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New side-armed ligands of lariat ether type 6-13 have been synthesized by the respective phenolysis and naphtholysis reactions of the parent isomeric ansa (2,4) and spiro (3,5) macrocyclosubstituted cyclophosphazenes of general formula N3P3CldO(CH&H~0),] (where n = 4,5), separated by column chromatograhy, and characterized by mass spectrometry and IH and 31P NMR spectroscopies. The synthesized side-armed ligands 6-13, as well as their respective functional chlorine-containing precursors 2-5, represent crown ethers with cyclophosphazene subunits and may thus be considered as diphosphaza[l6lcrown-6 or PNP16C6 (2,6,10), diphosphaza[19lcrown-7 or PNP19C7 (4,8,12), phospha[l4]crown-5 or P14C5 (3,7, 111, and phospha[l7lcrown-6 or P17C6 (5,9, 13). The one-pot method of synthesis developed for (aryloxy)-crowns 6-13, with the phenolysis (or naphtholysis) performed in situ immediately after completing the formation of the respective chlorine-containing macrocycles 2-5, made it possible to obtain high yields of the corresponding 16-and 19-membered ansa-PNP-cyclosubstituted side-armed diphosphaza-crowns PNP16C6 and PNP19C7 (6,8,10,12) and to isolate the stable 14-and 17-membered spiro-P derivatives P14C5 and P17C6 (7,9, 11,13), inaccessible by other synthetic routes. The diphosphaza-crowns thus obtained with B-naphthoxy substituents (10,121 offer promising prospects as new ligands of the P-pivot lariat ether type, capable of complexing both alkali and transition metal cations and of potential catalytic activity in phase and electron-transfer processes.

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Hybridization to RNA is important for many applications, including antisense therapeutics, RNA interference, and microarray screening. Similar thermodynamic stabilities of A-U and G-U base pairs result in difficulties in selective binding of matched and mismatched RNA duplexes. Moreover, A-U pairs are weaker than G-C pairs so that binding is sometimes weak when many A-U pairs are present. It is known, however, that replacement of uridine with 2-thiouridine significantly improves binding and selectivity. To test for additional improvement of binding and of the specificity for binding A over G, LNA-2-thiouridine was synthesized for the first time and incorporated into many LNA-2-O-methylRNA/RNA duplexes. UV melting was used to measure the thermodynamic effect of replacing 2'-O-methyluridine with 2'-O-methyl-2-thiouridine or LNA-2-thiouridine. The 2-thiouridine usually enhances binding and selectivity. Selectivity is optimized when a single 2-thiouridine is placed at an internal position in a duplex.

In recent years, significant progress has been observed in the field of skin bioprinting, which has a huge potential to revolutionize the way of treatment in injury and surgery. Furthermore, it may be considered as an appropriate platform to perform the assessment and screening of cosmetic and pharmaceutical formulations. Therefore, the objective of this paper was to review the latest advances in 3D bioprinting dedicated to skin applications. In order to explain the boundaries of this technology, the architecture and functions of the native skin were briefly described. The principles of bioprinting methods were outlined along with a detailed description of key elements that are required to fabricate the skin equivalents. Next, the overview of recent progress in 3D bioprinting studies was presented. The article also highlighted the potential applications of bioengineered skin substituents in various fields including regenerative medicine, modeling of diseases, and cosmetics/drugs testing. The advantages, limitations, and future directions of this technology were also discussed.