8-Mercaptooctanoic acid (MOA) is an carboxylic acid terminated alkanethiol that forms self-assembled monolayers (SAMs) that facilitate subsequent surface immobilization of other molecular species. 8-mercaptooctanoic acid (MOA) forms a self-assembled monolayer (SAM) on the surface of nanoparticles. MOA consists of thiol and carboxylic groups which helps in the surface treatment of different nanoparticles.