Argonaute-Coupled Rolling Circle Amplification Enables the Rapid and Sensitive Detection of 8-Oxoguanine-Modified miRNA

8-Oxoguanine (o⁸G), a prominent oxidative RNA modification linked to aging, cancer, and cardiovascular pathologies, presents significant detection challenges due to its structural lability and sequence-dependent mutagenic effects. Current methodologies struggle to achieve rapid and sensitive identification of o⁸G-modified microRNAs (miRNAs), particularly in user-friendly operations. To address this limitation, an argonaute-integrated detection (AID) system was developed that synergizes the sequence-specific cleavage activity of mesophilic Argonaute (Ago) with rolling circle amplification (RCA) for the o⁸G-modified target selective amplification and quantification. Our strategy exploits the unique property of Ago to stall cleavage within o⁸G-modified miRNAs, enabling the selective cleavage of unmodified RNAs while preserving o⁸G-modified miRNA for subsequent RCA-mediated signal amplification. The AID platform achieved picomolar sensitivity with a single-nucleotide resolution. The isothermal reaction of this workflow permitted integration into a field-deployable device capable of the visual readout by the naked eye or smartphone, demonstrating a detection limit of pM for o⁸G-modified RNAs within hours. This portable system combines molecular specificity with operational simplicity, offering potential for clinical diagnostics through the rapid detection of oxidative RNA biomarkers without the need of expensive equipment, while also providing a versatile tool for mechanistic studies of epigenetic regulation in related diseases.