Nanostructured lipid carriers (NLC) are stable colloidal formulations with notable advantages for drug delivery systems. Thanks to their physicochemical stability, biocompatibility, biodegradability and controlled drug release, they have received increasing attention for the last several years. The aim of the study was to prepare and characterize nanostructured lipid carriers (NLC). Both, the effect of the process parameters and the effect of the preemulsion composition on the NLC properties were investigated. In the work, different type of surfactants (i.e. decyl glucoside, Poloxamer188, Tween 80, sodium cholate) and their combinations were used to stabilize NLC dispersions. Moreover, several kinds of solid lipids (modified beeswax, gliceryl behenate, cetyl palmitate and berry wax) and liquid lipids (caprilic/capric triglyceride and decyl oleate) were applied. An ultrasonication method using a probe type sonicator was used to obtain NLC, and the time and energy of the process were modified throuhout. The physicochemical properties of the formulations, such as particle size, size distribution, polidispersity index were studied using the dynamic light scattering (DLS) method. The electrophoretic mobility of obtained particles was also measured, using the Zetasizer Nano ZS Malvern Instrument based on the Laser Doppler Velocimetry (LDV) technique. Knowing the value of electrophoretic mobility of particles for given conditions, the zeta potential was determined. The obtained results showed that the process parameters and the composition of the preemulsion had significant impact on the nanoparticles structure. The optimal formulations size ranged between 60 and 80 nm, and the value of their zeta potential was up to -30mV. The stability of these systems was further confirmed by macroscopic observation.

The application of nanoemulsions as a novel delivery system for lipophilic materials, such as essential oils, flavors, and fragrances is one of the growing technologies used in cosmetic, pharmaceutical, and food industries. Their characteristic properties, like small droplet size with high interfacial area, transparent or semi-transparent appearance, low viscosity, and high kinetic stability, make them a perfect vehicle for fragrances, in the perfume industry. They could be a great alternative to water-based perfumes, without alcohol, and solve problems related to the oxidation and low bioavailability of fragrances with other non-alcoholic vehicles of perfumes like pomades or gels. The aim of our study was to develop stable Oil-in-Water (O/W) nanoemulsions that are compatible with selected fragrance compositions, without ethanol, polyols, and ionic surfactants, and to study their physicochemical, microbiological, and dermatological properties. The nano-perfume systems were obtained with a low-energy (Phase Inversion Composition; PIC) and with a high-energy (ultrasound, US) method, taking into account the possibility of moving from the laboratory scale to an industrial scale. The optimized nano-perfume formulations, prepared with different methods, yielded the same physicochemical properties (stability, medium droplet size of the inner phase, polydispersity, viscosity, surface tension, pH, density). Stable systems were obtained with a fragrance composition concentration within 6–15% range. These formulations had a low viscosity and a pH suitable for the skin. Moreover, the obtained results confirmed the protective role of nanoemulsions. The peroxide number measurement (POV) showed that the tested fragrance compositions had a high chemical stability. The results of the microbiological tests confirmed that the obtained products were free of microbiological contamination and were appropriately preserved. The dermatological test results confirmed the safety of the developed preparations.

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