ABSTRACT
Water-soluble upconversion nanoparticles (UCNPs), based on polyvinylpyrrolidone (PVP)-coated NaYF4:Er3+,Yb3+,Gd3+, with various concentrations of Gd3+ ions and relatively high upconversion efficiencies, were synthesized. The internalization and cytotoxicity of the thus obtained UCNPs were evaluated in three cell lines (HeLa, HEK293 and astrocytes). No cytotoxicity was observed even at concentrations of UCNPs up to 50 µg ml-1. The fate of the UCNPs within the cells was studied by examining their upconversion emission spectra with confocal microscopy and confirming these observations with transmission electron microscopy. It was found that the cellular uptake of the UCNPs occurred primarily by clathrin-mediated endocytosis, whereas they were secreted from the cells via lysosomal exocytosis. The results of this study, focused on the mechanisms of the cellular uptake, localization and secretion of UCNPs, demonstrate, for the first time, the co-localization of UCNPs within discrete cell organelles.
ABSTRACT
Alternating poly(m-p-aniline) can be oxidized to radical cations with spins S = 1/2. For high spin density, ferromagnetic spin interaction is observed, and some of the generated radical cations are found to be in a ground triplet state.
ABSTRACT
The analysis indicated factors affecting caries prophylaxis and teeth treatment in children with mild mental retardation. The factors were sought in the personality of the child, its family environment and the work of the dentist. A significant effect on the cooperation of the dentist with the patient was exerted by such factors as the level of anxiety before dental procedure, motivation to treatment, intensity of teaching of oral hygiene, life period when teaching was started, frequency of teethbrushing, regular contacts with the dentist, and the mode of child reception by the dentist.
