Specific and Direct Amplified Detection of MicroRNA with MicroRNA:Argonaute-2 Cleavage (miRACle) Beacons

Enzyme Translocation-Mediated Signal Amplification for Spatially Selective Aptasensing of ATP in Inflammatory Cells

Amplified ATP imaging in inflammatory cells is highly desirable. However, the spatial selectivity of current amplification methods is limited, that is, signal amplification is performed systemically and not in a disease site-specific manner. Here we present a versatile strategy, termed enzymatically triggerable, aptamer-based signal amplification (ETA-SA), that enables inflammatory cell-specific imaging of ATP through spatially-resolved signal amplification. The ETA-SA leverages a translocated enzyme in inflammatory cells to activate DNA aptamer probes and further drive cascade reactions through the consumption of hairpin fuels, which, however, exerts no ATP response activity in normal cells, leading to a significantly improved sensitivity and spatial specificity for the inflammation-specific ATP imaging in vivo. Benefiting from the improved spatial selectivity, enhanced signal-to-background ratios were achieved for ATP imaging during acute hepatitis.

An Enzymatically Gated Catalytic Hairpin Assembly Delivered by Lipid Nanoparticles for the Tumor-Specific Activation of Signal Amplification in miRNA Imaging

MicroRNA (miRNA) imaging in disease sites is vital to elucidate their role in cancer progression. However, limited tumor specificity remains a major barrier for traditional amplification approaches due to associated background signal leakage. Here, we report a generalizable approach via the combination of enzymatically triggered catalytic hairpin assembly with lipid nanoparticles (LNPs)-based delivery strategy for tumor-specific activation of signal amplification and therefore sensitive miRNA imaging. The signal amplification is established via engineering of traditional catalytic hairpin assembly with enzymatically activated motifs to achieve triggable miRNA imaging in cancer cells. Furthermore, by the introduction of LNPs to combat biological barriers, we demonstrate that the system enables amplified miRNA imaging in vivo with reduced off-tumor signal, leading to enhanced tumor-to-background contrast compared with traditional methods. This approach that relies on specific triggers and controlled delivery to distinguish miRNA in cancer cells from normal cells should be useful in tumor diagnosis.

Rolling circle amplification (RCA) -based biosensor system for the fluorescent detection of miR-129-2-3p miRNA

Herein, a versatile fluorescent bioanalysis platform for sensitive and specific screening of target miRNA (miR-129-2-3p) was innovatively designed by applying target-induced rolling circle amplification (RCA) for efficient signal amplification. Specifically, miR-129-2-3p was used as a ligation template to facilitate its ligation with padlock probes, followed by an RCA reaction in the presence of phi29 DNA polymerase. The dsDNA fragments and products were stained by SYBR Green I and then detected by fluorescence spectrophotometry. As a result, miR-129-2-3p concentrations as low as 50 nM could be detected. Furthermore, the expression of miR-129-2-3p in breast cancer patients was about twice that in healthy people. Therefore, the results indicated that the RCA-based biosensor system could be a valuable platform for miRNA detection in clinical diagnosis and biomedical study.

Spatially Selective Imaging of Mitochondrial MicroRNAs via Optically Programmable Strand Displacement Reactions

MicroRNA (miRNA) functions are tightly regulated by their sub-compartmental location in living cells, and the ability to imaging of mitochondrial miRNAs (mitomiRs) is essential for understanding of the related pathological processes. However, most existing DNA-based methods could not be used for this purpose. Here, we report the development of a DNA nanoreporter technology for imaging of mitomiRs in living cells through near-infrared (NIR) light-controlled DNA strand displacement reactions. The sensing function of the DNA nanoreporters are silent (OFF) during the delivery process, but can be photoactivated (ON) with NIR light after targeted mitochondrial localization, enabling spatially-restricted imaging of two types of cancer-related mitomiRs with improved detection accuracy. Furthermore, we demonstrate imaging of mitomiRs in vivo through spatiotemporally-controlled delivery and activation. Therefore, this study illustrates a simple methodology that may be broadly applicable for investigating the mitomiRs-associated physiological events.