Self-assembly of gold nanoparticles on a single crystalline sapphire substrate

► Functionalization of the surface of single crystalline sapphire substrate. ► Hot hydrogen peroxide makes the surface contact angle of the sapphire substrate smaller according to OH groups on the surface. ► Silan coupling reagent can be attached to the hydrophilic sapphire substrate surface. ► Negatively charged gold nanoparticles could be immobilized on the cationic sapphire substrate surface.