▎ 摘　　要

NOVELTY - Preparing a bifunctional graphene quantum dot involves using citric acid, histidine, D-penicillamine in the molar ratio of 1:0.1:0.01-1:1:1. A bifunctional graphene quantum dot DPA-GQD-His is prepared by a hydrothermal method. USE - Method for preparing bifunctional graphene quantum dot. ADVANTAGE - The method enables to prepare bifunctional graphene quantum dot, which are capable of quantitatively detecting single or multiple organophosphorus pesticides with high sensitivity and high selectivity, and the preparation method is simple and easy to popularize. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a biometric sensor, which comprises the bifunctional graphene quantum dot; and (2) a method for quantitatively detecting acetamiprid, which involves dissolving DPA-GQD-His in a phosphate buffer solution of pH 6.5-7.4, where the mass concentration of DPA-GQD-His is 0.01-1 mg/mL; taking 10-100 microL of 0.1-10 microM DNA sequence (SEQ ID NO: 1) and 10-100 microL of 0.1-10 microM DNA sequence (SEQ ID NO: 2) and mixing in 100-300 microL PBS buffer solution, and incubating at room temperature for 20-60 minutes; adding acetamiprid of different concentration to the mixed solution, and placing at 20-30 degrees C for 20-40 minutes after shaking; adding 10-50 microL of 25-50 mM KCl to the above solution; adding 25-100 microL of 0.5-10 microM chloromethemoglobin hemin, shaking and shaking at 35-40 degrees C for 40-80 minutes; adding 50-120 microL of 50-100mM H2O2, 50-100 microL of 40-140 mM o-phenylenediamine OPD, and 50-200 microL of 0.01-1 mg/mLDPA-GQD-His in phosphate buffered saline solution and incubating at 35-40 degrees C after 40-80 minutes, scanning the fluorescence spectrum, where the excitation wavelengths are 360nm and 420nm, and the slit width is 5-10nm, where quantitative detection of acetamiprid using changes in fluorescence intensity.