Influence of nanocrystal size on the in vivo absorption kinetics of caffeine after topical application.

The absorption of topically applied substances is challenging due to the effective skin barrier. Encapsulation of substances into nanoparticles was expected to be promising to increase the bioavailability of topically applied products. Since nanoparticles cannot traverse the intact skin barrier, but penetrate into the hair follicles, they could be used to deliver substances via hair follicles, where the active is released and can translocate independently transfollicularly into the viable epidermis. In the present in vivo study, this effect was investigated for caffeine. Caffeine nanocrystals of two sizes, 206 nm and 694 nm, with equal amounts of caffeine were used to study caffeine serum concentration kinetics after topical application on 5 human volunteers. The study demonstrated that at early time points, the smaller nanocrystals were more effective in increasing the bioavailability of caffeine, whereas after 20 min, the serum concentration of caffeine was higher when caffeine was applied by larger nanocrystals. Caffeine was still detectable after 5 days. The area under the curve could be increased by 82% when the 694 nm nanocrystals were applied. Especially larger sized nanocrystals seem to be a promising type of nanoparticulate preparation to increase the bioavailability of topically applied drugs via the transfollicular penetration pathway.

Surface-ionization methods and devices of indication and identification of nitrogen-containing base molecules.

The results of the development of methods and devices based on the effect of surface ionization (SI) and intended for the selective and sensitive registration and identification of the organic nitrogen base molecules in air and in mixtures of compounds for their chromatographic, ion mobility and mass-spectrometric analysis are presented. The main principles of the SI registration and identification of molecules are considered. The requirements that must be satisfied by devices implementing these principles are stated. The examples of the development of the effective and stable emitters, the simple-in-design diode SI detectors, the gas-chromatographic detectors, the SI gas analyzers of amines and the indicators and analyzers of narcotics including portable ones, SI ion mobility spectrometer and SI mass spectrometer are presented. They have a unique selectivity (up to 10(5)-10(8) with respect to organic solvents) and ionization efficiency (up to approximately 2 x 10(-1)) of amines and their derivatives, including the degradation products of chemical warfare agents, tobacco alkoloids, triazine herbicides, narcotics and other abused medicinal preparations, as well as the sensitivity of up to 6 C/g and picogram level detection limits with a response dynamic range of 5-8 orders of magnitude.

Surface ionization ion mobility spectrometry.

A surface ionization (SI) source was designed and constructed for ion mobility spectrometry (IMS). Compared with a conventional (63)Ni source, the surface ionization source is as simple and reliable, has an extended dynamic response range, is more selective in response, and does not have regulatory problems associated with radioactive ionization sources. The performance of this SI-IMS was evaluated with several different classes of compounds. Triethylamine was employed for studying the behavior of the ionization source under different source conditions and gaseous environments. Amines, tobacco alkaloids, and triazine herbicides were also investigated. Picogram level detection limits were achieved for target compounds with a response dynamic range of 5 orders of magnitude. Selective monitoring by IMS was also demonstrated. While the surface ionization source does not have the universality of response that is obtained with a (63)Ni ionization source, it is an excellent nonradioactive alternative for the ionization and ion mobility detection of those compounds to which it responds.