Ultrasensitive electrochemiluminescence assay of tumor cells and evaluation of H2O2 on a paper-based closed-bipolar electrode by in-situ hybridization chain reaction amplification

Abstract

In this manuscript, a disposable paper-based analytical device comprised of a closed bipolar electrode (BPE) was fabricated for the ultrasensitive electrochemiluminescence (ECL) detection of intracellular H₂O₂ and the number of cancer cells. In this approach, wax printing was used to fabricated reaction zone, and carbon ink-based BPE and driving electrodes were screen-printed into the paper. AuPd nanoparticles (NPs), which served as a carrier of the capture aptamer and as the catalyst for the ECL reaction of luminol and H₂O₂, were used to modify the BPE. Luminol/Au NPs were attached to the surface of the captured cells via hybridation chain reaction with two hairpin structure DNA labelled luminol/Au NPs. In the stimulation of phorbol myristate acetate, The coreactant H₂O₂ was released from the target cells. The ECL response of the luminol-H₂O₂ system was related to the number of cancer cells in the testing buffer, which served as a quantitative signal for the determination of cancer cells and the concentration of H₂O₂. In order to decrease the external voltage, K₃[Fe(CN)₆] was introduced in the cathode resevoir of BPE because it gained electrons at the cathode more easily than oxygen. The ECL intensity was quantitatively related to the concentration of MCF-7 in the range of 1.0 × 10²-1.0 × 10⁷ cells/mL. The detection limit was 40 cells/mL and it showed good specificity for cells with high overexpression of mucin-1 receptor, it was concluded that the developed protocol could be effectively utilized for the detection of MCF-7 cells.

Keywords: AuPd nanoparticles; Bipolar electrode; Electrochemiluminescence; Hybridization chain reaction; Tumor cells.