Our Publications Database

Liposomes, Gentamicin, Microwaves, Fluorescence, Generalized polarization, Phase transition

Liposomes are largely used today as drug carriers. Their behavior in various chemical and physical environments should be well known in view of a rational design of vesicles of appropriate formulations. We investigated the liposomal membrane behavior under different physical and chemical conditions such as exposure to antibiotics, radiofrequecy fields and thermal changes. Measuring the Generalized Polarization of laurdan-labeled liposomes in the presence of the charged aminoglycoside gentamicin, under exposure to 2.45 GHz and under cyclic variation of temperature, the phase transition behavior of the phospholipids was characterized.

Reactive oxygen species, 2’,7’-Dichlorodihydrofluorescein acetate, Microvolumetric fluorospectrometer.

Detecting reactive oxygen species (ROS) in living cells is a difficult task because of their short lifetime, presence of cellular antioxidants, risk of cell death and unwanted transformations of the detector substance. Fluorescence-based techniques are currently most widely used, with high sensitivity and easy processing of samples but the classical instruments need a high amount of samples and consumables. We optimized and validated a microvolumetric fluorescence-based method for ROS detection in living cells, using 2’,7’-dichlorodihydrofluorescein acetate (H2DCFDA) and a microvolumetric fluorospectrometer. In our experimental conditions we determined that a measurement volume of 3 µL containing between 125 and 500 cells was sufficient for a reliable measurement of oxidized 2’,7’-dichlorofluorescein fluorescence. The method was applied on H2O2 and catalase treated MEF k41 cells. The catalase preloaded cells presented a lower fluorescent signal under H2O2 stress. Our results show that this microvolumetric method is suitable for oxidative stress specific detection even when compounds able to discriminate the various molecular categories of ROS are added. The measurements could be performed with high accuracy, demonstrating that the microvolumetric method provides a sensitive, fast and cost-effective means for ROS detection in living cells.

Liposome delivery, Active targeting, Functionalized liposomes, Apob100, Endocytosis

Liposomes can be modified and functionalized with different ligands to control their biological properties, such as longevity, targeting ability, and intracellular penetration, in a desired fashion (for example in photodynamic therapy). The aim of this study was to obtain functionalized liposomes with apolipoprotein ApoB100 ligand to achieve active intracellular targeted delivery via LDL-receptor, by naturally occurring endocytotic pathway. Human malignant melanoma A375 cells were used as model cells for in vitro evaluation of cellular endocytosis efficiency. The functionalized ApoB100-liposomes were incubated with cultured cells. Incubation periods of 2 and 4 hours were used to obtain ligand-receptor cellular endocytosis and fluorescence expression was evaluated. The functionalized liposomes displayed remarkably higher intracellular transfection efficiency comparatively to simple liposomal suspension. Liposomes functionalized with ApoB100 protein could function as excellent active targeting ligands and could be promising vectors for active targeted photosensitizer delivery in photodynamic therapy.