Fe-PNC Nanoenzyme-Enhanced Closed Bipolar Sensing Platform for Sensitive ECL/Fluorescence Detection and Imaging of miRNA-141.

A closed-bipolar, dual-mode imaging biosensing platform is reported for the ultrasensitive detection and visualization of microRNA-141. The system integrates a T7 Exodriven cascade amplification circuit with an Fe-PNC nanozyme cathodic probe and UiO-67/Ru emitters at the anode, significantly enhancing detection performance through synergistic effects. The Fe-PNC nanozyme, with peroxidase- and catalase-like activities, accelerates H2O2 decomposition and electron transfer, while Ru(bpy)32+ confined within the pores of UiO-67 NPs exhibits enhanced quantum yield and electrochemiluminescence (ECL) efficiency. This design converts trace miRNA-141 into abundant DNA products and markedly amplified ECL signals, while the concomitant release of FITC-labeled strands enables fluorescence (FL) readout. The dual-mode detection strategy, combining ECL imaging and FL imaging, provides mutually validated, high-contrast maps of miRNA-141 with ultralow limits of detection of 1.6 and 0.19 fM, respectively, along with a wide dynamic range. This approach not only improves detection accuracy but also affectively minimizes detection errors, ensuring highly reliable results. The biosensor further demonstrates excellent selectivity, reproducibility, and recoveries of 97.6-102.0% for miRNA-141 determination in spiked human serum, highlighting its promising potential for bioimaging-guided early disease diagnosis.