Ionic liquids for two-phase systems and their application for purification, extraction and biocatalysis

Abstract

The development of biotechnological processes using novel two-phase systems based on molten salts known as ionic liquids (ILs) got into the focus of interest. Many new approaches for the beneficial application of the interesting solvent have been published over the last years. ILs bring beneficial properties compared to organic solvents like nonflammability and nonvolatility. There are two possible ways to use the ILs: first, the hydrophobic ones as a substitute for organic solvents in pure two-phase systems with water and second, the hydrophilic ones in aqueous two-phase systems (ATPS). To effectively utilise IL-based two-phase systems or IL-based ATPS in biotechnology, extensive experimental work is required to gain the optimal system parameters to ensure selective extraction of the product of interest. This review will focus on the most actual findings dealing with the basic driving forces for the target extraction in IL-based ATPS as well as presenting some selected examples for the beneficial application of ILs as a substitute for organic solvents. Besides the research focusing on IL-based two-phase systems, the "green aspect" of ILs, due to their negligible vapour pressure, is widely discussed. We will present the newest results concerning ecotoxicity of ILs to get an overview of the state of the art concerning ILs and their utilisation in novel two-phase systems in biotechnology.

Extraction and purification of wheat-esterase using aqueous two-phase systems of ionic liquid and salt

“…The presence of high concentrations of salts increased the hydrophobicity of the bottom phase (Zaslavsky et al 1982), in which the solubility of proteins decreased significantly because the large number of salt ions competed for water molecules with proteins while the salvation spheres surrounding the proteins ionized groups were removed (McKee and Mckee 1999) and salting out of proteins took place. Consequently the majority of the proteinic components were moved into the top phase.…”

“…Since then significant progress has been made in the field of ILs-based ATPS. Since the ILs-based ATPS are particularly suitable for the extraction of biocatalysts or their products more and more investigations have been undertaken to study their abilities to extract biomolecules such as protein, incretion, antibiotic, alkaloid and emzyme (Oppermann et al 2011).…”

Evaluating Self-buffering Ionic Liquids for Biotechnological Applications

“…3 The interest in biotechnological applications of ILs is growing not only for enzyme catalysis [4][5][6][7][8] but also for bioseparation process. [9][10] Their potential as media for biocatalytic reactions with remarkable yields 11 has been demonstrated, in addition to their enantioselectivity 12 and enzyme stability. 13 In bioseparations water miscible-ILs hold great potential as a feasible alternative for phase forming agents in aqueous biphasic systems (ABS) to replace conventional polymer and/or salt-rich phases, 14 for the purification of various enzymes including alcohol dehydrogenases, 15 lysozyme, 16 cyclodextrin glycosyltransferase, 17 peroxidases, 18 and lipases.…”

Kinetics and polarity effects in the synthesis of the ionic liquid, 1-hexyl-3-methyl-imidazolium bromide, using compressed CO2

“…Ionic liquids (ILs) are being continually developed for a variety of different applications in diverse areas such as catalytic synthesis [1], separation [2], nanotechnology [3,4], electrochemistry [5,6] and bio-catalysis [7,8]. Diverse publications and patents of novel applications of these solvents, from industry and academia, continue to grow at an exponential rate.…”