Dual-microRNA-controlled double-amplified cascaded logic DNA circuits for accurate discrimination of cell subtypes.

Accurate discrimination between different cells at the molecular level is particularly important for disease diagnosis. Endogenous RNAs are such molecular candidates for cancer cell subtype identification. But the key is that there is often low abundance of RNAs in live cells, or some RNAs are often shared by multiple types of cells. Thus, we have designed dual-microRNA-controlled double-amplified cascaded logic DNA circuits for cancer cell subtype identification. The basic idea is to improve sensitivity by cascading DNAzyme and hybridization chain reaction (HCR), and improve accuracy by simultaneous detection of miR-122 and miR-21. The in-tube and in-cell experimental results show that the cascaded logic DNA circuits can work and serve to differentiate the liver cancer cells Huh7 from other normal cells and cancer cells. We anticipate that this design can be widely applied in facilitating basic biomedical research and accurate disease diagnosis.

A DNA nanowire based localized catalytic hairpin assembly reaction for microRNA imaging in live cells.

Here, we have developed a localized catalytic hairpin assembly (LCHA) strategy for intracellular miR-21 imaging by using DNA nanowires confining both hairpin probes in a compact space. The LCHA is constructed by interval hybridization of DNA hairpin probe pairs to a DNA nanowire with multiplex footholds generated by alternating chain hybridization. Compared to the conventional catalytic hairpin assembly (CHA) strategy, the LCHA significantly shortens the reaction time and enhances the sensitivity. Moreover, the proposed LCHA can serve as a carrier for delivery of probes into live cells as well as protect the probes from nuclease degradation and enhances the stability. We anticipate that this design can be widely applied in facilitating basic biomedical research and disease diagnosis.

Hairpin-fuelled catalytic nanobeacons for amplified microRNA imaging in live cells.

Direct imaging of low-abundance RNAs in live cells remains challenging because of the relatively low sensitivity of conventional molecular imaging probes. Here, we introduce hairpin-fuelled catalytic nanobeacons for microRNA (miRNA) imaging in live cells with signal amplification capacity. Compared with the conventional nanobeacons in solution, the catalytic nanobeacons could generate two orders of magnitude higher sensitivity.