Size-selective hybridization chain reaction for accurate signal amplification in living cancer cells

Abstract

Accurate signal amplification in living cells is highly important in biomedical research and medical diagnostics. Benefiting from its enzyme-free, efficient isothermal signal amplification ability, hybridization chain reaction (HCR) plays an important role in intracellular signal amplification; however, HCR fails the accurate signal amplification in the situation when the properties of some biological targets and analogues are too similar. Particularly, their signal amplification accuracy for mature miRNAs is unsatisfactory due to the signal interference of precursor microRNAs (abbreviated as pre-miRNAs), which also contain the sequence of mature miRNAs. Herein, we develop the first example of size-selective hybridization chain reaction probe for accurate signal amplification, which achieved accurate and sensitive biosensing of mature miRNAs in living cancer cells. Our probe, termed as qTcage, consists of a DNA nanocage for size-selective responsive to mature miRNAs, as well as a quadrivalent tetrahedral DNA structure for HCR signal amplification. Benefiting from the size-selectivity of DNA nanocage, shorter mature miRNAs (19–23 nt) rather than longer pre-miRNAs (60–70 nt) could enter the cavity to release triggers strand, which activates HCR reaction for fluorescence signal recovery. The probe efficiently reduces signal interference of pre-miRNAs and improves the imaging sensitivity for intracellular mature miRNAs, which was successfully applied for mature miRNAs imaging during drug treatment. Overall, this strategy provides the hybridization chain reaction with the feature of size-selective ability, which holds promise for further accurate signal amplification in biological processes study and clinical diagnostics.