A novel methylenemalononitrile-BODIPY-based fluorescent probe for highly selective detection of hydrogen peroxide in living cells

Abstract

Hydrogen peroxide (H₂O₂) plays vital roles in oxidative stress and signal transduction in living organisms, and its abnormal levels could be linked to many diseases. Despite numerous efforts spent, it is still urgent and of high importance to develop better H₂O₂ probes with good selectivity, high sensitivity and low backgrounds. To this end, a novel boron dipyrromethene (BODIPY)-based fluorescent probe with an electron-withdrawing methylenemalononitrile at the meso position has been rationally designed, successfully synthesized and investigated for detection of H₂O₂ in aqueous solutions and living cells, which exhibited high selectivity and sensitivity, fluorescent "turn-on" phenomenon at 540 nm, and ratiometric changes from 506 to 540 nm. Upon exposure to H₂O₂, a strong fluorescent emission at 540 nm appeared and the corresponding quantum yields changed from 0.009 to 0.13. The detection limit towards H₂O₂ was calculated to be 31 nM by the linear fluorescence change at 540 nm in the H₂O₂-concentration ranging from 2 to 10 μM. This probe was applicable in a pH range from 6 to 10. Meanwhile, the sensing mechanism was also confirmed by the ¹H NMR and mass spectrometry, suggesting that the above changes might be ascribed to the quick addition and oxidization of the double bond. Furthermore, confocal imaging results also showed great enhancement of intracellular fluorescence upon exposure to H₂O₂ and PMA in RAW264.7 cells, unambiguously confirming its great potentials as a fluorescent probe for highly sensitive detection of both exogenous and endogenous H₂O₂ in living cells.

Keywords: BODIPY; Fluorescent probe; Hydrogen peroxide; Methylenemalononitrile.