Deployment of MIL-88B(Fe)/TiO Nanotube-Supported Ti Wires as Reusable Electrochemiluminescence Microelectrodes for Noninvasive Sensing of HO from Single Cancer Cells.

As one of the significant intracellular signaling molecules, hydrogen peroxide (HO) regulates some vital biological processes. However, it remains a challenge to develop noninvasive electrodes that can be used for sensing trace HO at the cellular level. Here, we evaluated a high-performance solid-state electrochemiluminescence (ECL) HO sensor based on MIL-88B(Fe) nanocrystal-anchored Ti microwires. Semiconducting TiO nanotubes (TiNTs) vertically grown around a Ti wire an anodization technique act as an intrinsic ECL luminophore. By integrating with MIL-88B(Fe), the synergistic effect of the TiO luminophore and the remarkable peroxidase-like activity of MIL-88B(Fe) enable the resulting HO 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)@TiO microelectrode for single-cell sensing, the electrode was used to detect intracellular HO in a single cell. Moreover, benefiting from the heterojunction of MIL-88B(Fe)/TiO, 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)@TiO 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.