MOF-818 nanozyme-based colorimetric and electrochemical dual-mode smartphone sensing platform for in situ detection of H2O2 and H2S released from living cells

Hydrogen peroxide (H2O2) and hydrogen sulfide (H2S) play a key role in many cellular signaling pathways. The efficient and accurate in situ detection of H2O2 and H2S released from living cells has attracted extensive research interests. Herein, we presented a portable colorimetric and electrochemical dual-mode sensor for detection of cellular secreted H2O2 and H2S based on MOF-818 nanozyme. MOF-818 containing trinuclear copper centers not only possesses excellent peroxidase-like activity under 37 °C and acidic conditions, but also exhibits outstanding electrocatalytic reduction activity to H2O2 (reduction peak potential at −0.08 V vs Ag/AgCl). Meanwhile, the copper sites of MOF-818 can be coordinated with sulfide, reducing the catalytic activity of MOF-818. As a result, the colorimetric and electrochemical sensing of H2O2 and H2S were established based on “signal-on” and “signal-off” strategies, respectively. Additionally, the combination of a smartphone and a miniature electrochemical analyzer enables dual-mode colorimetric and electrochemical sensing platform for in situ detection of H2O2 and H2S released from live cells. This portable dual-mode sensor based on MOF nanozyme not only opens a new path for point-of-care testing, but also has potential applications in the field of cell biology and clinical diagnosis.