title: Cell-Penetrating Peptide Spirolactam Derivative as a Reversible Fluorescent pH Probe for Live Cell Imaging.
abstract: A colorless and nonfluorescent spirolactam derivative, RhB-R12K, was synthesized by amide condensation between the carboxyl group of rhodamine B (RhB) and the amino group of cell-penetrating peptide (CPP). The fluorescence intensity of RhB-R12K sharply increased as the pH value decreased from 8.0 to 4.9, demonstrating sensitive and reversible response to intracellular pH distribution. This CPP probe was completely water soluble, had low cytotoxicity, was membrane permeable, and was suitable for pH measurement in various organelles by choosing organelle-specific CPP sequences. Interestingly, CPPs acted not only as carriers but also as indispensable parts of fluorophores here. The presence of active groups on the peptides potentially allows for modification with additional dyes to construct multifunctional and ratiometric probes for cell imaging.
authors.affiliation: Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Tsinghua University , Beijing, 100084, P.R. China.
authors.forename: Meng-Chan
authors.initials: MC
authors.lastname: Xia
authors.affiliation: Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Tsinghua University , Beijing, 100084, P.R. China.
authors.forename: Lesi
authors.initials: L
authors.lastname: Cai
authors.affiliation: Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Tsinghua University , Beijing, 100084, P.R. China.
authors.forename: Sichun
authors.identifier: 0000-0001-8927-2376
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Tsinghua University , Beijing, 100084, P.R. China.
authors.forename: Xinrong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D002463:Cell Membrane Permeability; D002470:Cell Survival; D057846:Cell-Penetrating Peptides / Q000737:chemistry* / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000493:pharmacokinetics; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007769:Lactams / Q000737:chemistry* / Q000493:pharmacokinetics; D018613:Microscopy, Confocal / Q000379:methods; D061848:Optical Imaging / Q000379:methods; D012235:Rhodamines / Q000737:chemistry* / Q000493:pharmacokinetics; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D057846:Cell-Penetrating Peptides; D005456:Fluorescent Dyes; D007769:Lactams; D012235:Rhodamines; C029773:rhodamine B