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 HO in live cells is reported. The Zr-MOF bears a UiO-66 structure and contains 2-boronobenzene-1,4-dicarboxylic acid (BDC-B(OH)) as a framework linker. The activated Zr-UiO-66-B(OH) compound (called 1') is highly selective for the fluorogenic detection of HO 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 HO (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 HO using other analytical methods. Taking advantage of its high selectivity and sensitivity for HO in HEPES buffer, the probe was successfully employed for the imaging of intracellular HO. Imaging studies with MDAMB-231 cells revealed the emergence of bright blue fluorescence after loading with probe 1' and subsequent treatment with HO solution.