Nucleic Acid-Functionalized Metal–Organic Framework-Based Homogeneous Electrochemical Biosensor for Simultaneous Detection of Multiple Tumor Biomarkers

Simultaneous detection of multiple tumor biomarkers is in great demand for early and accurate cancer diagnosis. A homogeneous electrochemical biosensor has been proven to possess high sensitivity, but achieving simultaneous detection of multiple tumor biomarkers is still a challenge. Herein, we develop a novel homogeneous electrochemical biosensor for simultaneous detection of multiple tumor biomarkers based on the functionalized metal–organic frameworks (MOFs). The functionalized MOFs were prepared by using porous UIO-66-NH₂ as nanocontainer to load electroactive dyes and dsDNA as a gatekeeper to cap MOFs. In this context, two functionalized MOFs (MB@UIO and TMB@UIO) were fabricated and applied to simultaneous detection of let-7a and miRNA-21, used as the proof-of-concept analytes. The recognition and hybridization of P_X with target miRNAs impel the generation of RNA–DNA complexes, which separated from MOFs and allowed the electroactive dyes to be released. In comparison with the case when target miRNAs are absent, two stronger signals are recorded, and dependent on target miRNA concentrations. Thus, simultaneous detection of let-7a and minRNA-21 is achieved, with detection limits down to 3.6 and 8.2 fM, respectively, comparable or lower than those of reported strategies that concentrated on single miRNA detection. Moreover, the proposed biosensor has also been successfully applied for simultaneous detection of target miRNAs spiked in serum samples. Therefore, the proposed strategy was expected to provide more information for early and accurate cancer diagnosis and was an useful application in disease diagnosis and clinical biomedicine.