Dear Divya Jayoti ,

The functionalization of a solid particle relies basically on the ability of the surface of the particle and the chemical you are aiming to functionalize with, to react together, with the aim of bonding, in your case, the oleic acid to the colloid. The way of doing it will depend specifically on that basically: on the chemistry that will be involved to link the acid to the surface of the particle. Since the oleic acid is exactly that, an acid, a way would be to explore a little bit the chemistry of the acid groups (how do they react, what other groups are needed, etc.). Also, knowing a bit more about the surface chemical groups of your particles would also be beneficial.

This article might be insightful for your needs:

Article Oleic-acid functionalized mesoporous silica nanoparticles wi...

Hope it helps!