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 homog- enized nanoparticles in the aqueous phase. The phenomenon for zeta potential can be explained by the fact that oleic acid has neg- atively 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