POM@Cu-MOF/Hydrogel Quasi-Solid Electrolyte-Integrated ECL Biosensor for miRNA-155 Detection in Triple-Negative Breast Cancer Diagnosis.

This study developed a novel electrochemiluminescence (ECL) biosensor for detecting miRNA-155, integrating polyoxometalate@metal-organic framework (POM@Cu-MOF) as a luminescent nanoprobe with a highly conductive hydrogel (PIL-Zn-SBMA) as a quasi-solid electrolyte. On the one hand, polyoxometalate was encapsulated in the Cu-MOF through host-guest interactions. Therefore, the modulated local microenvironment in POM@Cu-MOF suppressed low-energy emission and significantly improved the ECL performance of Cu-MOF. On the other hand, zwitterions formed high-speed ion-transport pathways in the PIL-Zn-SBMA hydrogel, providing excellent conductivity. The PIL-Zn-SBMA hydrogel offered an unobstructed ionic compensation pathway for the ECL process and improved the application ability and stability. As a result, the ECL reaction was accelerated, generating strong luminescence signals. Finally, based on the catalytic hairpin assembly amplification strategy, miRNA-155 was captured on the PIL-Zn-SBMA hydrogel and recognized by POM@Cu-MOF. The generated ECL signal can be used for the quantitative detection of miRNA-155 concentration in triple-negative breast cancer (TNBC) tissues within the range of 0.1 fM to 10 nM, with a detection limit of 0.1 fM. This POM@Cu-MOF/hydrogel quasi-solid electrolyte study provided a novel, reliable approach for biomarker detection in clinical diagnosis.