Investigations Of Ionic Liquid Microemulsion System In The Isolation Of Proteins

As a kind of important biomacromolecules, protein plays an irreplaceable role in the life activities. It is of great importance to develop applicable systems or methods for rapid and efficient separation of various proteins from complex sample matrices for proteomic analysis. In the present study, we aim at developing an effective separation protocol based on ionic liquid microemulsion for the selective isolation of specific protein species of interest.In the first part of the thesis, we reviewed the recent progress in the separation/purification of proteins based on the traditional microemulsion as well as different types of ionic liquid miceoemulsions and their applications.The second part of the thesis focuses on the development of a new ionic liquid microemulsion composed by 1-decyl-3-methylimidazolium bromine (DmimBr) as surfactant, 1-butyl-3-methylimidazolium hexaflourophosphate (BmimPF6) as substitute for traditional organic solvent, and water. The phase diagram of this ionic liquid microemulsion is determined at 25℃. FT-IR spectra, dynamic light scattering and molecular probe technic are utilized to obtain the structural information of the IL microemulsion. When extraction is carried out by mixing 100 μL ionic liquid microemulsion with an equal volume of sample solution with protein species at the concentration of 100 μg mL-1, highly selective extraction for hemoglobin in the presence of bovine serum albumin and cytochrome c is achieved by adjusting to pH 5.0. After extraction, about 55.6% of the retained hemoglobin in the microemulison could be readily recovered by using Britton-Robinson buffer solution at pH 12.0. The practical application of the ionic liquid microemulsion has been demonstrated by selectively extracting hemoglobin from human whole blood, and the excellent separation/purification performance is demonstrated by SDS-PAGE gel electrophoresis assay. The results showed that the hemoglobin could be high selectively isolated from human whole blood in the presence of abundant co-existing protein species. The experiments have showed that the obtained hemoglobin has high purity.