Observation of electrostatically released DNA from gold electrodes with controlled threshold voltages

DNA oligo-nucleotides, localized at Au metal electrodes in aqueous solution, are found to be released when applying a negative bias voltage to the electrode. The release was confirmed by monitoring the intensity of the fluorescence of cyanine dyes (Cy3) linked to the 5' end of the DNA. The threshold voltage of the release changes depending on the kind of linker added to the DNA 3'-terminal. The amount of released DNA depends on the duration of the voltage pulse. Using this technique, we can retain DNA at Au electrodes or Au needles, and release the desired amount of DNA at a precise location in a target. The results suggest that DNA injection into living cells is possible with this method.     

Electronic Communication between S=1/2 Spins in Negatively‐charged Double‐caged Fullerene C60 Derivative Bonded by Two Single Bonds and Pyrrolizidine Bridge

Radical anion salt {cryptand[2.2.2] (K⁺)}₂(bispheroid)^2??3.5C₆H₄Cl₂ ( 1 ) of the double‐caged fullerene C₆₀ derivative, in which fullerene cages are linked by a cyclobutane bridging cycle and additionally by a pyrrolizidine moiety, was obtained. Each fullerene cage in this derivative accepts one electron on reduction, thus forming the (bispheroid)^2? dianions with two interacting S=1/2 spins on the neighboring cages. Low‐temperature magnetic measurements reveal a singlet ground state of the bispheroid dianions whereas triplet contributions prevail at increased temperature. An estimated exchange interaction between two spins J/k_B=?78 K in 1 indicates strong magnetic coupling between them, nearly two times higher than that (J/k_B=?44.7 K) in previously studied (C₆₀^?)₂ dimers linked via a cyclobutane bridge only. The enhancement of magnetic coupling in 1 can be explained by a shorter distance between the fullerene cages and, possibly, an additional channel for the magnetic exchange provided by a pyrrolizidine bridge. Quantum‐chemical calculations of the lowest electronic state of the dianions by means of multi‐configuration quasi‐degenerate perturbation theory support the experimental findings.     

NanoPARCEL: a method for controlling cellular behavior with external light

We developed a simple preparation procedure for the protein encapsulated nanoparticle and used the nanoparticle for spatiotemporal activity control of various proteins. We succeeded in the local protein activation within cells by light using the nanoparticle.     

Structural Elucidation of an Elicitor-Active Oligosaccharide,LN-3, Prepared from Algal Laminaran

Abstract

The primary structure of an elicitor-active oligosaccharide, LN-3, prepared from partially hydrolyzed algal laminaran was determined by means of the analyses of glycosyl-linkage, fragments by acetolysis, and glycosyl-sequence. The elicitor-active oligosaccharide, LN-3, is a pyridylaminated hepta-β-d-glucoside which was shown to have the following linear structure: β-d-Glcp(1→6)-β-d-Glcp(1→3)-β-d-Glcp(1→3)-β-d-Glcp(1→3)-β-d-Glcp(1→6)-β-d-Glcp(1→3)-Glc-PA.     

Carbon dioxide fixation by microalgae photosynthesis using actual flue gas discharged from a boiler

To mitigate CO₂ discharged from thermal power plants, studies on CO₂ fixation by the photosynthesis of microalgae using actual exhaust gas have been carried out. The results are as follows.

Magnitude and origin of the attraction and directionality of the halogen bonds of the complexes of C6F5X and C6H5X (X = I, Br, Cl and F) with pyridine

The geometries and interaction energies of complexes of pyridine with C₆F₅X, C₆H₅X (X=I, Br, Cl, F and H) and R_FI (R_F=CF₃, C₂F₅ and C₃F₇) have been studied by ab initio molecular orbital calculations. The CCSD(T) interaction energies (E_int) for the C₆F₅X–pyridine (X=I, Br, Cl, F and H) complexes at the basis set limit were estimated to be ?5.59, ?4.06, ?2.78, ?0.19 and ?4.37 kcal mol^?1, respectively, whereas the E_int values for the C₆H₅X–pyridine (X=I, Br, Cl and H) complexes were estimated to be ?3.27, ?2.17, ?1.23 and ?1.78 kcal mol^?1, respectively. Electrostatic interactions are the cause of the halogen dependence of the interaction energies and the enhancement of the attraction by the fluorine atoms in C₆F₅X. The values of E_int estimated for the R_FI–pyridine (R_F=CF₃, C₂F₅ and C₃F₇) complexes (?5.14, ?5.38 and ?5.44 kcal mol^?1, respectively) are close to that for the C₆F₅I–pyridine complex. Electrostatic interactions are the major source of the attraction in the strong halogen bond although induction and dispersion interactions also contribute to the attraction. Short‐range (charge‐transfer) interactions do not contribute significantly to the attraction. The magnitude of the directionality of the halogen bond correlates with the magnitude of the attraction. Electrostatic interactions are mainly responsible for the directionality of the halogen bond. The directionality of halogen bonds involving iodine and bromine is high, whereas that of chlorine is low and that of fluorine is negligible. The directionality of the halogen bonds in the C₆F₅I– and C₂F₅I–pyridine complexes is higher than that in the hydrogen bonds in the water dimer and water–formaldehyde complex. The calculations suggest that the C? I and C? Br halogen bonds play an important role in controlling the structures of molecular assemblies, that the C? Cl bonds play a less important role and that C? F bonds have a negligible impact.     

Method validation by interlaboratory studies of improved hydrophilic oxygen radical absorbance capacity methods for the determination of antioxidant capacities of antioxidant solutions and food extracts

Hydrophilic oxygen radical absorbance capacity (H-ORAC) is a method for evaluating antioxidant capacities of solutions of hydrophilic compounds. In this study, we improved the original method for H-ORAC determination, and evaluated the precision of the two improved methods (methods A and B) by interlaboratory studies using 5 antioxidant solutions and 5 food extracts as test samples. An interlaboratory study of method A, in accordance with the harmonized protocol, demonstrated satisfactory performance (intermediate precision relative standard deviations (RSD(int)) ranging from 4.6 to 18.8%; the reproducibility relative standard deviations (RSD(R)) ranging from 7.0 to 21.1%, and the HorRat values ranging from 0.40 to 1.93). However, methodological problems remained, and a further improved method, method B, was thus developed. An interlaboratory study of method B by 5 participating laboratories showed better intermediate precision and reproducibility (RSD(int) and RSD(R) ranging from 1.8 to 9.4%, and from 4.4 to 13.8%, respectively), and all HorRat values for the test samples were less than 1.3, suggesting good performance for the H-ORAC measurement.     

Blockade of inflammatory responses by a small-molecule inhibitor of the Rac activator DOCK2

1. Download : Download high-res image (273KB)
2. Download : Download full-size image

Highlights? CPYPP binds to DOCK2 DHR-2 domain and inhibits its catalytic activity ? CPYPP inhibits DOCK2-mediated Rac activation in cells ? The structural features of CPYPP required for its inhibitory effect were revealed ? CPYPP inhibits lymphocyte migration and activation in vitro and in vivo     

Effect of the cooling rate on dimerization of C60(•-) in fullerene salt (DMI+)2·(C60(•-))·{Cd(Et2NCS2)2I-}

The salt (DMI(+))(2)·(C(60)(?-))·{Cd(Et(2)NCS(2))(2)I(-)} (1) containing fullerene radical anions, the anions of cadmium diethyldithiocarbamate iodide, and N,N'-dimethylimidazolium cations was obtained. Fullerenes are monomeric in 1 at 250 K and form three-dimensional packing in which each fullerene has nearly tetrahedral surroundings from neighboring fullerenes. Fullerenes with a shorter interfullerene center-to-center distance of 10.031(2) ? form spiral chains arranged along the lattice c axis. The convolution consists of four fullerene molecules. Dimerization realized in 1 within the spiral chains below 135 K manifests a strong dependence on the cooling rate. The "frozen" monomeric phase was obtained upon instant quenching of 1. This phase is stable below 95 K for a long time but slowly converted to the dimeric phase at T > 95 K. It exhibits a weak antiferromagnetic interaction of spins below 95 K (the Weiss temperature is -4 K), which results in the splitting of the electron paramagnetic resonance (EPR) signal into two components below 10 K. A disordered phase containing both C(60)(?-) monomers and singly bonded (C(60)(-))(2) dimers with approximately 0.5/0.5 occupancies is formed at an intermediate cooling rate (for 20 min). The position of each fullerene in this phase is split into three positions slightly shifted relative to each other. The central position corresponds to nonbonded fullerenes with interfullerene center-to-center distances of 9.94-10.00 ?. Two other positions are coincided to dimeric fullerenes formed with the right and left fullerene neighbors within the spiral chain. This intermediate phase is paramagnetic with nearly zero Weiss temperature due to isolation of C(60)(?-) by diamagnetic species and exhibits a strongly asymmetric EPR signal below 20 K. A diamagnetic phase containing ordered singly bonded (C(60)(-))(2) dimers can be obtained only upon slow cooling of the crystal for 6 h.