A reduction in the size of nanoparticles and PI in this study maybe as a result of the higher interfacial tension between nanoparticles and the aqueous phase which leads to a more homogenized nanoparticles in the aqueous phase. The phenomenon for zeta potential can be explained by the fact that oleic acid has negatively charged carboxylic groups. NLC revealed the highest zeta potential values, possibly due to the accumulation of oleic acid at the surface of the nanoparticles [20