Living-cells cellular uptake

The advantageous effects of liposomal carrier systems include protection of compounds from metabolism or degradation, as well as enhanced cellular uptake. Liposome-mediated delivery of cytotoxic drugs to cells in culture has resulted in improved potency [58,59]. Prolonged release of encapsulated cargo has also been demonstrated [60,61]. More recently, liposomes with extended circulation half-lives and dose-independent pharmacokinetics (Stealth liposomes) [62] have shown promise in delivery of drugs that are normally very rapidly degraded. 

Parker and coworkers also reported a series of cationic, neutral, and anionic europium and terbium complexes containing a tetraazatriphenylene moiety (Figure 13.23) and investigated the interaction of these Eu(III) complexes with various living cells [66, 73, 74]. Interestingly, cellular uptake of either of the cationic complexes Tb-52 and Tb-57 is favored over uptake of the related neutral complex (Tb-53) and anionic complexes (Tb-54 and Tb-56) [66]. The cationic lanthanide complexes are taken up by mouse skin fibroblast (NIH/3T3) cells and tend... 

The trace elements include all inorganic elements found in living systems at very low concentration (picograms to micrograms per gram of cells or wet tissue). Some trace elements are essential for normal health and development others are toxic and still others have not been shown to be either. Chemically similar elements may compete for intestinal or cellular uptake or for metal binding sites on metalloenzymes and proteins. Interactions may also be complementary or synergistic. 

Chiu YL, Ali A, Chu CY, Cao H, Rana TM. Visuafizing a correlation between siRNA localization, cellular uptake, and RNAi in living cells. Chem Biol 2004 11 1165 1175. 

The prudent choice of appropriate side chain protecting groups for Lys and Arg did pose a particular problem in combination with the chemical stability of the metallocenes and available resins and linkers. In order to study cellular uptake and localization in the nucleus of living cells, derivatives of 36 and 37 with an additional fluorescent dye attached to the peptide were also prepared. Cellular uptake and localization of these conjugates was then followed in different cell lines by fluorescence microscopy. This is the first study of sub-cellular localization of organometaiiic peptide derivatives with non-radioactive metals (see also Section 5.5.3.2 below for an example ofa dual radiometal- and fluorescent-labeled peptide). 

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