Paper-based closed Au-Bipolar electrode electrochemiluminescence sensing platform for the detection of miRNA-155

This paper introduces a paper-based closed Au-bipolar electrode (BPE) biosensing system for the rapid and sensitive electrochemiluminescence (ECL) detection of miRNA-155. This microfluidic paper-based sensing platform is formed by wax-printing technology, screen printing method and in-situ Au nanoparticles (NPs) growth to form hydrophilic cells, hydrophobic boundaries, water proof electronic bridge, driving electrode regions and bipolar electrode regions. For rapid and sensitive detection, the cathode of bipolar electrode was modified with the prepared DNA (S1)-AuPd NPs by hybridization chain reaction, in which the target could initiate multiple cycles reaction to load more AuPd NPs which catalyzed H₂O₂ reduction. In addition, a classical ECL system tris (2,2'-bipyridine) ruthenium (II)- tripropylamine (Ru(bpy)₃²⁺/TPrA) exists at the anode of the bipolar electrode. Due to the charge balance between the anode and the cathode of BPE, the ECL signal response of Ru(bpy)₃²⁺/TPrA system was enhanced in the reporting cell. The intensity of ECL was quantitatively correlated with the concentration of miRNA-155 in the range of 1 pM-10 μM with the detection limit 0.67 pM. Moreover, this method paves a novel way for highly sensitive detection of miRNA-155 in clinical application.