DNA-Tetrahedron-Gated, Ratiometric ECL/SERS Platform for Sensitive miR-155 Analysis

MicroRNA-155 (miR-155) is a pleiotropic regulator of inflammation and immunity that is aberrantly expressed across cancers and has been implicated in neuroinflammatory disorders such as migraine. Notably, migraine associated with patent foramen ovale (PFO) features intermittent right-to-left shunting that can deliver microembolic and inflammatory mediators to the cerebral circulation, amplifying endothelial activation and neuroinflammatory tone in which miR-155 is frequently engaged. Here we report a dual-channel, ratiometric CRISPR biosensor that quantifies miR-155 over seven orders of magnitude and is evaluated in cell-derived matrices. The assay converts target miR-155 into a long DNA trigger via EXPAR and T7 transcription, self-supplies the cognate crRNA, and activates Cas12a collateral cleavage. Cleavage removes a ferrocene quencher from a DNA-tetrahedron (TDN) scaffold on a CsPbBr₃@PDA@Au-modified glassy-carbon electrode, yielding a signal-on electrochemiluminescence (ECL) response; in parallel, disruption of AuNP–perovskite hot spots produces a signal-down surface-enhanced Raman scattering (SERS) readout. Treating the normalized ECL and SERS channels ratiometrically (R = I ECL /I SERS ) mitigates drift and matrix effects. The platform delivers a wide linear working range from 1 aM to 10⁷ aM and a limit of detection down to ∼15 aM using a blank-plus-3σ criterion projected onto the nonlinear calibration. Given the role of miR-155 in neuroinflammation and the vascular shunt physiology of PFO-related migraine, the assay also offers a sensitive route to provide an analytical basis for future studies of circulating miR-155. This CRISPR/EXPAR-powered, ECL-up/SERS-down ratiometric design integrates a low detection limit, broad dynamic range, and improved measurement reliability, supporting future translational studies of disease-related miRNAs.