Bimetallic CuCo-based metal-organic framework/graphene oxide composite-modified electrode as an efficient miRNA-208a detection biosensing platform.

MicroRNA-208a (miR-208a), a cardiac-specific miRNA encoded within the Myh6 gene intron, is critically involved in cardiac pathologies such as myocardial remodeling and arrhythmia. Its recent identification in the bloodstream has generated significant clinical interest as a non-invasive biomarker for the early diagnosis of myocardial infarction, underscoring the need for reliable pre-infarction screening methods. In this study, a novel bimetallic CuCo-based metal-organic framework/graphene oxide (CuCo-MOF/GO) composite was synthesized to fabricate an electrochemical biosensor for detecting miR-208a. Characterization revealed that the composite possesses a unique three-dimensional nanosheet layered structure with highly dispersed bimetallic active sites. This architecture not only enhances the electrode's electron transfer capability but also, through abundant surface functional groups, facilitates hydrogen bonding and π-π stacking interactions with the complementary RNA capture probe (RNAc). These intermolecular forces ensure strong affinity and stable anchorage of the RNAc onto the modified electrode surface. Coupled with the inherent electrochemical activity of the material, these features confer exceptional detection performance to the biosensor. The constructed BSA/RNAc/CuCo-MOF/GO/GCE (bovine serum albumin, BSA; glassy carbon electrode, GCE) electrode demonstrated a wide linear detection range from 1 zM to 1 pM for miR-208a, with a remarkably low limit of detection (LOD) of 1.27 zM (S/N = 3). Furthermore, the biosensor exhibited excellent selectivity, stability, acceptable reproducibility, and accurate detection in human serum samples, highlighting its strong potential for application in the early diagnosis of cardiovascular diseases.