Quantitative\nAnalysis of Cell-Free RNA at Attomolar\nLevel Using CRISPR/Cas Digital Imaging Platform

Quantitative analysis of cell-free RNA (cfRNA) in plasma\nsample\ncan be used for screening, diagnosing, and prognosticating of multiple\ndiseases. Here, we report a quantitative CRISPR/Cas digital imaging\nplatform (qCasdip) for the detection of various cfRNAs, including\ncircular RNAs and miRNAs, in clinical samples at the attomolar (aM)\nlevel without the need for preamplification. Digital counting strategy\nprovides qCasdip quantitative ability with a linear detection range\nof 10<sup>2</sup>–10<sup>6</sup> aM. Meanwhile, qCasdip demonstrated\ncfRNA profiling in clinical plasma samples, improving the diagnosis\nof breast cancer. These data highlight the potential of qCasdip to\nquantitatively assess the molecular patterns of specific cfRNA panels\nin plasma, thereby providing a novel liquid biopsy solution to enhance\ndisease diagnosis.