Smart engineering of a self-powered and integrated nanocomposite for intracellular MicroRNA imaging

Abstract

Over the past 2 years, many DNA motors have been synthesized and run in living cells, but there are still challenges in designing integrated DNA motors self-powered to enable autonomous intracellular walking without auxiliary additives. Herein, we report a smart strategy based on a DNA motor–MnO2 nanocomposite, which successfully meets these requirements of intracellular analysis and enables sensitive imaging of specific microRNAs (miRNAs) in living cells. Once the motor system enters the cells, MnO2 nanosheets are reduced by intracellular glutathione (GSH), which not only releases the DNA motors that can be activated by the intracellular target miRNA via binding-induced DNA assembly, but also produces cofactors, Mn2+, that can be used as fuels for autonomous and progressive walking. In addition, the false-positive signal generated by GSH on the DNA motor destruction can be greatly reduced due to the consumption of GSH during this process. This strategy not only combines the advantages of previous dynamic nanomachines based on Au nanoparticles but also has merits of higher integration, lower background fluorescence, and self-powered performance, which provide an efficient avenue for visualizing various biomolecules in living cells.