Backward extraction of reverse micellar encapsulated proteins using a counterionic surfactant

Abstract

The back‐extraction of proteins encapsulated in AOT reverse micelles was performed by adding a counterionic surfactant, either TOMAC or DTAB. This novel backward transfer method gave higher backward extraction yields compared to the conventional method with high salt and high pH of the aqueous stripping solution. The protein activity was maintained in the resulting aqueous phase, which in this case had a near neutral pH and low salt concentration. A sharp decrease of the water content was observed in the organic phase corresponding to protein back‐extraction using TOMAC. The backward transfer mechanism was postulated to be caused by electrostatic interaction between oppositely charged surfactant molecules, which lead to the collapse of the reverse micelles. The back‐extraction process with TOMAC was found to be very fast; more than 100 times faster than back‐extraction with the conventional method, and as much as 3 times faster than forward extraction. The formation of 1:1 complexes of AOT and TOMAC in the solvent phase was observed, and these hydrophobic complexes could be efficiently removed from the solvent using adsorption onto Montmorillonite in order for the organic solvent to be reused. A second cationic surfactant, DTAB, confirmed the general applicability of counterionic surfactants for the backward transfer of proteins. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 593–601, 1999.

Process optimization for reverse micellar extraction of stem bromelain with a focus on back extraction

“…Addition of counterionic surfactant causes electrostatic interaction between oppositely charged surfactants, which further results in destabilization of reverse micelles. 22,26 It was observed that addition of CTAB does not improve the BEE significantly. Only 9.42% of protein was back extracted into the stripping phase from the organic phase.…”

“…Reverse micelles are thermodynamically stable, but under Brownian motion, they constantly collide with each other and this results in temporary fusion of two reverse micelles. 26 Mathew and Juang 46 have reported that a strong interaction between the solubilized proteins and micelles induces the micelle-micelle interaction or reversed micellar cluster formation, resulting in a decrease in back extraction fractions. Hence, the control of micelle-micelle interactions might become an immensely significant factor for the success of back extraction of the proteins.…”

“…22,25 To achieve maximum back extraction, researchers have investigated several other back extraction techniques. Jarudilokkul et al 26 and Mathew and Juang 22 used tri-o-cetylmethylammonium chloride as a counterionic surfactant to recover proteins from the sodium bis(2-ethylhexyl) sulfosuccinate (AOT) isooctane system. The protein recovery using counterionic surfactant is based on the electrostatic interaction between the oppositely charged surfactant molecules, which leads to the collapse of reverse micelles.…”

Reverse Micelle Induced Flipping of Binding Site and Efficiency of Albumin Protein with an Ionic Styryl Dye

“…10 Proteins and enzymes are solubilized into reverse micelles, maintaining their activities and native structures, and can be back-extracted. 11,12 It has been found that the factors such as water content (the molar ratio of water to surfactant, namely, W 0 ) and micelle size, 13 aqueous phase pH and ionic strength, 14 surfactant type and concentration, 15 and cosurfactant 16 affect the protein solubilization and characteristics based on the interactions between reverse micelles and proteins. Moreover, adding proteins to the reverse micelles can alter surfactant self-assembly and phase behavior which can affect the protein efficiency.…”

Electrochemical Aspects of the Reverse Micelle Extraction of Proteins

“…To understand the extraction mechanism, many efforts have been made to study the effects of various experimental conditions, which include the natures and concentrations of proteins, surfactants, and aqueous electrolytes and the pH of the aqueous phase. [2][3][4][5][6][11][12][13][14][15][16][17][18][19][20][21] It is generally recognized that the electrostatic interactions between a protein and surfactants play an important role in the formation of reverse micelles containing proteins. It has also been claimed that the electrostatic interactions of a protein with a bulk oil/water (O/W) interface play the dominant role in the inclusion of a protein in a reverse micelle at the O/W interface.…”