Time‐dependent solubilization of IgG in AOT‐brine‐isooctane microemulsions: Role of cluster formation

Abstract

The stability and structure of protein-containing water-in-oil (w/o) microemulsions were investigated by using the large protein immunoglobulin G (IgG, MW 155,000) in a mixture comprised of brine, sulfosuccinic acid bis [2-ethylhexyl]ester (sodium salt), and isooctane. We explored factors affecting the initial uptake of IgG into the w/o microemulsion and its subsequent release to a solid (precipitate) phase, and the kinetics of the latter process. Influences of such parameters as pH, ionic strength, and protein concentration on the solubilization and precipitation of bovine IgG in the organic phase are described. The structure and dynamics in microemulsions containing bovine IgG were probed by using dynamic light scattering, and it was found that the presence of IgG in the microemulsion induced strong attractive forces between the droplets. Based on results obtained by using these various experimental approaches, a model for protein solubilization and release is proposed. In this model, we propose the formation of clusters within which bovine IgG resides and which substantially slow the kinetics of protein release from the droplets to the precipitate phase.

Lipid Carriers: A Versatile Delivery Vehicle for Proteins and Peptides

“…Proteins hosted in microemulsions may alsoˆnd application in research into enzyme activity and protein separation; they can alter surfactant self-association and phase behaviour and can promote the formation of novel solvents and materials. 43) Microemulsions have been used as a model system to understand membrane transport behaviour. 44,45) They can also be used to separate and concentrate proteins, as the solubilisation of individual proteins depends on the protein properties.…”

“…47) The separation of xylose reductase 48) and lysozyme from egg white 49) have been reported using microemulsion technology, and the ability of reversed micellar systems to act as a bioseparation technique for isolation and puriˆcation of proteins has been reviewed by Pires, et al 50) Promising application of the ability of microemulsions to separate and concentrate proteins may be in the separation and puriˆcation of heterogeneous proteins, such as caseins and whey proteins, resulting in large-scale production of individual proteins with increased value. Recently, the incorporation of immunoglobulin G 43) and a-lactalbumin 51) into microemulsion systems formulated with AOT, a non-foodgrade anionic surfactant and isooctane has been reported.…”

Microemulsion‐Mediated Self‐Assembly and Silicification of Mesostructured Ferritin Nanocrystals

“…Microemulsions are versatile reaction media for the confinement and synthesis of inorganic nanoparticles,18 nanowires,19 nanoparticle superlattices,20 and complex hierarchical architectures 21. In addition, microemulsion droplets have been used for the encapsulation of drugs,22 exploration of organic chemical reactions,23 entrapment of functional enzymes,24 and for the separation of protein mixtures 25. Although droplet instability can often be a problem in these applications, herein we demonstrate that protein‐mediated aggregation of the water pools can be exploited to produce discrete ferritin nanocrystals and silicified counterparts with well‐ordered close packed structures.…”

Host–guest extraction of immunoglobulin G using calix[6]arenas

“…The reverse micelle-mediated extraction of proteins involves a solubilization process of the proteins in the reverse micelles. Due to the water pool around the protein denaturation can be minimized [2,[8][9][10][11][12]. The side effect of this is that the electrostatic interactions are not selective, which is a drawback when purifying very complex mixtures.…”