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Proceedings Paper

Fluorescence-based optrodes for alkali ions based on the use of ion carriers and lipophilic acid/base indicators
Author(s): Huarui He; Otto S. Wolfbeis
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Paper Abstract

We present fluorosensors for potassium calcium and ammonium based on the use of ion carriers and a highly fluorescent lipophilic proton carrier. Fluorescent potassium-sensitive membranes have been prepared by dissolving chemically modified Nile Blue and valinomycin in a pvc/plasticizer mixture. Valinomycin being a highly selective potassium carrier binds potassium ion and carries it into the membrane. Simultaneously in order to maintain electro-neutrality of the membrane a proton dissociates from the proton carrier (Nile Blue) dissolved in the pvc membrane and diffuses into the aqueous phase. The dissociation of the protonated amino group of Nile Blue causes its color to change from blue to red. Depending on the choice of the excitation wavelength both the decrease in the fluorescence of the blue species and the increase in the fluorescence of the red species can be monitored. The sensor fully reversibly responds to potassium over the 100 uM to 100 mM concentration range. By replacing valinomycin by carriers for ammonium and calcium ion the respective sensors are obtained. It also is found that the addition of hydroxylic plasticizers to the membrane material considerably accelerates the response time in both directions. While this kind of sensor suffers from cross sensitivity toward pH it has the advantage of full solid-state compatibility (LEDs or diode lasers may be used as light sources). Also because only one kind of fluorophore can be used in almost all kinds

Paper Details

Date Published: 1 March 1991
PDF: 10 pages
Proc. SPIE 1368, Chemical, Biochemical, and Environmental Fiber Sensors II, (1 March 1991); doi: 10.1117/12.24786
Show Author Affiliations
Huarui He, Karl-Franzens Univ. (Austria)
Otto S. Wolfbeis, Karl-Franzens Univ. (Austria)

Published in SPIE Proceedings Vol. 1368:
Chemical, Biochemical, and Environmental Fiber Sensors II
Robert A. Lieberman; Marek T. Wlodarczyk, Editor(s)

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