Biomedical Engineering Reference
In-Depth Information
Fig. 3.2. A. Examples of four different chromophores that have been used to monitor membrane potential. The oxonol
dye, RH155, and its analog RH482 (not shown), are commercially available as NK3041 and NK3630 from Hayashibara
Biochemical Laboratories Inc./Kankoh-Shikiso Kenkyusho Co. Ltd., Okayama, Japan. The oxonol, XXV (WW781) and
styryl, di-4-ANEPPS, are available commercially as dye R-1114 and D-1199 from Invitrogen Molecular Probes, Junction
City, OR. Merocyanine dyes, including XVII (WW375, NK2495), and its analog, NK2761, need negotiation with Hayashibara
Biochemical Laboratories.
B
. The chemical structure (right) and the emission spectrum as a function of calcium concen-
tration of Calcium Green-1. The conjugate with the 10 kD dextran is available commercially from Molecular Probes as
C-3713. Data taken from the Handbook of Fluorescent Probes and Research Chemicals, sixth edition, Molecular Probes.
preparations, and thus, tens of dyes usually have to be tested to
obtain the largest possible signal. A common problem was that
the dye did not penetrate through connective tissue or along
intercellular spaces to the membrane of interest.
The following rules-of-thumb seem to be useful: First, each
of the chromophores is available with a fixed charge which is
either a quaternary nitrogen (positive) or a sulfonate (negative).
Generally, the positively charged dyes have given larger signals in
vertebrate preparations. Second, each chromophore is available
with carbon chains of various lengths. The more hydrophilic dyes
(methyl or ethyl) work best if the dye has to penetrate through
