In various aspects provided are methods for producing a nanoparticle within a cross-linked, collapsed polymeric material. In various embodiments, the methods comprise (a) providing a shape-static polymer template with a size in the range between about 1 nm to about 100 nm; (b)) incorporating one or more nanoparticle precursor moieties with the shape-static polymer template; and either (c) oxidizing the precursor moieties to form a composite nanoparticle comprising one or more of an inorganic oxide and hydroxide nanoparticle; or (c) adding an ion with an opposite charge polarity to the at least one nanoparticle precursor moieties to effect formation of a composite nanoparticle.