Removing an asphaltene particle from a substrate includes contacting a silicate nanoparticle with a chemical group to form a functionalized silicate nanoparticle, the chemical group includes a first portion; and a second portion comprising an aromatic moiety, the first portion being bonded to the silicate nanoparticle; contacting the asphaltene particle with the functionalized silicate nanoparticle, the asphaltene particle being disposed on the substrate; interposing the functionalized silicate nanoparticle between the asphaltene particle and the substrate; and separating the asphaltene particle from the substrate with the functionalized silicate nanoparticle to remove the asphaltene particle. A composition includes a functionalized silicate nanoparticle comprising a reaction product of a silicate nanoparticle and an aromatic compound; and a fluid. The aromatic compound includes a chemical group that includes a first portion, the first portion being directly bonded to the silicate nanoparticle in the functionalized silicate nanoparticle; and a second portion including an aromatic moiety.