Selective alkylation of T-T mismatched DNA using vinyldiaminotriazine-acridine conjugate.

The alkylation of the specific higher-order nucleic acid structures is of great significance in order to control its function and gene expression. In this report, we have described the T-T mismatch selective alkylation with a vinyldiaminotriazine (VDAT)-acridine conjugate. The alkylation selectively proceeded at the N3 position of thymidine on the T-T mismatch. Interestingly, the alkylated thymidine induced base flipping of the complementary base in the duplex. In a model experiment for the alkylation of the CTG repeats DNA which causes myotonic dystrophy type 1 (DM1), the observed reaction rate for one alkylation increased in proportion to the number of T-T mismatches. In addition, we showed that primer extension reactions with DNA polymerase and transcription with RNA polymerase were stopped by the alkylation. The alkylation of the repeat DNA will efficiently work for the inhibition of replication and transcription reactions. These functions of the VDAT-acridine conjugate would be useful as a new biochemical tool for the study of CTG repeats and may provide a new strategy for the molecular therapy of DM1.

Vinyldiaminotriazine-acridine conjugate as G-quadruplex alkylating agent.

Higher-order structures of nucleic acids have become widely noted for their biological consequences and the discovery of an alkylating small molecule for these structures has been of interest due to its therapeutic potential. We previously developed the vinyldiaminotriazine (VDAT)-acridine conjugate as a T-T mismatch alkylating agent. In this report, we focused on the finding of the alkylation to the G-quadruplex (G4) DNA with VDAT-acridine conjugates. The VDAT-acridine conjugates exhibited a considerable alkylation ability to G4 under mild conditions. Moreover, the investigation of properties with the alkylated G4 revealed that alkylation by this conjugate significantly increased the stability of the G4 structure. This study provides a starting point in the further development of selective G4 alkylating small molecules.

Mechanistic Study on Allylic Arylation in Water with Linear Polystyrene-Stabilized Pd and PdO Nanoparticles.

The catalytic cycle of allylic arylation in water catalyzed by linear polystyrene-stabilized Pd or PdO nanoparticles (PS-PdNPs or PS-PdONPs) was investigated. Stoichiometric stepwise reactions indicated that the reaction did not proceed stepwise on the surface of the catalyst. In the case of the reaction with PS-PdNPs, the leached Pd species is the catalytically active species and the reaction takes place through a similar reaction pathway accepted in the case of a complex catalyst. In contrast, allylic arylation using PS-PdONPs as a catalyst occurs via a Pd(II) catalytic cycle.

Lithium secondary batteries using modified-imidazolium room-temperature ionic liquid.

Highly reversible, safe lithium secondary batteries that use imidazolium-cation-based room-temperature ionic liquid as an electrolyte and lithium metal as an anode material were realized by the molecular design. To achieve higher reduction stability, an electron-donating substituent was introduced to promote charge delocalization in the imidazolium cation of room-temperature ionic liquids.

Highly reversible lithium metal secondary battery using a room temperature ionic liquid/lithium salt mixture and a surface-coated cathode active material.

For the purpose of realizing high-voltage, high-capacity, long-life and safe rechargeable batteries, a lithium secondary battery that uses high-voltage stable ZrO2-coated LiCoO2 cathode powder and a nonvolatile high-safety room temperature ionic liquid was fabricated.

Optical modeling of nanocrystalline TiO2 films.

The light transmittance, T, in nanocrystalline TiO2 films was studied as a function of the light wavelength, lambda, the nanocrystal radius, a, and the film thickness, d. Two types of TiO2 nanoparticles were employed: a commercial powder (P25) and synthesized particles from titanium isopropoxide (SP). The X-ray diffraction measurements revealed that both P25 and SP are mainly anatase and the average crystal sizes, 2a, of P25 and SP are 50.3 and 23.7 nm, respectively. Despite the visual difference between micron-order thin films of P25 and SP, the light hemispherical transmittance corrected with the surface specular reflectance has a clear dependence of ln(T) = -0.5beta lambda(-4)a(3)d, with beta = 1.5 x 10(3) from visible to near-infrared wavelengths. The dependence and beta value were successfully explained by the simplest model on the basis of the Rayleigh scattering theory. This indicates that the nanocrystalline TiO2 thin films are a typical medium where the simplest scattering model is a good approximation. However, the model was inapplicable to light scattering in relatively thick P25 films of 1.5-3.0 microm because of nonnegligible internal multiple scattering. For the moderate thickness films, ln(T) proportional to lambda(gamma), where gamma increases from -4 in proportion to the film thickness is an alternative approximation. With these light scattering models, the light absorption rate of the TiO2 crystal was successfully evaluated from experimental extinction rates.

A new strategy for site-specific alkylation of DNA using oligonucleotides containing an abasic site and alkylating probes.

Selective chemical reactions with DNA, such as its labelling, are very useful in many applications. In this paper, we discuss a new strategy for the selective alkylation of DNA using an oligonucleotide containing an abasic site and alkylating probes. We designed three probes consisting of 2-AVP as a reactive moiety and three kinds of binding moiety with high affinity to duplex DNA. Among these probes, Hoechst-AVP probe exhibited high selectivity and efficient reactivity to thymine bases at the site opposite an abasic site in DNA. Our method is potentially useful for inducing site-directed reactions aimed at inhibiting polymerase reactions.