A highly effective "naked eye" colorimetric and fluorimetric curcumin-based fluorescent sensor for specific and sensitive detection of H 2 O 2 in vivo and in vitro .

Hydrogen peroxide (H 2 O 2 ) is involved in many important tasks in normal cell metabolism and signaling. However, abnormal levels of H 2 O 2 are associated with the occurrence of several diseases. Therefore, it is important to develop a new method for the detection of H 2 O 2 in vivo and in vitro . A turn-off sensor, 2,2-difluoro-4,6-bis(3-methoxy-4-((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)styryl)-2 H -1,3,2-dioxaborine (DFCB), based on curcumin was developed for the detection of H 2 O 2 . The DFCB, an orange-emitting sensor, was constructed by employing 2,2-difluoro-4,6-bis(4-hydroxy-3-methoxystyryl)-2 H -1,3,2-dioxaborine (DFC) as the main carrier, and 2-(4-bromomethylphenyl)-4,4,5,5-tetramethyl-1,3,2-doxaborolane as the recognition site. The recognition group on the DFCB sensor could be completely cleaved by H 2 O 2 to generate the intermediate DFC, which would lead to a colorimetric change from bright orange to light blue accompanying by a significantly quenched fluorescence, which could be seen by the naked eye. This sensor exhibited a highly specific fluorescence response to H 2 O 2 , in preference to other relevant species, with an excellent anti-interference performance. The sensor DFCB also possessed some advantages including a wide pH response range (6-11), a broad linear range (0-300 μM), and a low detection limit (1.31 μM). The sensing mechanism of the DFCB sensor for H 2 O 2 was verified by HRMS analysis, 1 H-NMR titration and DFT calculations. In addition, the use of the DFCB sensor was compatible with the fluorescence imaging of H 2 O 2 in living cells and zebrafish.