Measurement of Intraliposomal pH-Changes by Bacteriorhodopsin Using Quantitative Laser Scanning Microscopy

Stefan Lange, Veniamin Galius, and Stefan Fiedler

Abteilung Baugruppentechnologie und Verbindungstechniken, Fraunhofer Institut für Zuverlässigkeit und Mikrointegration, Gustav-Meyer-Allee 25, Geb. 17, D-13355 Berlin, Germany


Light-induced pH-changes in bacteriorhodopsin containing liposomes were measured by quantitative Laser Scanning Microscopy. Proton concentrations, calculated from intraliposomal fluorescence of pyranine (HPTS) are compared to corresponding extraliposomal values and size distribution, evaluated by dynamic light scattering (PCS). The combination of both methods has been found suitable for pH-estimation in minute sample volumes.