▎ 摘　　要

NOVELTY - Method (A) for preparing graphene oxide involves (a) mixing graphite powder, potassium nitrate and concentrated sulfuric acid to obtain system (1), (b) mixing potassium permanganate, potassium nitrate and concentrated sulfuric acid to obtain system (2), (c) adding system (2) to system (1) to react to obtain a reaction solution containing manganese-intercalated graphite, (d) precipitating the manganese-intercalated graphite, removing supernatant, and adding water in the obtained manganese-intercalated graphite, (e) adding hydrogen peroxide and stirring to obtain a graphene oxide stock solution, and (f) dialyzing the prepared graphene stock solution to obtain graphene oxide. USE - The method (A) is useful for preparing graphene oxide, which is useful for performing RT-qPCR for detecting circulating microRNA, and in reagent for preparing kit for evaluating effect of neoadjuvant chemotherapy for breast cancer. The microRNA is microRNA-21, microRNA-155 and/or microRNA-195 (all claimed). ADVANTAGE - The method (A) prepares graphene oxide, which realizes non-invasive and high-sensitivity qRT-PCR detection of expression level of circulating microRNAs, ensures early prediction of neoadjuvant chemotherapy response in breast cancer patients, and reduces detection limit of detecting microRNAs by 10 times. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: a graphene oxide being prepared by the above-mentioned method (A); use of the graphene oxide for performing quantitative reverse transcription PCR (RT-qPCR) to detect circulating microRNA, where the microRNA is microRNA-21, microRNA-155 and/or microRNA-195, preferably (i) when the microRNA is microRNA-21, and primers have base pair sequences of SEQ ID NOs: 1 and 2, (ii) when the microRNA is microRNA-155, and primers have base pair sequences of SEQ ID NOs: 3 and 4, and (iii) when the microRNA is microRNA-195, and primers have base pair sequences of SEQ ID NOs: 5 and 6; a method for performing qRT-PCR detection of circulating microRNA involves (a) hatching the graphene oxide together with primer in a mass ratio of 1-6:1, preferably 4:1, diluting the graphene oxide with water to a concentration of 4.77-32.52 μg/ml, preferably 7.86 μg/ml, and incubating at 15-35°C, preferably 25°C for 30±5 minutes, preferably 30 minutes, where the primer comprises forward primer and reaction primer in molar ratio of 1:1, and (b) preparing qRT-PCR reaction system for real-time fluorescent quantitative PCR; and use of a reagent for detecting microRNA in preparation of a kit for evaluating effect of neoadjuvant chemotherapy for breast cancer, where the reagent for detecting microRNA is a qRT-PCR test reagent comprising the graphene oxide and the primers, and the qRT-PCR detection is performed after the graphene oxide is incubated with primers. gcgcaacaccagtcgatg (SEQ ID NO: 1), agtgcagggtccgaggtatt (SEQ ID NO: 2), cgcgttaatgctaatcgtgata (SEQ ID NO: 3), agtgcagggtccgaggtatt (SEQ ID NO: 4), gcgcgtagcagcacagaaat (SEQ ID NO: 5) and agtgcagggtccgaggtatt (SEQ ID NO: 6).