The development of nanoparticles has seen great progress in recent years in the field of medicine, focusing on targeted delivery of drugs and vaccines. In order to achieve greater vaccine efficacy and provide long-term protection against pathogens, adjuvants are added to vaccines, with aluminum salts and pattern-recognition receptor agonists, being the most commonly used nowadays. Various nanodelivery systems have been developed for adjuvant delivery, among which lipid nanoparticles show great promise as they allow targeted delivery and improved stability of incorporated active ingredients in vivo.
The aim of this master's thesis was to produce physically stable dispersion of lipid nanoparticles (solid lipid nanoparticles and nanostructured lipid carriers) with incorporated adjuvant SG11 by sonication of melted lipid into aqueous solution of stabilizers. We optimized the conditions for the production of lipid nanoparticles with the goal of producing nanoparticles with an average size < 200 nm and a narrow particle size distribution. The dispersions were characterized by measuring the average particle diameter, polydispersity index and zeta potential. These properties were monitored for up to 60 days after production to assess the physical stability of nanoparticles and stored under different storage conditions. Different media (purified water, phosphate buffer) and organic solvents (ethanol, tetrahydrofuran) were used to produce vaccine adjuvant loaded nanoparticles, which were stored under different conditions (in refrigerator, in freezer).
Nanoparticles stored in the refrigerator were found to be more physically stable than those stored in the freezer. High-performance liquid chromatography was used to determine the adjuvant content in the lipid nanoparticle dispersion. The results confirmed the efficient incorporation of the adjuvant into the lipid nanoparticles. Based on measurements of adjuvant content in nanoparticles after 60 days from production, we found that in some samples, there was a »leakage« of the adjuvant from the particles. Ethanol proved to be a better solvent for adjuvant incorporation into nanoparticles compared to tetrahydrofuran. By using phosphate buffer as a dispersion medium, we aimed to prepare nanoparticle dispersions, biocompatible with cells. The results showed that nanoparticle dispersion was physically more stable when a solution of stabilizers in phosphate buffer was used for its production and redispersion of nanoparticles compared to phosphate buffer used alone.
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