KRUTIŠOVÁ Tereza Brno University of Technology

Hyaluronan and surfactant interact due to relatively strong electrostatic interactions between negative charge on hyaluronan chain and cationic parts of surfactant molecules. These interactions lead to complex nanoparticles formation which can be used in targeted delivery of hydrophobic active substances. These micellar aggregates have a core-shell like structure consisting of a hydrophobic inner core containing aggregated surfactant molecules and a hydrophilic hyaluronan shell layer. The aim of our study was to prepare hyaluronic acid nanoparticles based on electrostatic interactions with oppositely charged molecules and study stability of these particles under different conditions. Time and temperature stability, effect of ionic strength, effect of dilution of the system and effect of molecular weight of hyaluronan were investigated using fluorescence spectroscopy and dynamic light scattering methods. Fluorescent probe pyrene was selected for spectroscopy experiments because of its unique sensitivity to polarity of the medium. Particle size distributions of aggregates were obtained by dynamic light scattering measurements. Fluorescence and dynamic light scattering experiments indicate that hyaluronan-surfactant nanoparticles are influenced by a whole range of aspects, such as temperature, ionic strength of solution and storage time while molecular weight of hyaluronan affect these system at least. Dilution experiments show that our complex nanoparticles are insufficiently stable and are not able to maintain hydrophobic active substances in the inner core of aggregate after dilution of the system.