Rhodamine-123 , permeation

This test is used to determine whether a membrane has been damaged by exposure to an oxidizer or by some sort of physical attack. In the Rhodamine B test, the membrane module is pressurized with a dye prior to autopsy. If the permeate turns pink, the membrane is probably damaged. Upon autopsy, damaged areas of the membrane will be stained pink. 

In contrast, much more studies have been devoted to the ditfusion of small molecules in the multilayers, because of its importance in applications like permeation membranes or biosensing. Both IR spectroscopy [316] and fluorescence measurements [317] have shown the diffusion of protons in the multilayers, and thus an influence of the pH of the outer solution even far inside the films. The influence of water on the thickness of the multilayers is also well-documented [111,318]. Diffusion of radiolabeled salt ions has also been measured [125,312], Voltamperometry showed that PAH/PAA films had little effect on the diffusion of Fe(CN)g , but that PAH/PSS films could hinder its transport [116], 6-CF [96], acridine orange [81], daunomycin [251], 2 -3 cyclic adenosine monophosphate [252], bisulfite [313], and different diazonium salts [147,313] have been shown to permeate deeply in multilayers built by ESA. Immunoglobulin G (IgG) could permeate or not in a superlattice made of anti-IgG layers and PAH/PSS spacer layers, depending on the thickness of the spacer layer. The diffusion constants of rhodamine and of 2,2,6,6,-tetramethyl-4-piperidinol-l-oxide (TEMPOL) in PAH/PSS multilayers have been quantified [113,114],... 

The influence of thiolated chitosans on the permeation of hydrophilic compotmds (such as peptide drugs) across freshly excised rat intestinal mucosa was evaluated in an Ussing-type chamber. For example, 0.5% (mA) chitosan-TGA combined with the permeation mediator reduced glutathione (GSH) led to a 4.2-fold improvement of rhodamine-123 (Rho-123) permeation across rat intestinal mucosa [48]. In addition, the permeation-enhancing properties of thiolated chitosans was proven... 

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