▎ 摘　　要

NOVELTY - Preparing graphene-rare earth composite material comprises e.g. (1) weighing citric acid, histidine, ethylenediamine, and folic acid, mixing, adding deionized water, ultrasonic dissolving to obtain reaction solution, placing the reaction solution in an oven, reacting in oven, directly obtaining histidine quantum dot solid product, preparing histidine quantum dot solid product into aqueous solution; (2) mixing yttrium(III) chloride solution, ytterbium(III) chloride solution, and erbium(III) chloride solution, adding histidine quantum dot aqueous solution obtained in step (1), and stirring at room temperature for half hour; (3) dropwise adding sodium fluoride solution to the solution obtained in step (2) under stirring, and stirring for one hour at room temperature; and (4) transferring the solution obtained in step (3) to polytetrafluoroethylene high-pressure reactor, heating in oven for reaction, reaction temperature is 150-300 degrees C, and the reaction time is 1-10 hours. USE - The composite material is useful for detecting the residual concentration of carbendazim, and combined toxicity effect of benzimidazole pesticide residues (all claimed). ADVANTAGE - The composite material: has good biocompatibility, high safety, high sensitivity of detection. DETAILED DESCRIPTION - Preparing graphene-rare earth composite material comprises (1) weighing citric acid, histidine, ethylenediamine, and folic acid, mixing, adding deionized water, ultrasonic dissolving to obtain reaction solution, placing the reaction solution in an oven, reacting for 0.5-10 hours in oven at 150-250 degrees C, directly obtaining histidine quantum dot solid product, preparing histidine quantum dot solid product into aqueous solution of 25-200 mg/ml; (2) mixing 5-50 mu l yttrium(III) chloride solution (0.01-1 mol/l), 5-50 mu l ytterbium(III) chloride solution (0.01-1 mol/l), and 5-50 mu l erbium(III) chloride solution (0.01-1 mol/l), adding 0.1-10 ml histidine quantum dot aqueous solution obtained in step (1), and stirring at room temperature for half hour; (3) dropwise adding 1-10 ml sodium fluoride solution (0.01-1 mol/l) to the solution obtained in step (2) under stirring, and stirring for one hour at room temperature; (4) transferring the solution obtained in step (3) to polytetrafluoroethylene high-pressure reactor, heating in oven for reaction, reaction temperature is 150-300 degrees C, and the reaction time is 1-10 hours, and (5) naturally cooling the solution in the reaction kettle to room temperature, taking out, adding into beaker, allowing to stand for 12 hours, taking the supernatant for centrifuging and washing for many times, and freeze-drying to obtain solid graphene quantum dot-rare earth composite nano-materials. INDEPENDENT CLAIMS are also included for: (1) use of graphene-rare earth composite material for detecting the residual concentration of carbendazim (a) connecting graphene quantum dot-rare earth composite upconversion nanomaterials to hairpin DNA with gold nanometers via EDC/NHS, where hairpin DNA-linked gold nanoparticles quench the fluorescence emission of graphene quantum dot-rare earth composite upconversion nanomaterials, (b) adding carbendazim aptamer, complementary pairing carbendazim aptamer with hairpin DNA bases to emit graphene quantum dot-rare earth composite upconversion nanomaterial fluorescence, and (c) introducing carbendazim with the increase of carbendazim concentration, fluorescence quenching of graphene quantum dot-rare earth composite up-conversion nanomaterials, according to the linear relationship between carbendazim concentration and fluorescence quenching, and detecting residual carbendazim concentration, where the graphene-rare earth composite material is graphene quantum dot-rare earth composite up-conversion nano material prepared by above mentioned method; and (2) use of graphene-rare earth composite material to combined toxicity effect of benzimidazole pesticide residues comprising (i) culturing Hep G2 liver cancer cell strain by: culturing MEM medium containing 10(vol.%/vol.%) fetal bovine serum in 37 degrees C, 5% CO2 saturated humidity constant temperature cell incubator, (ii) cancelling the Hep G2 cell suspension diluted with complete culture medium, adjusting the density to 3.5x 105 cells/ml, inoculating 100 mu l/well in 96-well transparent cell culture plate in 5% CO2, and incubating for 24 hours at 37 degrees C, (iii) adding 90 mu l fresh serum-free culture medium to the blank cell culture plate as the zeroing group, absorbing the culture medium in step (ii), adding 90 mu l fresh serum-free medium as control group, absorbing the culture medium in step (2), adding 90 mu l fresh serum-free medium and 10 mu l two benzimidazole pesticides at different concentrations in ratio of 1:1 as treatment groups, incubating the zeroing group, the control group and the treatment group in 5% carbon dioxide, incubating for 24 hours at 37 degrees C in constant temperature cell incubator, (iv) removing the medium of zeroing group, the control group and the treatment group, adding 100 mu l graphene quantum dot-rare earth composite upconversion nanomaterial solution to each well, and incubating for 3.5 hours at 5% carbon dioxide and 37 degrees C, (v) continuously adding the phosphate buffered saline solution to the zeroing group, the control group and the treatment group, placing them on a shaker to shake, so that the cells on the cell culture plate are dispersed in the solution as much as possible, (vi) centrifugal washing the solution obtained by dispersing the zeroing group, the control group and the treatment group, removing the graphene quantum dot-rare earth composite up-conversion nanomaterials that have not been treated in the treatment group, and using fluorescence spectrometer to detect the fluorescence emission intensity at 541 nm under 980 nm excitation, (vii) removing the non-functioning graphene quantum dot-rare earth composite upconversion nanomaterials from the zeroing group and the control group, and measuring the fluorescence emission intensity at 541 nm of the zero adjustment group and the control group, and (viii) according to: cell survival rate = (fluorescence intensity of the treatment group-fluorescence intensity of the zeroing group)/(fluorescence intensity of the control group-fluorescence intensity of the zeroing group)x 100%, establishing linear regression equation based on the pesticide concentration and cell survival rate, and calculating cell LC50 based on the established linear regression equation.