Cholinium chloride as a weak salting-out agent to tune the biomolecules partition behavior in polymer-salt aqueous two-phase systems

Abstract

Aqueous two-phase systems (ATPS) tend to be a suitable method for the extraction and purification of biomolecules. In this work, the cholinium chloride was applied to replace part of the salt concentration, achieving ions at equivalent concentrations, in ATPS composed of salt (NaH2PO, K2HPO4, K3PO4, K2CO3 or K3C5H5O7), poly(propylene)glycol (molecular weight of 400 g mol−1) and water in order to tune the phase properties and behavior and consequently the biomolecules partition behavior. For this, the liquid-liquid experimental data were obtained to evaluate the cholinium chloride effect on the phases diagram in comparison with the ternary system without cholinium chloride. In the same way alkaloids (caffeine and nicotine), phenolic compounds (gallic acid and vanillic acid) and amino acids (l-tryptophan, l-tyrosine, and l-phenylalanine) were used as molecular probes. The obtained result suggests a low kosmotropic characteristic from the cholinium chloride, which resulted in a decrease of the biphasic region when this salt was present in the systems. Beyond that, the partial substitution of salt by cholinium chloride was able to tune the partition behavior of the evaluated biomolecules, whether changing the preferential phase or increasing the extraction efficiency.