500), whereas that of poly 1b was controlled until the feed ratio was 30 (M_n ≤ 7250). The difference stemmed from the higher solubility of poly 1b in THF. This chain‐growth polycondensation was applied to the synthesis of a diblock copolyester of 1a and 1b of a defined architecture. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4109–4117, 2005     

Colorimetric detection of polynucleotides on polypropylene slices.

The gold-label-silver-stain method (GLSS) for DNA hybridization detection has been receiving increased interest as a colorimetric detective method, demonstrating the advantages of non-radioactivity, non-quenching effect of fluorescence and simplicity for analytical equipment. A colorimetric detection based on the GLSS method was applied to DNA arrays in situ synthesized on polypropylene (PP) slices. In this paper a simple plasma treatment was employed to graft amino (-NH2) on the polypropylene slice surfaces, where DNA probes were immobilized via in situ synthesis. Hybridization was accomplished by a sandwich hybridization format. With the amplification of Silver Enhancer Solution, the hybridization signals were recorded with a scanner. A target DNA concentration as low as 100 fM was detected. Complementary and mismatched sequences were clearly distinguished, and the ratio of the background-subtracted gray scale values for a perfect match, single-base mismatch, 2-base mismatch and 3-base mismatch is 22:16:9:4. The sensitivity of the in situ synthesis system was 3 orders of magnitude higher than that of the spotting system, and the signals of the former were about 2-times stronger than that of the latter under the same target DNA concentration.     

Sequence‐Specific DNA Alkylation Targeting for Kras Codon 13 Mutation by Pyrrole–Imidazole Polyamide seco‐CBI Conjugates

Hairpin N‐methylpyrrole‐N‐methylimidazole polyamide seco‐CBI conjugates 2 – 6 were designed for synthesis by Fmoc solid‐phase synthesis, and their DNA‐alkylating activities against the Kras codon 13 mutation were compared by high‐resolution denaturing gel electrophoresis with 225 base pair (bp) DNA fragments. Conjugate 5 had high reactivity towards the Kras codon 13 mutation site, with alkylation occurring at the A of the sequence 5′‐ACGTCACC A ‐3′ (site 2), including minor 1 bp‐mismatch alkylation against wild type 5′‐ACG C CACC A ‐3′ (site 3). Conjugate 6 , which differs from conjugate 5 by exchanging one Py unit with a β unit, showed high selectivity but only weakly alkylated the A of 5′‐ACGTCACC A ‐3′ (site 2). The hairpin polyamide seco‐CBI conjugate 5 thus alkylates according to Dervan′s pairing rule with the pairing recognition which β/β pair targets T–A and A–T pairs. SPR and a computer‐minimized model suggest that 5 binds to the target sequence with high affinity in a hairpin conformation, allowing for efficient DNA alkylation.     

Surface‐initiated atom transfer radical polymerization from porous poly(tetrafluoroethylene) membranes using the C?F groups as initiators

This work reports the surface‐initiated atom transfer radical polymerization (ATRP) from hydrogen plasma‐treated porous poly(tetrafluoroethylene) (PTFE) membranes using the C? F groups as initiators. Hydrogen plasma treatment on PTFE membrane surfaces changes their chemical environment through defluorination and hydrogenation reactions. With the hydrogen plasma treatment, the C? F groups of the modified PTFE membrane surface become effective initiators of ATRP. Surface‐initiated ATRP of poly(ethylene glycol) methacrylate (PEGMA) is carried out to graft PPEGMA chains to PTFE membrane surfaces. The chain lengths of poly(PEGMA) (PPEGMA) grafted on PTFE surfaces increase with increasing the reaction time of ATRP. Furthermore, the chain ends of PPEGMA grown on PTFE membrane surfaces then serve as macroinitiators for the ATRP of N‐isopropylacrylamide (NIPAAm) to build up the PPEGMA‐b‐PNIPAAm block copolymer chains on the PTFE membrane surfaces. The chemical structures of the modified PTFE membranes are characterized using X‐ray photoelectron spectroscopy. The modification increases the surface hydrophilicity of the PTFE membranes with reductions in their water‐contact angles from 120° to 60°. The modified PTFE membranes also show temperature‐responsive properties and protein repulsion features owing to the presence of PNIPAAM and PPEGMA chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2076–2083, 2010     

Effect of maleic anhydride‐grafted polytetrafluoroethylene on the tensile and tribological properties of blending polytetrafluoroethylene with polyamide‐6

Blending polytetrafluoroethylene (PTFE) to polyamide‐6 (PA6) with and without maleic anhydride‐grafted polytetrafluoroethylene (PTFE‐g‐MA) was produced in a corotating twin screw extruder, where PTFE acts as the polymer matrix and PA6 as the dispersed phase. The effect of PTFE‐g‐MA on the tensile properties and tribological propertiesof PTFE/PA6 polymer blends is studied. Results show that the structural stability and morphology of the blends were greatly improved by PTFE‐g‐PA6 grafted copolymers, which were formed by the in situ reaction of anhydride groups with the amino end groups of PA6 during reactive extrusion forming an imidic linkage. The presence of PTFE‐g‐PA6 in the PTFE continuous phase improves the interfacial adhesion, as a result of the creation of an interphase that was formed by the interaction between the formed PTFE‐g‐PA6 copolymer in situ and both phases. Compared with thePTFE/PA6 without PTFE‐g‐MA, the PTFE/PA6 with PTFE‐g‐MAhad the lowest friction coefficient and wear under given applied load and reciprocating sliding frequency. The interfacial compatibility of the composite prevented the rubbing‐off of PA6, accordingly improved the friction and wear properties of the composite. Copyright © 2009 John Wiley & Sons, Ltd.     

An efficient in situ reduction and cyclization reaction for synthesis of spiro compound derivatives in Fe–H2O–AcOH medium from nitro compounds

An efficient in situ reduction and cyclization reaction for the synthesis of nitrogen‐containing spiro compounds directly form 5‐nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole in Fe–H₂O–AcOH medium is reported. 5‐Nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole were first used to synthesize spiro compounds, and this is a novel method for the synthesis of spiro compounds from nitro compounds. The advantages of this reaction are stable reagents, easily available raw materials, wide range of substrates and high yields.