title: Microchamber arrays with an integrated long luminescence lifetime pH sensor.
abstract: A pH probe with a microsecond luminescence lifetime was obtained via covalent coupling of 6-carboxynaphthofluorescein (CNF) moieties to ruthenium-tris-(1,10-phenanthroline)(2+). The probe was covalently attached to amino-modified poly-(2-hydroxyethyl)methacrylate (pHEMA) and showed a pH-dependent FRET with luminescence lifetimes of 681 to 1260 ns and a working range from ca. pH 6.5 to 9.0 with a pKa of 7.79 ± 0.14. The pH sensor matrix was integrated via spin coating as ca. 1- to 2-μm-thick layer into "CytoCapture" cell culture dishes of 6 mm in diameter. These contained a microcavity array of square-shaped regions of 40 μm length and width and 15 μm depth that was homogeneously coated with the pH sensor matrix. The sensor layer showed fast response times in both directions. A microscopic setup was developed that enabled imaging of the pH inside the microchamber arrays over many hours. As a proof of principle, we monitored the pH of Escherichia coli cell cultures grown in the microchamber arrays. The integrated sensor matrix allowed pH monitoring spatially resolved in every microchamber, and the differences in cell growth between individual chambers could be resolved and quantified.
authors.affiliation: Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Poehler
authors.affiliation: Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, 04103, Leipzig, Germany.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Pfeiffer
authors.affiliation: SYNTHON Chemicals, Werkstattstraße 10, 06766, Wolfen, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Herm
authors.affiliation: SYNTHON Chemicals, Werkstattstraße 10, 06766, Wolfen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Gaebler
authors.affiliation: zell-kontakt GmbH, Industriestrasse 3, 37176, Nörten-Hardenberg, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Busse
authors.affiliation: Institut für Analytische Chemie, Universität Leipzig, Johannisallee 29, 04103, Leipzig, Germany. nagl@chemie.uni-leipzig.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Nagl
mesh_terms: D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006863:Hydrogen-Ion Concentration; D049449:Luminescence; D015335:Molecular Probes; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D015335:Molecular Probes
keywords: Bioprocess miniaturization; Escherichia coli cell growth; FRET-based pH imaging; Long-lifetime luminescent pH sensor; Polymeric microcavity array