Structure-Switchable Hairpin-Powered Exponential Replications for Sensing Attomolar microRNA-Related Single Nucleotide Polymorphisms in Human Cancer Tissues with Zero Background.

MicroRNA (miRNA)-related single-nucleotide polymorphisms (miR-SNPs) are a novel class of genetic variations involved in multiple cellular functions, and they have emerged as promising biomarkers for cancer diagnostics and prognostics. Herein, we demonstrate for the first time the structure-switchable hairpin-powered exponential replications for sensing attomolar miR-SNPs in human cancer tissues with zero background. In the presence of target miR-196a2T, hairpin probes (i.e., HP1 and HP2) are splinted together to construct the dumbbell-shaped probe (DSP) with SplintR ligase catalysis. Once the DSP is formed, the self-primed polymerization extension and linear FIP/BIP-primed strand displacement DNA synthesis (SDS) are automatically repeated to activate self-circulated exponential amplification, producing large amounts of double-stranded DNAs (dsDNAs) which can be real-time monitored using SYBR Green I. This nanodevice can detect miR-196a2T with an ultralow detection limit of 2.46 aM; distinguish rare miR-196a2 SNP with a selectivity factor of 0.001%; and even profile miR-196a2T in human tissues for nonsmall cell lung cancer (NSCLC) diagnosis, risk assessment, and cancer type prediction. Notably, this nanodevice can be rapidly and homogeneously used in one tube in a real-time and label-free manner, providing a powerful point-of-care platform for noninvasive diagnostics and prognostics of miR-SNPs-related human cancers.