Regulation of the lyophilicity and lyophobicity of a particle is very important for controlling interparticle interactions in solution. Through these interactions, we can precisely tune the formation of regular nanoparticle arrays and superlattices to create new materials. We demonstrate methods of controlling interparticle interactions that are effective for the formation of high-quality nanoparticle crystals. Unexpected electronic properties in high-quality superlattices were observed.