▎ 摘　　要

Since microRNA-21 (miR-21) and protein programmed cell death 4 (PDCD4) are implicated in tumor progression, simultaneous monitoring of the dynamic variation of miR-21 and PDCD4 mRNA in living cells is of great interest for understanding their relationship in the pathology of the disease. Herein, a versatile nanoprobe based on graphene oxide (GO) and DNA was prepared which can simultaneously monitor and visualize miR-21 and PDCD4 mRNA in living cells. In vitro experiments demonstrate that the nanoprobe exhibits outstanding selectivity and high sensitivity towards miR-21 and PDCD4 mRNA. Moreover, by exploiting the DNA/GO sensing platform, simultaneous imaging of miR-21 and PDCD4 mRNA in MCF-7 human breast cancer cells has been realized. More significantly, an inverse correlation between miR-21 and PDCD4 mRNA was verified by fluorescence confocal imaging and RT-PCR results, indicating the distinguishing ability of the nanoprobe at various expression levels of RNAs. The current strategy provides a promising tool to implement the detection of miR-21 and PDCD4 mRNA in cancer cells and can be expected to be applied for other biomolecular sensing.