Elaine, I would try to use e.g. a FITC conjugated (mouse) antibody directed to a surface antigen of a "carrier cell line" (or, alternatively, beads coated with goat-anti mouse Ig) for this approach. Because fluorescence emission (and absorbance) spectra of FITC are strongly pH dependent in the range > pH 8 (highest emission) to < pH 5 (low emission), this should allow determination of extracellular pH by FACS. See Molecular Probes Handbook .. for more information on pH dependence of fluorochromes. Best regards Georg ________________________________________________________________________ Elaine Kunze wrote: Is it possible to attach a pH sensitive fluorochrome to a microsphere to detect (by flow) pH changes (pH 6 to 7) in the surrounding fluid? Most of the pH probes are designed with intracellular changes in mind. **************************************************************************** Elaine Kunze Flow Cytometry.....Image Analysis... Life Sciences Consortium 8B Althouse Laboratory (814-863-2762) Penn State University ------------------------------------------------------------------------ H.G. Kreysch Merck KGaA Biomed Fo/IMO - A25/410 Tel.: (49)6151 - 72 7323 Frankfurter Str. 250 FAX: (49)6151 - 72 7398 D-64271 Darmstadt E-Mail: kreysch@merck.de
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