Application of an l-Cysteine-Enhanced Ag NCs@C NF Amplification-Free ECL Biosensor for miRNA

Even though a lot of research shows that blood miRNA-155 is a specific, early stage biomarker for sepsis and associated consequences, current detection techniques need to be improved. In this work, we created Ag NCs@C NF nanocomposite luminous materials using carbon nanoflowers (C NFs) as a framework. The Ag NCs@C NF signal is much improved by the addition of l-cysteine (l-Cys), causing the biosensor response to change from "ON" to "super ON." By modifying the hammerhead ribozyme (HHR) into an artificial allosteric blocking ribozyme (BR_miRNA-155) that specifically binds to miRNA-155, this ribozyme rapidly and repeatedly cleaves locked crRNA in the presence of miRNA-155, enabling non-nucleic acid amplification-based miRNA detection. This amplification-free electrochemiluminescence (ECL) biosensor system detects miRNA-155 within a range of 100 aM-100 nM, with a limit of detection (LOD) of 47.4 aM. Additional tests demonstrating specificity, sensitivity, stability, and reproducibility also yielded excellent performance. This technology opens new avenues for the early diagnosis of sepsis and its complications.