LAUSR

As one of the significant intracellular signaling molecules, hydrogen peroxide (H2O2) regulates some vital biological processes. However, it remains a challenge to develop noninvasive electrodes that can be used for sensing trace H2O2 at the cellular level. Here, we evaluated a high-performance solid-state electrochemiluminescence (ECL) H2O2 sensor based on MIL-88B(Fe) nanocrystal-anchored Ti microwires. Semiconducting TiO2 nanotubes (TiNTs) vertically grown around a Ti wire via an anodization technique act as an intrinsic ECL luminophore. By integrating with MIL-88B(Fe), the synergistic effect of the TiO2 luminophore and the remarkable peroxidase-like activity of MIL-88B(Fe) enable the resulting H2O2 sensor an ultrahigh sensitivity featuring a minimum detection limit of 0.1 nM (S/N = 3), long-term stability, high durativity, and wide-range linear response to a concentration of up to 10 mM. To demonstrate the concept of a MIL-88B(Fe)@TiO2 microelectrode for single-cell sensing, the electrode was used to detect intracellular H2O2 in a single cell. Moreover, benefiting from the heterojunction of MIL-88B(Fe)/TiO2, the microelectrode was found to exhibit excellent photocatalytic activity in the visible-light range, that is, the sensor surface can be self-cleaning after a short visible-light treatment. These advanced sensor characteristics involving easy reusability reveal that the MIL-88B(Fe)@TiO2 microelectrode is a new platform for cytosensing. This study provides a new strategy to design semiconductor materials with arbitrary shape and size, allowing for profound applications in biomedical and clinical analysis.