Endogenous enzyme-activated AND-gate DNA nanomachines for intracellular miRNA detection and cell-selective imaging.

The occurrence and development of tumors are accompanied by the abnormal expression of specific microRNAs (miRNAs). Therefore, miRNAs are considered as an important biomarker. The establishment of efficient, simple and sensitive miRNA imaging methods in living cells will contribute to the early diagnosis, treatment and drug development of diseases. In this study, we developed an endogenous enzyme-initiated AND logic circuit using gold nanocubes (AuNCs) as carriers for simultaneous detection of miRNA-21 and miRNA-210 in cells. Apurinic/apyrimidinic endonuclease 1 (APE1) and telomerase (TE), which are overexpressed in cancer cells, act as control switches in a logic circuit that enables sensitive in situ analysis of intracellular miRNAs without additional external intervention. At the same time, due to the lack of necessary enzymes as activation switches, the DNA circuit in normal cells remains in an inactive state. This strategy effectively reduces the risk of false positive signal generation. Our research results show that the logic circuit can not only distinguish between cancer cells and normal cells, and able to distinguish between different types of cancer cells. This finding provides a promising approach to accurately identify cell types.