Two-color imaging of microRNA with enzyme-free signal amplification via hybridization chain reactions in living cells

In situ imaging of miRNA in living cells could facilitate the monitoring of the dynamic expression and distribution of miRNA and research on miRNA-related cellular processes and diseases. Given the low expression levels and even down-regulation of cellular miRNA that is associated with some diseases, amplification strategies are imperative for intracellular miRNA imaging. The present paper proposes a non-destructive amplification strategy for use in living cells. This amplification strategy utilizes the enzyme-free hybridization chain reaction (HCR) with graphene oxide (GO) as a carrier to image cellular miRNA. The resulting signal amplification provides excellent recognition and signal enhancement of specific miRNAs in living cells. As the fluorescence quencher and probe carrier, GO enables activation of the signal switch and effective intracellular delivery of amplification reagents. This new imaging method realizes simple, sensitive and non-destructive signal amplification of miRNA in living cells and has an ability to simultaneously image two types of miRNA in the same cell. This method supplies accurate information regarding cellular miRNA-related biological events and provides a new tool for highly sensitive and simultaneous imaging of multiple low-level biomarkers, thereby improving the accuracy of early disease diagnosis.