An ultrasensitive electrochemiluminescence biosensor for MicroRNA detection based on luminol-functionalized Au NPs@ZnO nanomaterials as signal probe and dissolved O2 as coreactant

In this work, the ZnO nanostars with excellent catalytic performance were firstly used as the coreaction accelerator of luminol-O-2 system to construct a biosensor for ultrasensitively detecting microRNA-21 (miRNA-21) in cancer cells. Specifically, ZnO nanostars could expedite the reduction of dissolved O-2, generating more reactive oxygen species (ROSs) to extremely promote electrochemiluminescence (ECL) luminous efficiency of luminol. Thus luminol-functionalized Au NPs@ZnO (L-Au NPs@ZnO) nanomaterials were employed as signal probe to fabricate sensing nano-platform for achieving significant ECL emission as signal on state. Moreover, upon the addition of a tiny minority of target miRNA-21, massive ferrocene (Fc) could be immobilized on the sensing interface through hybridization chain reaction (HCR) triggered-DNA dendrimers self-assembly, in which Fc consumed dissolved O-2 for prominently quenching the ECL emission of signal probe and then reached a signal off state. As a result, the biosensor performed a good linearity in 100 aM - 100 pM and a low limit of detection (LOD) down to 18.6 aM. In general, this work utilized a new coreaction accelerator as an efficient amplification approach for ultrasensitively detecting target analyses, providing a promising approach in luminol-centric ECL bioanalysis fields.