Bimetallic and dual-ligands MOFs modified electrochemical sensor for fast and highly sensitive miR-21 detection

MicroRNA-21 (miR-21) has shown great promise as a biomarker for early cancer diagnosis. However, its trace-level abundance in clinical samples complicates point-of-care detection. Herein, we developed a new DNA-modified bimetallic dual-ligand MOF-based electrochemical sensor for highly sensitive and rapid detection of miR-21. The MOF was synthesized using 2,2′-bipyridine-5,5′-dicarboxylic acid (DPDC) and meso‑2,3-dimercaptosuccinic acid (DMSA) as organic linkers, with Ni²⁺/Co²⁺ serving as metal centers. Subsequently, the capture DNA (cDNA) was designed and modified MOF with high porosity and large surface area, significantly enhancing molecular interactions between the cDNA and target miR-21 to boost sensitivity. The developed biosensor exhibits a linear detection range of 10 fM to 100 nM, with a low detection limit of 10 fM and excellent specificity. This method effectively detects miR-21 in blood samples, showcasing strong clinical potential and providing a reliable platform for precision biosensing.