The key role of water in the formation of cyclo(leucyl–leucyl) organogels was demonstrated. The conditions required for preparation of previously unknown gels with aliphatic hydrocarbons at room temperature were determined. Cyclo(leucyl–leucyl) self-assembles to form different structures depending on the medium used. The molecular organization of gels was studied by the methods of microscopy, spectroscopy and X-ray powder diffractometry. The organogel of cyclo(leucyl–leucyl) can reversibly change volume during the heating/cooling cycle. We showed the possibility of practical application of cyclo(leucyl–leucyl) for water purification. The results obtained give a new insight into the mechanism of gelation with cyclo(dipeptide)-based low-molecular-weight gelators and may be useful for the preparation of new physical gels.

Inhalation administration is a promising alternative to the invasive drug delivery methods. The particle size required for ideal drug aerosol preparation is between 1 and 3 μm. The application of microspherical particles of solid dispersions enhances bioavailability of poorly soluble drugs due to the solubilization. In the present work, the spray drying process of the production of microspherical particles of solid dispersions of polyvinylpyrrolidone K29-32 with model hydrophobic drug, phenacetin, was optimized using the results of DSC, PXRD, and viscometry. The diameter of the obtained particles is within 1–3 μm range. The Gibbs energy of dissolution in water was shown to be negative for the mixture with polymer/phenacetin mass ratio 5 : 1. We have demonstrated that the optimal size distribution for the inhalation administration is obtained for microspherical particles produced using spray caps with 7.0 μm hole size. The dissolution rates of phenacetin from the produced microspherical particles were faster than that of drug powder. As evidenced by powder X-ray diffraction data, phenacetin stayed in amorphous state for 4 months in microspherical particles of solid dispersions. According to the obtained results, strategic application of the spray drying process could be beneficial for the improvement of the pharmaceutical properties of model drug, phenacetin.

Textured nanocrystalline ZnO thin films are synthesized by ion beam assisted deposition. According to X-ray diffraction data, the crystallite size is ~25 nm. Thin (~15 nm) ZnO layers containing Ag...