▎ 摘　　要

NOVELTY - Water-soluble graphene quantum dots comprise a macromolecular polymer, such as polyethyleneimine, are obtained by hydrothermal treatment and self-curled into a fluorescent ring, and have a diameter of 4 nm, UV absorption at 350 nm, fluorescence in visible blue light region, and a surface with large number of amino groups. USE - Water-soluble graphene quantum dots are used for detecting epinephrine at lowest detection range, for quantitative detection of dopamine in body fluid, and for detecting heavy metals in water (all claimed). ADVANTAGE - The water-soluble graphene quantum dots use a nontoxic polymer, have excellent fluorescence, can be prepared by a simple method using economical raw materials with excellent repeatability with low equipment requirement, and are safe and nontoxic. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of water-soluble graphene quantum dots, which involves dissolving 0.0008-0.564 g polyethyleneimine at room temperature in 0-12 mL water, stirring for complete dissolution, introducing nitrogen through the solution for 15 minutes to remove dissolved oxygen, transferring to a reactor, heating for 7-48 hours at 180 degrees C, and obtaining particles of size 4-5 nm.