Thermal stabilisation of the short DNA duplexes by acridine-4-carboxamide derivatives.

The short oligodeoxynucleotide (ODN) probes are suitable for good discrimination of point mutations. However, the probes suffer from low melting temperatures. In this work, the strategy of using acridine-4-carboxamide intercalators to improve thermal stabilisation is investigated. The study of large series of acridines revealed that optimal stabilisation is achieved upon decoration of acridine by secondary carboxamide carrying sterically not demanding basic function bound through a two-carbon linker. Two highly active intercalators were attached to short probes (13 or 18 bases; designed as a part of HFE gene) by click chemistry into positions 7 and/or 13 and proved to increase the melting temperate (Tm) of the duplex by almost 8°C for the best combination. The acridines interact with both single- and double-stranded DNAs with substantially preferred interaction for the latter. The study of interaction suggested higher affinity of the acridines toward the GC- than AT-rich sequences. Good discrimination of two point mutations was shown in practical application with HFE gene (wild type, H63D C > G and S65C A > C mutations). Acridine itself can also serve as a fluorophore and also allows discrimination of the fully matched sequences from those with point mutations in probes labelled only with acridine.

Amphiphilic Cationic Phthalocyanines for Photodynamic Therapy of Cancer.

Effective interaction with biomembranes is essential for activity of photosensitizers; however, majority of them are highly charged symmetrical species. Amphiphilic cationic phthalocyanines differing in bulkiness of substitution on lipophilic part (-H, -SMe, -StBu) were therefore prepared. Compounds had high singlet oxygen production (ΦΔ =0.38-0.46, DMSO), good fluorescence emission (ΦF =0.21-0.26, DMSO), and log P values ranging -0.07-1.1 (1-octanol/PBS). Study of interaction with liposomes revealed that also bulky -StBu derivatives are able to enter biomembranes. Detail in vitro studies (toxicity, subcellular localization, type of cell death, and morphology) were performed. Compounds were characterized by excellent EC50 values in range of dozens of nM (HeLa, EA.hy926, MCF-7, HCT116), which were dependent on drug-light interval and reached plateau after 4 h on HeLa cells. Well-balanced lipophilicity with ability to interact with biomembranes rank these derivatives among perspective photosensitizers, even for vascular-targeted PDT (VTP) since they kill EA.hy926 without any preincubation time.

Binding of an amphiphilic phthalocyanine to pre-formed liposomes confers light-triggered cargo release.

Liposomes are able to load a range of cargos and have been used for drug delivery applications, including for stimuli-triggered drug release. Here, we describe an approach for imparting near infrared (NIR) light-triggered release to pre-formed liposomes, using a newly-synthesized cationic, amphiphilic phthalocyanine. When simply mixed in aqueous solution with cargo-loaded liposomes, the cationic amphiphilic phthalocyanine, but not a cationic hydrophilic azaphthalocyanine, spontaneously incorporates into the liposome bilayer. This enables subsequent release of loaded cargo (doxorubcin or basic orange) upon irradiation with NIR light. The rate of release could be altered by varying the amount of photosensitizer added to the liposomes. In the absence of NIR light exposure, stable cargo loading of the liposomes was maintained. Introduction.