Using a DLS method to approximate the dimensions of solid triglyceride nanoparticles

An approach in the use of lipid nanoparticles involves their adaptation for the formulation of hydrophilic compounds, such as therapeutic biomacromolecules (e.g., nucleic acids, proteins). Due to the characteristics of these molecules, it is not favorable for them to be incorporated in the lipid core of the nanoparticles. An alternative option may be their adsorption on the particle surface. Lipid nanoparticles, due to their size in the nanometer range, offer a high specific surface area for drug loading. In addition, their possible anisometric shape could enhance the capacity for hydrophilic drug adsorption. Thus, optimizing the particle size and modifying the particle anisometry might be a viable strategy to increase the specific surface area of the dispersed system. The aim of this study was to evaluate the possible influence of triglyceride type as well as particle size, varied through the modification of manufacturing parameters such as emulsifier concentration and the number of homogenization cycles, on particle anisometry. To achieve this, poloxamer-stabilized solid triglyceride nanoparticles were prepared by means of microfluidic high-pressure homogenization. The aspect ratio of the nanoparticles, as well as its potential correlation with triglyceride type, particle size and emulsifier concentration, along with the aspect ratio change due to autoclaving, were investigated. These investigations were conducted using a DLS method [1] based on a modified version of a hydrodynamic model introduced by Perrin [2, 3]. The results provide a rough estimate of the evolution of the aspect ratio in relation to the modified production parameters. It was observed that as the triglyceride chain length increased from trilaurin to tristearin, the anisometry of the particles also increased. After autoclaving, the order of the aspect ratios of the triglycerides remained unchanged. The aspect ratios of the autoclaved samples were, however, larger than those of the non-autoclaved versions. With regard to the emulsifier effect and particle size, it was observed that an increase in poloxamer concentration and a reduction in particle size resulted in a reduction in the anisometry of the particles.