A red-emitting styrylnaphthalimide-based fluorescent probe providing a ratiometric signal change for the precise and quantitative detection of HO.

A red-emitting and ratiometric fluorescence probe 1 for detecting HO, based on a styrylnaphthalimide-boronate ester was developed. Upon a HO-mediated hydrolysis of boronate ester, probe 1 was transformed to 2 with a ratiometric fluorescence change, decrease at 535 and increase at 640 nm. It was also found that the fluorescent reaction of 1 with HO in solution could be completed within 10 min and the detection limit was estimated to be 0.30 μM. Moreover, this ratiometric change was highly selective for HO over other redox species, metal ions, and anions. Also, this system was found to be capable of detecting HO in the pH range of 6-9. Furthermore, probe 1 was preferentially accumulated into the endoplasmic reticulum (ER) in the live HeLa cells, and an increased HO level in the presence of an ER stress inducer, thapsigargin was revealed.