engleski

Structural Study of Liposomes with Mannosylated 1- Aminoadamantane and Adamantyltripeptide

The aim of the present study was to investigate the structure of liposomes with encapsulated mannosylated 1-aminoadamantane and adamantyl- tripeptide (R)-N-(Adamant-1-yl)-3-, -D- mannopyranosyloxy-2-methyl propanamide and -D- Man-(R)-OCH2CH(CH3)CO-L-(adamant-2-yl)Gly-L-Ala-D- isoGln. Physicochemical properties such as liposome size, surface charge and surface modification have great influence on activity of liposomal formulations with encapsulated biologically active compound by targeting the drug carrier to the specific cell or tissue. We have previously shown the interaction of immunostimulating adamantyltripeptides (D/L- (adamant-2-yl)Gly-L-Ala-D-isoGln (Ad2TP1 and Ad2TP2) and phospholipids in liposomal bilayers 1. X-ray diffraction study revealed two sites of amantadine location within the bilayer, one site is close to the bilayer surface and the other is much deeper 2. Our hypothesis was: if the adamantane molecule, due to its liphophilic properties can penetrate into the lipid core of the bilayer, it might be possible that the hydrophilic part with the mannose molecule could be exposed on the liposome surface? In order to determine the size, shape and surface changes on the liposomes the dynamic light scattering (DLS) and atomic force microscopy (AFM) were used. The results have revealed that the shape and surface of liposomes with encapsulated examined compounds was changed in comparison to the empty liposomes. After the lectin Concavalin A (ConA) was added to the liposome preparation increase in liposome size and appearance of aggregates has been observed. The enlargement of liposomes was ascribed to the specific binding of the ConA to the mannose molecules present on the surface of the prepared vesicles. 1 Frkanec, R., Noethig-Laslo, V., Vranešić, B., Mirosavljević, K., Tomašić, J., Biochim Biophys Acta 1611 (2003) 187. 2 Duff, K.C., Cudmore, A.J., Bradshaw, J.P., Biochim Biophys Acta – Biomembranes 1145 (1) (1993) 149.

liposomes ; adamantane ; adamantyltripeptides ; mannose ; AFM ; DLS

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