title: Investigating rhodamine B-labeled peptoids: scopes and limitations of its applications.
abstract: The fluorophore rhodamine B is often used in biological assays. It is inexpensive, robust under a variety of reaction conditions, can be covalently linked to bioactive molecules, and has suitable spectral properties in terms of absorption and fluorescence wavelength. Nonetheless, there are some drawbacks: it can readily form a spirolactam compound, which is nonfluorescent, and therefore may not be the dye of choice for all fluorescence microscopy applications. Herein this spirolactam formation was observed by purifying such a labeled peptoid with high performance liquid chromatography (HPLC) and monitored in detail by making a series of analytical HPLC runs over time. Additionally, a small library of eight peptoids with rhodamine B as label was synthesized. Analysis of the absorption properties of these molecules demonstrated that the problem of fluorescence loss can be overcome by coupling secondary amines with rhodamine B.
authors.affiliation: Institute of Organic Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6 D-76131 Karlsruhe, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Birtalan
authors.forename: Birgit
authors.initials: B
authors.lastname: Rudat
authors.forename: Dominik K
authors.initials: DK
authors.lastname: Kölmel
authors.forename: Daniel
authors.initials: D
authors.lastname: Fritz
authors.forename: Sidonie B L
authors.initials: SB
authors.lastname: Vollrath
authors.forename: Ute
authors.initials: U
authors.lastname: Schepers
authors.forename: Stefan
authors.initials: S
authors.lastname: Bräse
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003500:Cyclization; D005456:Fluorescent Dyes / Q000737:chemistry*; D015394:Molecular Structure; D034444:Peptoids / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry; D013194:Staining and Labeling
chemical_list: D005456:Fluorescent Dyes; D034444:Peptoids; D012235:Rhodamines; C029773:rhodamine B