Amino acid solubilization in cationic reversed micelles: factors affecting amino acid and water transfer

Abstract

The aim of this work is to investigate the driving forces involved in amino acid solubilization in cationic reversed micelles, and to determine in which way different parameters affect the reversed micellar structure and amino acid solubilization, in order to select the best conditions to optimize amino acid extraction. To this end, extraction equilibrium experiments were performed using different experimental conditions and three amino acids with different structures: aspartic acid ± a hydrophilic amino acid, phenylalanine ± a slightly hydrophobic amino acid, and tryptophan ± a hydrophobic amino acid. The study of the effect of amino acid related parameters, such as pH and the initial amino acid concentration in the aqueous phase, and the effect of parameters that in¯uence the reversed micellar structure, such as surfactant concentration, ionic strength and co-surfactant concentration, provides useful information about the driving forces involved, solute±micelle interfacial interactions and solute location in the cationic system trioctylmethylammonium chloride (TOMAC)/ hexanol/n-heptane. These parameters can be adjusted to optimize amino acid extraction. It is shown that amino acids with the same isoelectric point can be selectively separated by exploring the different interactions they establish with the reversed micellar interface.

Extraction of lactic acid by phosphonium ionic liquids

“…3 follows that in the solvents containing IL-104 and IL-101 saturated with water there are about 4-8 mol of water per 1 mol of ionic liquid. This is in a good agreement with the results reported by Cardoso et al [34], who investigated the amino acid solubilization in reversed micelles with solutions of trioctylmethylammonium chloride (TOMAC) with hexanol in n-heptane and found the same ratio. They have found reverse micelles with a hydrodynamic radius in the interval from 4 to 6 nm.…”

Extraction of bovine serum albumin using nanoparticulate reverse micelles

“…It was observed that when the surfactant concentration is above 14 mM, the turbidity of the phases increased, making the separation of the phases difficult. An increase in the extraction efficiency with surfactant concentration followed by a decrease is in line with the observations made by other researchers during the forward extraction of different biomolecules [18,26,27]. It was reported that the increase in surfactant concentration increases the number of reverse micelles in the organic phase, favoring higher solute extraction.…”

“…The influence of ionic strength on the diffusion of proteins into reverse micelles was explained mainly as an electrostatic effect [2]. In general, it was observed that as the ionic strength increases, the protein uptake capacity of reverse micelles decreases [26]. However, it was also reported that a minimum salt concentration is needed for the extraction to take place [2].…”

Surface/interfacial changes during polyurethane crosslinking: A spectroscopic study. V *

“…As the ionic strength increases above 0.1 M, the ions form an electrostatic shield around the micelles so the protein molecules cannot interact with them, and hence the percentage of protein in the organic phase decreases. At higher ionic strengths the screening effect decreases resulting in smaller size reverse micelles (squeezing out effect), and proteins are easily expelled out of the micelles (size exclusion effect) 31, 32, 40. The increase in NaCl concentration from 0.05 to 0.10 M increases the swelling from 20 to 76%.…”