Rational design of a selective and sensitive "turn-on" fluorescent probe for monitoring and imaging hydrogen peroxide in living cells.

As one type of reactive oxygen species (ROS), hydrogen peroxide (H 2 O 2 ) plays a key role in regulating a variety of cellular functions. Herein, a fluorescent probe N-Py-BO was well designed and synthesized and its ability for detecting H 2 O 2 by fluorescence intensity was evaluated. In the design, the arylboronate ester group was acted as a reaction site for H 2 O 2 . Upon reaction with H 2 O 2 under physiological conditions, the boronate moiety in the probe was oxidized, followed by detachment from the probe and as a result, a "turn-on" fluorescence response for H 2 O 2 was acquired. Due to the D-A structure formation between N , N '-dimethylaminobenzene and the -CN group and the linkage by thiophene and C[double bond, length as m-dash]C bonds to increase the conjugate length, this probe showed a remarkable red shift of emission wavelength (650 nm) as well as a large Stokes shift (214 nm). An excellent linear relation with concentrations of H 2 O 2 ranging from 2.0 to 200 μM and a good selectivity over other biological species were obtained. Importantly, taking advantage of the low toxicity and good biocompatibility, the developed probe was successfully applied to monitoring and imaging H 2 O 2 and its level fluctuation in living cells, which provided a powerful tool for evaluation of cellular oxidative stress and understanding the pathophysiological process of H 2 O 2 -related diseases.