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：http://pubs.acs.org/doi/abs/10.1021/ac4013539