title: A near-infrared neutral pH fluorescent probe for monitoring minor pH changes: imaging in living HepG2 and HL-7702 cells.
abstract: A near-neutral pH near-infrared (NIR) fluorescent probe utilizing a fluorophore-spacer- receptor molecular framework that can modulate the fluorescence emission intensity through a fast photoinduced electron-transfer process was developed. Our strategy was to choose tricarbocyanine (Cy), a NIR fluorescent dye with high extinction coefficients, as a fluorophore, and 4'-(aminomethylphenyl)-2,2':6',2''-terpyridine (Tpy) as a receptor. The pH titration indicated that Tpy-Cy can monitor the minor physiological pH fluctuations with a pK(a) of approximately 7.10 near physiological pH, which is valuable for intracellular pH researches. The probe responds linearly and rapidly to minor pH fluctuations within the range of 6.70-7.90 and exhibits strong dependence on pH changes. As expected, the real-time imaging of cellular pH and the detection of pH in situ was achieved successfully in living HepG2 and HL-7702 cells by this probe. It is shown that the probe effectively avoids the influence of autofluorescence and native cellular species in biological systems and meanwhile exhibits high sensitivity, good photostability, and excellent cell membrane permeability.
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Engineering Research Center of Pesticide and Medicine Intermediate Clean Production, Ministry of Education, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, Jinan 250014, People's Republic of China. tangb@sdnu.edu.cn
authors.forename: Bo
authors.initials: B
authors.lastname: Tang
authors.forename: Fabiao
authors.initials: F
authors.lastname: Yu
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Lili
authors.initials: L
authors.lastname: Tong
authors.forename: Xia
authors.initials: X
authors.lastname: Duan
authors.forename: Ting
authors.initials: T
authors.lastname: Xie
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000737:chemistry* / Q000473:pathology; D002460:Cell Line; D005456:Fluorescent Dyes / Q000737:chemistry*; D005470:Fluorometry / Q000379:methods*; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000737:chemistry* / Q000166:cytology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008113:Liver Neoplasms / Q000737:chemistry* / Q000473:pathology; D018613:Microscopy, Confocal; D019265:Spectroscopy, Near-Infrared
chemical_list: D005456:Fluorescent Dyes