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Fluorescently-tagged lipids are a powerful tool for investigating the dynamics of lipids in cell biological studies and in biophysical applications. Herein we report the synthesis and the characterization of a new bola amphiphile, PC12, based on a bisimidic perylene moiety: a central perylene unit is symmetrically linked to two aliphatic chains both ending with a quaternary ammonium group. Absorption and fluorescent properties of the newly synthesized compound were investigated in DMSO and in water as a function of concentration and temperature. Further, the entrapment efficiency, the fluorescence behavior in dimyristoyl-sn-glycero-phosphocholine (DMPC) liposomes, and cell uptake on human and murine glioblastoma cell lines were evaluated. When loaded in liposomes, PC12 follows the same destiny of liposomes themselves in the cell cultures: this is an interesting result because PC12 could be used both as an aspecific dye (free form) and as an organelle-specific lipid probe.

Previous studies indicate that some perylene bisimide derivatives can drive the assembly of DNA G-quadruplexes, thus suggesting the possible advantage in the adoption of perylene-conjugated G-rich oligonucleotides in biological and biotechnological applications. Nevertheless, the typical poor solubility of perylene bisimides strongly limits the number of suitable chemical strategies to prepare perylene-conjugated oligonucleotides. In order to overcome these difficulties, we employed the earlier described core twisted perylene derivatives possessing unique optical and electronic properties, besides good solubility in common solvents. As a first result, the large-scale synthesis of a new dibromoperylene derivative (PEOEBr) phosphoramidite building block is herein reported. Furthermore, the structural behavior of the conjugated PEOEBr-GGGTTAGGG (HTRp2) human telomeric repeat was investigated by using CD, UV, fluorescence, and gel electrophoresis techniques in desalted water and in K(+)- and Na(+)-containing buffers. We observed that the peculiar property of PEOEBr moieties to form dimers instead of extended aggregates drives the HTRp2 strands toward dimerization and mainly promotes the formation of quadruplex species having both the 5'-ends located at the same side of the structures. However, the counterions present in solutions (K(+) or Na(+)) as well as the strand concentration, also contribute to influence the topology and the stoichiometry of formed structures. Furthermore, unlike the unmodified sequence GGGTTAGGG (HTR2), HTRp2 strands quickly associate into G-quadruplexes even in desalted water, as assessed by CD experiments.

Most known perylene diimides are lipophilic, with few exceptions of hydrophilic derivatives. Even in the latter case, the compounds have limited water solubility and show a strong tendency to self-aggregation. In this paper we present the synthesis of four new perylene derivatives with three and four basic side chains, obtained by functionalizing the bay-area of perylene. These molecules show great solubility in aqueous media as hydrochlorides and their tendency to self-aggregate is remarkably reduced with respect to the previously synthesized two-chained perylene diimides. Their different spectroscopic properties in various solvents and conditions are reported and discussed.