Study On The Properties Of Imidazolium Ionic Liquid Surfactants And Its Interaction With Proteins

As a new surfactant,ionic liquid surfactant has attracted more and more attention.It has dual characteristics of ionic liquid and surfactant.Therefore,it is of great significance to study the properties of ionic liquid surfactants,especially the interaction between ionic liquid surfactants and proteins in food,biology and other fields.The content of this paper is divided into three parts:1 Two kinds of imidazole ionic liquid surfactants[C_nmim]DCA and[C_nmim]SCN（n=10,12,14）were synthesized by ion exchange method.Their structures were characterized by ¹H NMR and ¹³C NMR,and their surface tension,conductivity and dynamic light scattering（DLS）were studied.[C_nmim]DCA and[C_nmim]SCN with the same carbon chain have lowerγ_cmc than[C_nmim]Br and higher surface activity than traditional cationic surfactants.DLS studies show that[C_nmim]DCA and[C_nmim]SCN exhibit different particle size distributions due to different anion volumes.2 The interaction between ionic liquid surfactants and bovine serum albumin（BSA）was studied by means of surface tension,conductivity,zeta potential,ultraviolet-visible spectroscopy,fluorescence spectroscopy and DLS.The results show that the interaction between ionic liquid surfactant and BSA is closely related to the concentration of ionic liquid surfactant.When ionic liquid surfactant is in the low concentration region,the electrostatic interaction is the main mode of action.The addition of ionic liquid surfactant protects the secondary structure of BSA;when ionic liquid surfactant is in high concentration,the electrostatic interaction is the main mode of action.In the region,hydrophobic interaction becomes the main mode of action.The secondary structure of BSA is destroyed and denatured by the addition of ionic liquid surfactants.From the DLS data,it can be seen that the particle size of BSA changed from 4.6 and 100 nm to 1160 nm with the increasing concentration of ionic liquid surfactant.Ionic liquid surfactants quench BSA fluorescence statically by influencing tryptophan residue microenvironment.3 The interaction between ionic liquid surfactant and gelatin was studied by means of conductivity,fluorescence spectrum and DLS.The results show that the interaction between gelatin and ionic liquid surfactant can be divided into the following parts.There are both positive and negative charged parts in gelatin molecule,while ionic liquid surfactant has positive charge.Therefore,when ionic liquid surfactant is in a lower concentration region,electrostatic interaction is the main mode of action,and electrostatic attraction leads to it.Molecular chain shrinkage,from the perspective of DLS data,shows that the particle size decreases;with the increasing concentration,hydrophobic interaction becomes the main mode of action,hydrogen bond breakage,gelatin molecular chain tertiary structure is destroyed.Ionic liquid surfactants and gelatin form complex to affect tyrosine residues and thus change the fluorescence intensity of gelatin.