A process comprises (a) combining (1) at least one metal cation source, (2) at least one phosphate anion source, (3) at least one organic base comprising at least one organic moiety comprising at least about five carbon atoms, and (4) at least one organosilane comprising at least one organic moiety comprising at least about six carbon atoms; and (b) allowing the metal cation source and the phosphate anion source to react in the presence of the organic base and the organosilane (for example, to form surface-modified metal phosphate nanoparticles).