Preparation Of Polymeric Ionic Liquids And Their Applications In The Extraction/Separation Of Biomolecules

The analysis of biomolecules is of great significance to life science investigations and clinic diagnoses.In the analysis of real biological samples,biomolecules tend to be in matrix components and must be separated effectively and selectively.Solid phase extraction is the most commonly used method in separation and purification technology.As a new type of solid phase extractant,immobilized ionic liquids attract more attentions in this area.However,in the practical analysis process,the immobilization efficiency of ionic liquid is not high which causes low separation and purification efficiency.Meanwhile,it is difficult to ensure the complete coverage of the surface by ionic liquid in the immobilization process which causes limited selectivity for subsequent separation and purification.Polymeric ionic liquids(PILs)as polymers are generally solid materials at room temperature with functional groups of ionic liquid moiety.The emerging of PILs provides an effective solution for the problems of immobilized ionic liquid in the separation and purification technology.In this paper,PILs are introduced into solid phase extraction system.The present thesis focuses on the application of PILs as solid phase extractant for developing selective extraction/separation of biomolecules such as DNA,protein and curcuminoid.More details are summarized in the following:(1)A novel PIL,poly(1-vinyl-3-(2-methoxy-2-oxyl ethyl)imidazolium)hexafluorophosphate,is prepared via W/O emulsion polymerization.A fast DNA isolation protocol is thus developed with the PIL as solid phase extractant.Rapid ion-exchange between the anionic moieties of PIL and DNA is demonstrated facilitating the exchange equilibrium to be reached within 1 min and not affected by the variation of pH values.The PIL exhibits a high capacity of 190.7 μg mg-1 for DNA adsorption under optimal conditions.The retained DNA could be readily recovered with 1.0 mol L-1 NaCl as stripping reagent,giving rise to a recovery of ca.80.7%.Finally,the as synthesized PIL is used for the selective separation and purification of plasmid DNA from E.coli cell culture,demonstrating that plasmid DNA extracted by PIL has no difference with that achieved by a commercial Plasmid Miniprep Kit in quality but a higher extraction quantity.(2)A novel polymeric ionic liquid,poly(3-n-dodecyl-1-vinylimidazolium)bromide(Poly(C12vim)Br),is prepared via solution polymerization.The Poly(C12vim)Br exhibits excellent adsorption performance toward hemoglobin(Hb)in the presence of other protein species.Mechanism investigation shows that the coordination is the driving force of Hb towards the surface of Poly(C12vim)Br.The variation of ionic strength poses virtually no effect on the adsorption and a maximum adsorption capacity of 205.4 mg g-1 is derived for Hb under the optimum adsorption conditions.Afterwards,a recovery of ca.86.3%could be achieved by sodium dodecyl sulfate.CD spectra of the recovered Hb indicate that the structure of Hb remains predominantly as a-helix.Finally,the Poly(C12vim)Br has been used for the selective separation and purification of Hb from human whole blood,and a pure Hb sample is obtained.(3)A novel crosslinked copolymeric ionic liquid(CCIL)is prepared via miniemulsion polymerization by using N-vinyl-3-(2-methoxy-2-oxyl ethyl)imidazolium chloride as monomer and 1,4-butanediyl-3,3’-bis-l-vinylimidazolium dibromide as crosslinker.The as synthesized CCIL is used as extractant to separate curcuminoids.It is feasible to facilitate curcuminoids adsorption or stripping from the extractant by simply regulating hydrogen bonding interaction and hydrophobic interaction in a short time.A maximum adsorption capacity of 108.7 μg mg-1 is achieved for curcumin.Finally,this method is successfully applied to the separation and detection of curcuminoid from curcuma longa linn by HPLC.