▎ 摘　　要

In this study, a microRNA (miRNA) biosensor based on fluorescence quenching technique is designed and developed to determine the miRNAs with altered expression during nitrogen deficiency in plants. The method is based on the difference between the fluorescence absorption of graphene oxide (GO) nanosheets in the present of gold nanoparticles-labelled DNA probe and that of GO after the DNA hybridization with target miRNA. Results revealed that the biosensor was capable of determining the concentration of 17 miRNAs related to the nitrogen stress in plants with acceptable specificity, limit of detection (LoD) and linear range. LoD values for the determination of studied miRNAs ranged from 45 to 420 aM. Furthermore, wide linear ranges were obtained for the determination of miRNA-156 (500-100,000 aM), miRNA-167 (500-20,000 aM), miRNA-171 (200-80,000 aM), and miRNA-398 (300-120,000 aM). The introduced biosensor can be a more reliable alternative to polymerase chain reaction (PCR) and northern blot for plant scientists who work on plant stress-related miRNAs.