▎ 摘　　要

NOVELTY - BL-CQDs (banyan leaves-carbon quantum dots) fluorescent probe comprises taking ficus microcarpa leaves as a raw material, and obtaining carbon quantum dots (BL-CQDs) through extraction and carbonization reactions, where the lattice spacing of the obtained BL-CQDs is 0.209 nm, and the carbon quantum dots have a graphene-like structure, the microscopic morphology of the particles is monodispersed and uniformly distributed in a spherical manner, and the average size of BL-CQDs particles is 1.6-1.8 nm, the surface of the material contains hydrophilic functional groups of hydroxyl, carbonyl and aldehyde, meanwhile, BL-CQDs have the characteristics of single excitation and double emission fluorescence, and the probe is the BL-CQDs fluorescent probe. USE - Banyan leaves-carbon quantum dots fluorescent probe for use in angiotensin converting enzyme (ACE) activity detection method, ACEI screening method and angiotensin converting enzyme inhibitor (claimed). ADVANTAGE - The BL-CQDs fluorescent probe has optical characteristics, photobleaching resistance, pH stability, salt stability and interference resistance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: a method for preparing BL-CQDs fluorescent probe, which involves: i. processing raw materials, namely, taking fresh Ficus microcarpa leaves as raw materials, cleaning and crushing the ficus microcarpa leaves, and extracting under certain conditions to obtain extract liquor; and ii. preparing carbon quantum dots, namely performing solvothermal carbonization on the extract liquid obtained in the step 1 under a certain condition, filtering after the reaction is finished, and filtering the filtrate through an ultrafiltration membrane to obtain a carbon quantum dot solution, wherein the obtained carbon quantum dot solution is referred to as BL-CQDs for short, namely the BL-CQDs fluorescent probe; an application of an angiotensin converting enzyme (ACE) activity detection method based on a BL-CQDs fluorescent probe, which involves: a. establishing an enzymatic reaction system of a standard angiotensin converting enzyme ACE solution, namely mixing a boric acid-sodium borate buffer (BBS) and a equoyl-histidyl-leucine (HHL) to obtain a mixed solution, then adding ACE into the mixed solution, and uniformly mixing to obtain the enzymatic reaction system of the standard ACE solution; b. establishing an enzyme inactivation reaction system, namely performing water bath incubation on the enzyme inactivation reaction system obtained in the step a under certain conditions, and adding hydrogen chloride (HCl) to terminate the reaction after the water bath is finished, so as to obtain the enzyme inactivation reaction system; and c. testing the fluorescence intensity of the enzyme inactivation reaction system, adding BL-CQDs into the enzyme inactivation reaction system obtained in the step b by taking BL-CQDs and HHL meeting a certain volume ratio, and testing the fluorescence intensity under a certain condition to obtain the concentration data of the product HA of the enzymatic reaction, namely realizing the ACE activity detection; an application of an angiotensin converting enzyme inhibitor (ACEI) screening method based on BL-CQDs fluorescent probes, which involves screening the ACEI through an ACE activity inhibition experiment, wherein the specific method of the ACE activity inhibition experiment comprises the steps of adding an inhibitor into a standard ACE solution enzymatic reaction system during the step b, carrying out enzymatic reaction, and then testing the fluorescence intensity in the subsequent step c to obtain the effect of the inhibitor; and an angiotensin converting enzyme inhibitor, which is yellow leaf extract, and the inhibition rate of 2.5 mg of the yellow tabebuia avellanedae leaf extract on ACE of 0.5U/L is 88.20%.Tabebuia avellanedae