Multivalent self-assembled nano string lights for tumor-targeted delivery and accelerated biomarker imaging in living cells and in vivo

Highly efficient monitoring of microRNA is of great significance for cancer research. By attaching aptamers to DNA nanowires through base pairing, here we designed a multivalent self-assembled DNA nanowire for fast quantification of intracellular target miRNAs in special cancer cells. In this work, an aptamer AS1411 and a microRNA-21 anti-sequence labeled with Cy5 were fixed on DNA nanowires, and then a short DNA strand with black hole quencher 2 (BHQ2) hybridizes with the microRNA-21 anti-sequence to quench Cy5. With the aid of AS1411, the probe can recognize and enter the target special cells efficiently. In addition, because of the banding between microRNA-21 and microRNA-21 anti-sequence, short DNA strands with BHQ2 are detached from the DNA nanowire and result in the recovery of Cy5 fluorescence signals. Ultimately, the fluorescence of Cy5 was activated quickly due to the high local concentration of recognition units on the nanowire, resulting in a large number of activated Cy5 dyes in a short time just like DNA nano string lights. Experimental results revealed that the designed DNA nanowire probe shows great performance for specifically and quickly monitoring microRNA-21 in living cells and in vivo. This developed strategy may become a general platform for detecting targets in living cells and possess great potential for biological and diagnostic research.