Application of rhodamine‐B to interaction studies in proteins and simple model systems

Abstract

With rhodamine‐B used as an indicator, the relative acidities of selected phenols and alcohols as model hydrogen donors have been determined in toluene solution. The method involves measurement of the change from colorless rhodamine to the colored zwitterionic form produced by the hydrogen donor compound. The method has been applied to the determination of equilibrium constants for the interaction of phenol with dimethyl formamide, benzyl acetate and dioxane; the measured constants are in accord with those obtained for the same pairs by Flett (J. Soc. Dyers Colourists, 68, 59–64 (1952)), who employed infrared analysis. Consideration is given to partition of the dye between toluene and water, as influenced by hydrogen bonding and by nonelectrostatic interactions. Forces of interaction which tend to bind the dye in one phase decrease its activity in that phase and consequently reduce its tendency to move from this phase to the other. With incorporation of propiolactone polymer into the wool fiber, the activity of the dye in the fiber is reduced in relation to nonpolar as well as to aqueous solutions, and the modified wool exhibits greatly improved dyeing properties. The dye is useful also for the determination of critical micellar concentration of fatty acid soaps in aqueous solution. It also shows markedly increased binding by heat‐denatured as compared with native egg albumin, and by acetylated, as compared with normal, wool.

Fluorescence correlation spectroscopy, raster image correlation spectroscopy, and number and brightness on a commercial confocal laser scanning microscope with analog detectors (Nikon C1)

“…The concentration of the Rhodamine B solutions in water was determined using a Shimadzu dual beam spectrophotometer. The measurements were made in a 1 cm pathlength cuvette using an extinction coefficient of ε = 111 M/cm (0.1%, 550 nm) (Lundgren and Binkley, 1954). The DiIC 18 stock concentration was determined in MeOH using an extinction coefficient of ε = 148 M/cm (0.1%, 549 nm) (Invitrogen, Carlsbad, CA).…”

Mechanism of Ion Transfer in Supported Liquid Membrane Systems: Electrochemical Control over Membrane Distribution

“…Challenging properties of the transfer, such as the direction and extent of the diffusion, concentration distribution, and dissociation equilibrium, were studied using a model molecule, rhodamine B [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-diethylammonium chloride. Rhodamine B (RB) is a xanthene derived fluorescent dye with strong UV–vis absorption used predominantly as a tracer in biotechnology applications. − Permeability of RB was previously studied in pharmaceutical research and wastewater treatment applications . The molecule contains amino- and carboxy-functional groups, is predominantly uncharged in the aqueous phase at neutral pH, being a weak base with p K a value of 3.2–3.7, , and has an aqueous diffusion coefficient of 4.27 × 10 –6 cm 2 s –1 .…”

A Fast and Simple Qualitative Method for Screening Oleaginous Yeasts on Agar

“…479; IUPAC name N-[9-(ortho-carboxyphenyl)-6-(diethylamino)-3H-xanthen-3-ylidene] diethyl ammonium chloride), is a highly water soluble, basic red dye of the xanthene class. This dye has been used to stain lipids in different applications [ 16 , 20 , 22 , 23 ]. At the prepared concentrations used in this work and under the proposed conditions, this dye is neither a pollutant nor a hazardous substance.…”