Triple-signal miRNA detection: A universal biosensor platform based on element labeling and CHA amplification...

MicroRNAs (miRNAs) are short strands of RNA, typically 18-24 nucleotides (nt), which have been linked to the development of neurodegenerative diseases, cardiovascular disease and cancer, etc. However, current miRNA detection methods face significant challenges in sensitivity, specificity, and interference resistance. Here, a universal biosensor platform was developed using element tagging and catalytic hairpin assembly (CHA) amplification strategy for triple-signal miRNA detection by inductively coupled plasma mass spectrometry (ICP-MS) and fluorescence spectroscopy. The key element Yttrium (Y) lying in upconversion nanoparticles (UCNPs) serves as a rare earth metal (REM)-tagged signal carrier coupled with cascade CHA reactions for target recycling. Upon miRNA recognition, structural switching of hairpin probes initiates target release for subsequent amplification cycles, enabling single miRNA molecules to drive multiple CHA reactions and generate abundant UCNPs-containing hybrid complexes. Taking advantage of the naturally low background of REMs in biological systems, the routine ICP-MS mode achieved an ultralow detection limit of 0.24 fM, while fluorescence detection reached 3.8 fM. Single-particle ICP-MS (SP-ICP-MS) mode further reduced detection limit to 0.12 fM. The ICP-MS and fluorescence dual-mode design ensured analytical reliability through signal cross-validation. Significantly, this platform demonstrates remarkable versatility-simple modification of DNA sequences enables adaptation to diverse miRNA targets, offering a promising technical solution for clinical miRNA assays.