A luminescent nanocomposite comprising functionalized graphene and a luminescent moiety, its fabrication, and uses are described. The luminescent moiety is anchored non-covalently to the functionalized graphene. Luminescence properties of the nanocomposite may be modulated by choosing appropriate luminescent moieties such as native lactoferrin, native lactoferrin protected gold clusters, and so forth. Mechanical properties of the nanocomposite may be modulated by adding a biopolymer such as Chitosan. The nanocomposite may be used as a luminescent ink for encoding information, or a luminescent film for tagging articles of manufacture such as electronic waste components.