▎ 摘　　要

NOVELTY - The method for preparing thymine-modified graphene quantum dots, involves (i) dissolving carbon fiber in strong acid solution, stirring, ultrasonically dispersing to obtain mixture of carbon fiber and strong acid ultrasonic solution, (ii) heating and refluxing to obtain solution (A), (iii) mixing solution (A) with secondary water, adding carbonate, adjusting pH of solution, filtering, and dialyzing to obtain graphene quantum dot solution, (iv) adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS), activating, adding ethylenediamine and reacting. USE - Method for preparing thymine-modified graphene quantum dots used for detecting mercury ion concentration in water, medicine or food (all claimed). ADVANTAGE - The raw materials used in the preparation are readily available. The thymine-modified graphene quantum dots can monitor mercury ions with high sensitivity and high selectivity in real-time. DETAILED DESCRIPTION - The method for preparing thymine-modified graphene quantum dots, involves (i) dissolving carbon fiber in a strong acid solution, evenly stirring, ultrasonically dispersing to obtain mixture of carbon fiber and strong acid ultrasonic solution, (ii) heating the ultrasonic solution of carbon fiber and strong acid and refluxing to obtain solution (A), (iii) mixing the solution (A) with secondary water, adding carbonate, and adjusting the pH of the conditioning solution to 7-9, filtering, and performing dialysis to obtain graphene quantum dot solution, (iv) adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to the graphene quantum dot solution, performing activation, adding ethylenediamine, reacting for 4-8 hours, and performing dialysis to prepare graphene quantum dots solution covalently modified with ethylenediamine, (v) taking appropriate amount of thymine-1-acetic acid, dissolving in inorganic solvent, adding EDC and NHS, activating, and then adding graphene quantum dots solution covalently modified with ethylenediamine obtained in step (iv), reacting for 4-8 hours and performing dialysis to obtain thymine-modified graphene quantum dots.