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ARTICLE INFO Keywords: Oplopanax horridus Phytochemistry Polyynes Oplopantriol A Falcarindiol Anticancer Cell cycle Apoptosis Structure-activity relationship ABSTRACT Oplopanax horridus is a plant native to North America. Previous reports have demonstrated [...]

Oxidative bursts from plants play significant roles in plant disease defense and signal transduction; however, it has not hitherto been investigated on individual living plant cells. In this article, we fabricated a novel sensitive electrochemical sensor based on electrochemical deposition of Pt nanoparticles on the surface of carbon fiber microdisk electrodes via a nanopores containing polymer matrix, Nation. The numerous hydrophilic nanochannels in the Nation clusters coated on the electrode surface served as the molecular template for the deposition and dispersion of Pt, which resulted in the uniform construction of small Pt nanoparticles. The novel sensor displayed a high sensitivity for detection of [H.sub.2][O.sub.2] with a detection limit of 5.0 x [10.sup.-9] M. With the use of this microelectrochemical sensor, the oxidative burst from individual living plant protoplasts have been real-time monitored for the first time. The results showed that oxidative burst from single protoplasts triggered by a pathogen analogue were characterized by quanta release with a large nmnber of 'transient oxidative microburst' events, and protoplasts from the transgenic plants biologically displayed better disease-resistance and showed a distinguished elevation and longer-lasting oxidative burst. 10.1021/ac901300b

ABSTRACT A particulate matter (PM) transport model is developed to investigate coarse PM ([PM.sub.10]), fine PM ([PM.sub.[2.5]]), and very fine PM ([PM.sub.1]) transport mechanisms in urban street canopies under low-wind [...]

The syntheses of several new 7-azaindolyl-, indolyl-, and 3-methylindolyl-functionalized starburst molecules that contain either a 1,3,5-triazine, a benzene, a 2,4,6-triphenyl-2,4,6-triazine, a 1,3,5-triphenylbenzene, a 2,4,6-tris(biphenyl)-1,3,5-triazine, or a 1,3,5-tris(biphenyl)benzene core have been achieved. The synthetic methods used for these new compounds involve mostly Ullmann condensation and Suzuki coupling reactions. The thermal properties of the new molecules have been found to be highly dependent on the molecular weight and the central core. Glass transition temperatures greater than 150 °C were observed for the large starburst molecules based on the 2,4,6-tris(biphenyl)-1,3,5-triazine or the 1,3,5-tris(biphenyl)benzene core. The new starburst molecules are luminescent in the violet-blue region in solution and in the solid state. The emission energy and the quantum efficiency were found to be highly dependent on the central core and the functional group. In general, the triazine-based molecules were found to have a smaller HOMO-LUMO energy gap than the benzene-based analogues. The triphenyltriazine- or triphenylbenzene-based molecules were found to display a higher emission quantum efficiency than the large tris(biphenyl)triazine- or tris(biphenyl)benzene-based molecules. Key words: 7-azaindolyl, indolyl derivative, triazine and benzene cores, starburst molecule, blue luminescence. On a realise la synthese de plusieurs nouvelles molecules a base d'indolyle, de 3-methylindolye et de 7-azaindolyle fonctionnalises qui donnent l'impression d'une explosion d'etoiles et qui contiennent comme partie centrale une 1,3,5-triazine, un benzene, un 2,4,6-triphenyl-2,4,6-triazine, un 1,3,5-triphenylbenzene, un 2,4,6-tris(biphenyl)-1,3,5-triazine ou un 1,3,5-tris(biphenyl)benzene. Les methodes de synthese utilisees pour ces nouveaux produits impliquent principalement des reactions de condensation de Ullmann et de couplage de Suzuki. On a trouve que les proprietes des nouvelles molecules dependent fortement du poids moleculaire et de la nature de la partie centrale. On a observe des temperatures de transition de verre superieures a 150 °C pour les grosses molecules qui donnent l'impression d'une explosion d'etoiles a base d'une partie centrale de 2,4,6-tris(biphenyl)-1,3,5-triazine ou de 1,3,5-tris(biphenyl)benzene. Tant en solution qu'a l'etat solide, les nouvelles molecules qui donnent l'impression d'une explosion d'etoiles sont luminescentes dans la region du violet-bleu. On a trouve que l'energie d'emission et l'efficacite quantique dependent fortement de la nature de la partie centrale et du groupe fonctionnel. On a trouve que, en general, l'ecart entre les energies des orbitales moleculaires hautes occupees (HO) et basses vacantes (BV) des molecules a base de triazine sont plus faibles que celles de leurs analogues a base de benzene. On a observe que les efficacites quantiques d'emission des molecules a base de triphenyltriazine ou de triphenylbenzene sont plus grandes que celles des molecules a base de tris(biphenyl)triazine ou de tris(biphenyl)benzene. Mots cles : 7-azaindolyle, derive de l'indolyle, partie centrale a base de triazine et de benzene, molecule qui donne l'impression d'une explosion d'etoiles, luminescence bleue. [Traduit par la Redaction], Introduction Starburst or star-shaped molecules have been shown to have the tendency to form amorphous films with a relatively high [T.sub.g], a property that is highly desired for applications of [...]

A novel microfluidic device has been developed for onchip transport, location, and quantal release monitoring of single cells. The microfluidic device consists of a plate of PDMS containing channels for introducing cells and stimulants and a glass substrate into which a cell microchamber was etched. The two tightly reversibly sealed plates can be separated for respective cleaning, which significantly extends the lifetime of the microchip that is frequently clogged in cell analysis experiments. Using hydraulic pressure, single cells were transported and located on the microfluidc chip. After location of a single PC12 cell on the microfluidic chip, the cell was stimulated by nicotine that was also introduced through the microchannels, and the quantum release of dopamine from the cell was amperometricly detected with our designed carbon fiber microelectrode. The results have demonstrated the convenience and efficiency of using the microfluidic chip for monitoring of quantal release from single cells and have offered a facile method for the analysis of single cells on microfluidic devices.

Microelectrode voltammetry has been considered to be a powerful technique for single biological cell analysis and brain research. In this paper, we have developed a simple method to get highly sensitive carbon fiber nanoelectrodes (CFNE) modified by single-walled carbon nanotubes (SWNTs) on the basis of our previous work. The electrochemical behavior of SWNTs/CFNE was characterized by potassium ferricyanide, dopamine (DA), epinephrine (E), and norepinephrine (NE) using cyclic voltammetry (CV). Compared with CFNE, SWNTs/CFNE has a much larger available internal surface area per external geometric area, which is supported by SEM images. The modified electrodes show very high sensitivity and favorable electrochemical behavior toward these neurotransmitters. The peak current increases lineary with the concentration of DA, E, and NE in the range of 1.0 x [10.sup.-7] -1.0 x [10.sup.-4], 3.0 x [10.sup.-7] -1.0 x [10.sup.-4], and 5.0 x [10.sup.-7] -1.0 x [10.sup.-4]M, respectively. The CV detection limits (S/N=3) of DA, E, and NE is 7.7 x [10.sup.-9], 3.8 x [10.sup-8] x 4.2 x [10.sup.-8]M, respectively. The modified electrode exhibited almost the same electrochemical behavior after 15 days, indicating that SWNTs/CFNE is pretty stable and has good reproducibility.

In electrophoresis, the migration velocity is used for sizing DNA and proteins or for distinguishing molecules based on charge and hydrodynamic radius. Many protein and DNA assays relevant to disease diagnosis are based on such separations. However, standard protocols are not only slow (minutes to hours) but also insensitive (many molecules in a detectable band). We successfully demonstrated a high-throughput imaging approach that allows determination of the individual electrophoretic mobilities of many molecules at a time. Each measurement only requires a few milliseconds to complete. This opens up the possibility of screening single copies of DNA or proteins within single biological cells for disease markers without performing polymerase chain reaction or other biological amplification. The purpose is not to separate the DNA molecules but to identify each one on the basis of the measured electrophoretic mobility. We developed three different procedures to measure the individual molecular mobilities. The results correlate well with capillary electrophoresis (CE) experiments for the same samples (2-49 kb dsDNA) under identical separation conditions. The implication is that any electrophoresis protocols from slab gels to CE should be adaptable to single-molecule screening for disease diagnosis.

A new and facile method has been developed for the fabrication of low-noise carbon fiber microelectrodes (CFMEs) and carbon fiber nanoelectrodes (CFNEs). The carbon fiber was flame-fuse sealed in the tip of the glass capillary. The CFMEs were made by cutting the protruding carbon fiber to the desired length, and the CFNEs were achieved by etching the protruding carbon on the flame to form a nanometer-scale tip. The tip of CFNEs can be controlled within the range from 100 to 300 nm. Thus, no epoxy wax was involved in the CFMEs and CFNEs. The experimental results of inspecting CFMEs and CFNEs by scanning electron microscopy demonstrated that the surface of the electrodes and the glass/fiber interface are very smooth. Therefore, the noise caused by the glass/ fiber of these electrodes is much lower than that of the electrodes fabricated conventionally. The electrodes were characterized by ferricyanide, catecholamine (dopamine,-DA), norepinephrine (NE), and epinephrine (E)) and 5-hydroxytryptamine (5-HT) neurotransmitters using CV, LSV, DPV, and FSCV. The results showed that the CFMEs and CFNEs have very excellent electrochemical behavior and high sensitivity. The CV and DPV detection limits of DA, NE, and E are 7.6 x [10.sup.-8], 7.0 x [10.sup.-8], and 5.0 x [10.sup.-8] mol/L, and the DPV detection limits of DA, NE, and E are 4.0 x [10.sup.-8], 1.0 x [10.sup.-7], and 2.2 x [10.sup.-7] mol/L, respectively. This experiment offers a new and facile method for the fabrication of CFMEs and CFNEs of very high sensitivity and low noise.