EVALUATION OF THE ROLE OF INSTRUMENTAL PARAMETERS DURING THE PREPARATION OF SLN BY ULTRASONIC METHOD

Ultrasonic method (US) is a ‘cheap and fast’ dispersing technique widely used to prepare lipid nanoparticles characterized by high homogeneity and reduced particle sizes. US method provides an initial step represented by the formation of a precursor oil-in-water ‘nanoemulsion’ followed by subsequent solidification (cooling step) of the dispersed lipid phase. High shear homogenization and ultrasonication are techniques involved, at different times, during this preparation method. The first objective of the study has been the optimization of the instrumental parameters using as evaluation indexes the polidispersity index (PDI), the particle size and the drug loading capacity of solid lipid nanoparticles finally obtained. Response surface method (RSM) was used to assess optimal preparation parameters such as high shear homogenization time, ultrasound time and stirring time during the cooling step. During the second phase of the work, the importance of instrumental parameters has been evaluated varying the type of solid lipid used to prepare solid lipid nanoparticles. The response surfaces (RS), generated by varying time over the categorical factors, pointed out a high influence of the numerical factor levels on particle size and polydispersity index.In particular high shear homogenization time had a noticeable effect on PDI if compared to ultrasound time, as coming from the RS curvature observation. Moreover, both dispersing methods play a main role in obtaining a reduced size, even though long treatment times seem did not produce a further reduction of nanoparticle dimensions. The use of a different solid lipid to prepare the nanoparticles did not produce a significant modification of RS curvature, thus confirming the results previously observed.