Selective and Sensitive Sensing of Hydrogen Peroxide by a Boronic Acid Functionalized Metal–Organic Framework and Its Application in Live-Cell Imaging

A new boronic acid functionalized Zr­(IV) metal–organic framework having the capability of sensing H₂O₂ in live cells is reported. The Zr-MOF bears a UiO-66 structure and contains 2-boronobenzene-1,4-dicarboxylic acid (BDC-B­(OH)₂) as a framework linker. The activated Zr-UiO-66-B­(OH)₂ compound (called 1′) is highly selective for the fluorogenic detection of H₂O₂ in HEPES buffer at pH 7.4, even in the presence of interfering ROS (ROS = reactive oxygen species) and other biologically relevant analytes. The fluorescent probe was found to display extraordinary sensitivity for H₂O₂ (detection limit 0.015 μM) in HEPES buffer, which represents a lower value in comparison to those of the MOF probes documented so far for sensing H₂O₂ using other analytical methods. Taking advantage of its high selectivity and sensitivity for H₂O₂ in HEPES buffer, the probe was successfully employed for the imaging of intracellular H₂O₂. Imaging studies with MDAMB-231 cells revealed the emergence of bright blue fluorescence after loading with probe 1′ and subsequent treatment with H₂O₂ solution.