Label-free detection of LncRNA in cancer cells with human telomere G-quadruplex DNA-thioflavin T binding-induced fluorescence

The long noncoding RNAs (lncRNAs) are engaged in multiple biological processes and are often abnormally expressed in various cancers. Although great progress has been made in lncRNA assay, the existing methods usually suffer from poor sensitivity, complicated probe design and fluorophore labeling. To overcome these issues, we develop a label-free fluorescent method to sensitively detect lncRNA in cancer cells based on the integration of duplex-specific nuclease (DSN)-mediated target recycling, TdT-mediated amplification, and Thioflavin T (ThT)/G-quadruplex complex-induced enhanced fluorescence. This method enables sensitive detection of lncRNA HOTAIR with a limit of detection of 1.7 fM. Moreover, it can precisely measure lncRNA HOTAIR in various cancer cells, and even quantify RNA interferences in cancer cells. By simply altering the capture probe sequence, this method can be further exploited to detect different lncRNAs, providing a valuable platform for lncRNA-related biomedical research, clinical diagnosis, and therapeutics.