Hydrophobicity-Gated Glass Nanopipettes for In Situ Monitoring of Hydroxyl Radicals During Single-Cell Physiological Processes

Hydroxyl radicals (•OH) are one of the strongest oxidizing free radicals in reactive oxygen species (ROS) and participate in the regulation of normal physiological metabolism and pathological damage in cells. Therefore, in situ accurate quantitative detection of •OH in living cells is of critical scientific and clinical significance. Herein, we report an effective and facile nanopipette-based platform for monitoring intracellular •OH concentration changes in single cells under oxidative stress and during pyroptosis. Hydrophobic hexanethiol (HEX) was self-assembled on the inner surface of gold nanoparticle-modified glass nanopipettes through the formation of Au−S bonds. The HEX layer can be stripped away upon selective cleavage of Au−S bonds induced by •OH, resulting in the altered hydrophobicity of the inner walls and a measurable change in the ionic current at the nanopipette tip. By virtue of this nanodevice, •OH levels were successfully quantified within individual cells during oxidative stress under different conditions. This strategy enables sensitive, convenient in situ quantification of intracellular •OH, holding great promise for investigating •OH-related oxidative stress under various physiological and pathological conditions.