In Situ Imaging of Endogenous Hydrogen Peroxide Efflux from Living Cells via Bipolar Gold Nanoelectrode Array and Electrochemiluminescence Technology

The integration of a closed bipolar electrode (c-BPE) array and electrochemiluminescence (ECL) detection received a boost in applications in the detection of cell adhesion and disease-related biomarkers. This work proposed a gold nanorod array based c-BPE–ECL system to realize an in situ image of endogenous hydrogen peroxide (H2O2) efflux from living cells and parallel analysis of endogenous H2O2 released from multiple cells by converting electrochemical signals into optical signals. The gold nanorod array with high density was prepared by a repeating chronopotentiometry procedure with anodic aluminum oxide (AAO) membrane as a template. The c-BPE array was fabricated by assembling poly(dimethylsiloxane) (PDMS) chips on both sides of the gold nanorod array. When an appropriate driving potential is applied, H2O2 generated from living cells at the sensing pole was reduced on the gold nanorod, triggering the oxidation of the ECL reagent at the reporting pole, which allowed the detection of H2O2 released from living cells. Under phorbol myristate acetate (PMA) stimulation, H2O2 released from living HeLa, HepG2, MCF-7, and LO2 cells was determined to be 47, 32.4, 25.7, and 6.3 μM, respectively. This indicated that the amount of H2O2 released from PMA-stimulated cancer cells was significantly higher than that from the stimulated normal cells. This work presented a new approach for in situ imaging of H2O2 released from living cells and could also be used to detect other electrochemically active or non-electrochemically active molecules through simple cell surface modification, which may have potential applications in cell apoptosis study and disease diagnosis.