Yan-Hua Zhana, Xiao-Jun Lib, Ru Suna, *（孙如） , Yu-Jie Xub, Jian-Feng Gea, c, *（葛健锋）
a College of Chemistry, Chemical Engineering and Material Science, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Soochow University, 199 Ren’Ai Road, Suzhou, 215123, China
b School of Radiation Medicine and Protection, Medicine College of Soochow University, Suzhou, 215123, China
c Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, 215163, China
Analytica Chimica Acta Volume 933, 24 August 2016, Pages 175–181
In this paper, the design of a lysosome-targetable pH probe that has a fluorescent OFF (pH = 4) to ON (pH = 5–6) response is described to identify lysosomes in normal cells. The mechanism of photoinduced electron transfer with a fluorophore-based reaction (FBR-PET) was proposed. Benzo[a]phenoxazines with electro-donating aryl groups were selected, its (2,5-dimethoxyphenyl)imino-, (2-hydroxyphenyl)imino- and (2-hydroxy-5-methoxyphenyl)- imino-derivatives (probes 1a−c) were prepared and their optical responses towards pH were evaluated; their fluorescence pH titration experiments gave regularly changes with the increasing electro-donating abilities at the linked aryl groups, the (2-hydroxy-5-methoxyphenyl)iminobenzo[a]phenoxazine (probe 1c) exhibited a nearly OFF−ON response at 580–800 nm. All probes were reversible, and they showed excellent selectivity toward the proton over other competitive species. Fluorescence confocal images were performed with HeLa, KB cancer cells and V79 normal cells, probes 1a−c are all lysosome-targetable pH probes, and benzo[a]phenoxazine with (2-hydroxy-5-methoxyphenyl)imino-group (probe 1c) has potential applications in selective differentiation of normal cells from cancer cells.