Investigations On The Mass-transferring Behaviors Of Protein Between Aqueous/ionic Liquid Phases Using An Liquid-core Optical Waveguide System

As a kind of novel green solvent,ionic liquids(ILs)is merited with the features of mild nature,negligible vapor pressure,non-volatility and excellecent biocompatibility,and gain extensive applications in the extraction/purification of protein species recently.In present study,the mass-transferring behaviors of protein between aqueous and ILs phase are investigated with liquid-core optical waveguide technique,by using Hemoglobin as the protein model.The development of liquid-core waveguide technique is firstly introduced in this paper,and a brief reviews is also given to the applications of liquid core waveguide technique in the field of analytical chemistry.At the same time,the applications of ILs in the field of extraction/separation are summarized as well.In the experimental section,the liquid-core optical waveguide system is fabricated by using hydrophobic ILs(1-butly-3-methylimidazolium hexafluorophosphate(BmimPF6)and 1,3-two-butlyimidazolium hexafluorophosphate(BBimPF6)as the core,and the protein sample as one of cladding layer.The incident light is introduced into the waveguide system via an optical fiber,and then total internal reflections are formed at the aqueous/ILs interface,which assure the smoothly propagation of waveguided light in the ILs layer.The characteristics of monitored spectra should be governed by the adsorption of evanescence at the aqueous/ILs interface and the waveguided light in the ILs layer.The results indicate that the mass-transferring of Hemoglobin consist two dynamic procedures,i.e.,the accumulation of the protein at the aqueous/ILs interface interface and the extraction of the Hemoglobin molecules into the ILs phase.The mass-transferring behaviors of Hemoglobin molecule under different pH and concentration,and the effect of hydrophobicity are investigated.The results suggest that the mass-transferring of Hemoglobin from aqueous phase towards ILs phase is mainly driven by the coordination interaction between the heme group of protein and the cationic moiety of ILs,while the electrostatic interaction nearly pose any effect on the mass-transferring behaviors of Hemoglobin.At the same time,Hemoglobin molecules is prone to be extracted into a media of higher hydrophobicity.