An RNase domain-dependent microRNA detection with DNA-spiked nanocage for accurate cancer diagnosis.

Cancer-associated microRNAs are promising biomarkers for early cancer diagnosis. However, current microRNA detections - which are based on polymerase chain reaction, microarray analysis, Raman scattering, or various electrochemical assays - rely on multi-step analysis including amplification of microRNA and/or read-out signals, often causing inaccuracy despite using elaborate instruments, which remains a major challenge. Here, we describe an RNaseH1-dependent, amplification-free detection of microRNAs, which is based on Förster resonance energy transfer (FRET) between donor (single-stranded DNA probe (ssDNA)-spiked, green fluorescent nanocage) and acceptor (RNaseH1-linked, orange fluorescent protein) and enables reliable cancer diagnosis with high accuracy for human lung and gastric cancer patients and healthy donors by directly quantifying serum microRNA targets. Notably, unlike traditional ensemble FRET, this FRET platform senses molecular interactions between ssDNA and miRNAs and conformational changes of their hybrid helices and thus differentiates even a single-base mismatch, which holds significant promise for reliable, clinical cancer diagnosis.