Element-bridged dual-walker amplification for sensitive detection of multiple miRNAs by inductively coupled plasma mass spectrometry

The simultaneous detection of multiple microRNAs (miRNAs) is critical for advancing precise disease diagnosis and treatment strategies. Herein, we introduce a novel method for the sensitive detection of multiple miRNAs using inductively coupled plasma mass spectrometry (ICP-MS), based on a platinum group element-bridged DNAzyme dual-walker amplification system. Upon binding to target miRNAs, the terminal of DNAzyme is released, triggering two DNAzyme-mediated ribonucleotide hydrolysis walking processes driven by Mg²⁺. These DNAzyme-walking sequences are recycled, enabling the continuous cleavage of substrate strands. After magnetic separation, the generated element pairs are quantified by mass spectrometry, enabling simultaneous and highly sensitive detection of multiple miRNAs. The method demonstrates a linear detection range from 5 fM to 10 pM with detection limits of 1.8 fM for miRNA-21, 1.1 fM for miRNA-199a, and 1.5 fM for miRNA-499, respectively.Furthermore, the approach exhibits remarkable specificity, making it suitable for detecting miRNAs in human serum. By demonstrating such a high sensitivity and specificity, this DNA walker-based sensing strategy holds significant potential for the development of versatile platforms to detect other miRNAs at varying expression levels.