Search

The molecular arrangement of the extremely uniaxial thin film was determined using X-ray analysis, including grazing incidence wide-angle X-ray scattering. The highly oriented film was obtained by depositing a bisazo dye onto an aligned polytetrafluoroethylene (PTFE) layer via vacuum evaporation, as shown previously. The X-ray analysis indicated that the molecules are arranged in parallel or antiparallel orientations within the unit cell. Moreover, their long axes are parallel to each other within the grains which are uniformly oriented throughout the film. These results confirm the driving force of the orientation reported previously using a molecular dynamics model: dye molecules trapped along the atomic grooves between adjacent PTFE chains serve as nuclei for crystal growth. In addition, the long molecular axes remain parallel to the rubbing direction, although some grains are inclined in the short-axis direction. This molecular arrangement in the film could contribute to a high degree of uniaxial orientation. [ABSTRACT FROM AUTHOR]

In nanoparticle-based drug delivery systems, dispersion stability is one of the most significant factors controlling drug efficacy and side effects. Herein, we synthesized guaiazulene derivatives-conjugated podophyllotoxin prodrugs and fabricated their nanoparticles (GA-CN-PPT nano-prodrugs). GA-CN-PPT nano-prodrugs were obtained with a size of about 100 nm and possessed high dispersion stability. The cytotoxicity was tunable by changing the length of the carbon chain linker. Notably, the release rate of PPT was the key factor for the anticancer activity of GA-CN-PPT nano-prodrugs. The nano-prodrugs could serve as a promising template for developing a novel delivery system using nano-prodrugs. [ABSTRACT FROM AUTHOR]

Nano-prodrug is a nanomedicine developed by the reprecipitation method, which allows nanoparticles to be fabricated by only prodrug molecules without using any nanocarriers. In the present study, we synthesized a heterodimer, composed of hinokitiol and podophyllotoxin (PPT) linked via different linkers of carbon chain length as new prodrug compounds, and fabricated their nano-prodrugs. We found that the longer the carbon chain linker, the smaller the size of nanoparticles, and the lower their cytotoxicity. We concluded that heterodimeric prodrugs can be fabricated into nano-prodrugs without reducing their drug loading capacity, and might eventually serve as a promising template for the development of novel nanomedicine. [ABSTRACT FROM AUTHOR]

Nanoscale surface patterns were observed in thin films of mexylaminotriazine-functionalized glasses containing polar groups upon the application of an electric field at temperatures over their glass transition temperatures (Tg). This phenomenon occurred due to the surface deformation process initiated by external electric field instabilities on the films. The minimal surface deformation temperature (Tdewet) relative to Tg was found to increase as a function of the polarity of the substituents and the surface pattern roughness was observed to increase linearly with temperature for a fixed electric field and exposure time. Reversal of the electrical field polarity and the use of both hydrophilic and hydrophobic substrates did not significantly change the surface deformation behavior of the films, which is due to the deposition of charges at the free interface. The application of a mask between the electric field electrodes allowed to selectively pattern areas that are exposed. Furthermore, it was observed that this surface deformation behavior was reversible, since heating the films to a temperature above Tg in the absence of an electric field caused the erasure of all surface patterns. [ABSTRACT FROM AUTHOR]

In order to find new ionic compounds with good characteristics for second harmonic generation (SHG), the relationship between first hyperpolarizabilities (β) and the position of the cationic center with respect to the benzene ring was investigated. The β values of a series of trimethylammonium cations: X–C6H4–(CH2)nN+(CH3)3, where X = H, CH3, OCH3, NH2, and N(CH3)2; n = 0–2, were calculated by using the MOPAC PM3 method. Relatively large calculated β values were obtained when X = N(CH3)2 and X = NH2. Series of [4-(dimethylamino)phenyl]trimethylammonium (X = N(CH3)2; n = 0) and [2-(4-aminophenyl)ethyl]trimethylammonium (X = NH2; n = 2) derivatives were synthesized. Among them, seven SHG-active complexes were found and four crystal structures were determined. [ABSTRACT FROM AUTHOR]