Reversible Near-Infrared pH Probes Based on Benzo[a]phenoxazine
Wu Liu †, Ru Sun †, Jian-Feng Ge *†（葛健锋）, Yu-Jie Xu ‡, Ying Xu ‡, Jian-Mei Lu *†（路建美）, Isaum Itoh §, and Masataka Ihara *§
†College of Chemistry, Chemical Engineering and Material Science, ‡School of Radiation Medicine and Protection, Soochow University, 199 Ren’Ai Road, Suzhou 215123, People’s Republic of China
§ Drug Discovery Science Research Centre, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
Anal. Chem. 2013, 85，7419–7425
Several benzo[a]phenoxazine derivatives containing substituted N-aromatic groups are evaluated for their pH-dependent absorption and emission properties. Among the compounds exhibiting optical responses under near-neutral and subacid pH conditions, benzo[a]phenoxazine derivatives with an electron-withdrawing aromatic group attached to nitrogen of the imino group show potential application as near-infrared pH sensors. Three water-soluble pH probes based on benzo[a]phenoxazine with different pyridinium structures are designed and synthesized. Their reversible pH-dependent emissions in buffer solution containing 0.1% dimethyl sulfoxide (DMSO) locate in 625–850 nm with the fluorescent enhancement of 8.2–40.1 times, and their calculated pKa values are 2.7, 5.8, and 7.1, respectively. A composite probe containing the three benzo[a]phenoxazines shows a linear pH–emission relationship in the range of pH 1.9–8.0. Real-time detection of intracellular pH using an in vitro assay with HeLa cells is also reported.
链接：//pubs.acs.org/doi/abs/10.1021/ac4013539
