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Liposomal forms of new antitumor drugs based on europium chelates examined by P-terphenyl fluorescence quenching
(Харьковский Национальный Университет им. В.Н.Каразина, 2010) Limanskaya, L.A.; Trusova, V.M.; Gorbenko, G.P.; Deligeorgiev, T.; Vasilev, A.; Kaloianova, S.; Lesev, N.
Europium chelates have been previously shown to possess pronounced cytotoxic activity. These compounds are of great interest for biomedical investigations and diagnostics, because their spectral characteristics are optimal for visualization of the occurred processes. Application of these pharmaceutical compounds in the free form is limited by their high toxicity and metabolic instability. In view of this, the development of the delivery systems for europium chelates becomes actual. Liposomes represent one of the most promising delivery systems, which allows to increase the efficiency of pharmacological agents. The use of liposomal formulations of antitumor drugs is currently in a focus of biomedical and biophysical research due to the following advantages: complete biocompatibility, ability to carry both lipophilic and hydrophilic compounds, protecting them from chemical degradation and transformation, decreased toxicity and increased therapeutic index of drug, etc. In the present work we explore the interaction between europium chelates (here referred to as V6 and V8) and model lipid membranes. Fluorescence intensity of membrane-incorporated probe p-terphenyl was found to decrease with enhancement of drugs concentration. The obtained results indicate that p-terphenyl fluorescence is quenched upon europium chelate incorporation into phosphatidylcholine liposomes. Quantitative characteristics of p-terphenyl fluorescence quenching by the drugs under consideration have been determined.
Partitioning of europium chelate into lipid bilayer as revealed by p-terphenyl and pyrene quenching
(Харьковский Национальный Университет им. В.Н.Каразина, 2010) Limanskaya, L.A.; Yudintsev, A.V.; Trusova, V.M.; Gorbenko, G.P.; Deligeorgiev, T.; Vasilev, A.; Kaloianova, S.; Lesev, N.
Fluorescence quenching method is an effective tool for obtaining important information about different properties of biophysical and biochemical systems. In the present study quenching of fluorescent probes p-terphenyl and pyrene by europium chelate were observed in phosphatidylcholine liposomes. Europium chelates (EC) belong to a new class of potential antitumor drugs with high cytotoxic activity. These compounds are of particular interest for biomedical investigations and diagnostics, since their spectral characteristics are optimal for decrease of light scattering in biological patterns and background signal. However, the application of such drugs in a free form is limited by their high toxicity and metabolic instability. One efficient way to increase drug efficiency is based on using different drug delivery systems such as liposomes. Highly adaptable liposome-based nanocarriers currently attract increasing attention, because of their advantages, viz. complete biodegradability, ability to carry both hydrophilic and lipophilic payloads and protect them from chemical degradation and transformation, increased therapeutic index of drug, flexibility in coupling with targeting and imaging ligands, improved pharmacodynamic profiles compared to the free drugs, etc. The present study was focused on examination of lipid bilayer interactions of europium chelate (here referred to as V10). Fluorescence intensity of membrane- incorporated probes – pyrene and p-terphenyl – was found to decrease with increasing concentration of the drug, suggesting that V10 represents an effective quencher for these probes. This finding was explained by the drug penetration into hydrophobic membrane core, followed by the collision between V10 and probe molecules and subsequent fluorescence quenching. The acquired fluorescence quenching data were quantitatively interpreted in terms of the dynamic quenching model.