The aim of this thesis was to determine the solubilizing capacity of microbubbles based on SonoVue®, and phospholipids SonoVue® is made of, by using the UV-VIS spectrophotometry. The concentrations of solubilized substances within these systems was further determined. In particular, the properties of natrium dipalmitoylphosphatidylglycerole and distearoyl¬phosphatidylcholine were investigated. The microbubbles were produced using these phospholipids with the addition of polyethyleneglycol and palmitic acid. The solubilizing capacity was determined using hydrophobic solutes Sudan Red G, Oil Red O, 4-Di-2-Asp and Nile Red in order to obtain a model system of solubilized drugs or other hydrophobic substances. The behavior of solutes in phospholipids and our prepared microbubbles were examined in a moderately polar medium â physiological saline solution (0.15 M NaCl). The vizualization of prepared microbubbles was performed using optical and fluorescence microscopy. 4-Di-2-Asp, as a fluorescence probe, was not suitable for microbubble vizualization. The size of microbubbles that were produced during the experiment was almost the same as the size of microbubbles of commercially made SonoVue®. The concentration of solubilized hydrophobic solutes inside the liposomes of phospholipids ranged from tens to hundreds of micromoles per liter. With increasing concentration of phospholipids the concentration of solubilized solutes also increased. The results of this experiment can be used for further research focused on the solubilization of drugs in microbubbles, and contrast agents which are used in ultrasonography.

This work deals with preparation of microbubble suspension from a mixture of phospholipids, palmitic acid and polyethylene glycol. Properties of prepared systems were studied using bubble tensiometry and dynamic light scattering method and were compared with commercial contrast agent SonoVue®. Suspensions were prepared in various conditions including different atmosphere and increased temperature in some steps of preparation and different solution. Effect of polyethylene glycol addition on surface activity of the system was studied. Surface activity of phospholipids was insignificant. Surface tension decreased with increasing concentration and molecular weight of polyethylene glycol in the system. Effect of different atmosphere and increased temperature showed no substantial trend. It emerged that dynamic light scattering is not suitable for this type of samples because of high polydispersity and phase separation of the system.