Study On The Properties Of Amino Acid Surfactant Compounded System

Amino acid surfactants?AASs?have good biodegradability and environmental compatibility,as well as high safety,low irritation and low toxicity.Therefore,sodium lauroyl sarcosinate?SLS?,sodium lauroyl glycinate?SLG?and sodium lauroyl glutamate?SLGLU?were selected as research objects.The surface activity of AASs by different amino acid structures was studied.The interaction of different amino acid structures with biomacromolecules and ionic liquid surfactants was also studied.The surface tension of the AASs was measured by ring method at T=25?,critical surface tension(?_cmc),saturation adsorption(?_max),and minimum surface area per surfactant molecule(A_min)were calculated.The magnitude of critical micelle concentration?cmc?of the AASs was 10^-3 mol·L^-1 showed that AASs have good surface activity.The?_cmc of AASs is 30.42mN·m^-1,32.98 mN·m^-1,35.93 mN·m^-1 respectively,because of different head structure,the effects on different surface activity parameters are also different.?_max:SLG>SLS>SLGLU,A_min:SLGLU>SLS>SLG,pC₂₀:SLG>SLS>SLGLU.The foaming and wettability were measured.AASs have good foaming ability and foam stability.The surface tension of?-cyclodextrin??-CD?mixed with SLS,SLG and SLGLU was determined by drop volume method.It was found that?-CD could form a clathrate with surfactant.SLS and SLG formed a package with a inclusion ratio?AASs:?-CD?of 1:1 and2:1.The SLGLU formed a clathrate having an inclusion ratio of 1:1 and 1:2.The intrinsic fluorescence spectra of BSA-AASs and the fluorescence spectra of BSA-AASs-ANS were determined by fluorescence spectroscopy.It was found that BSA affected the micellization of surfactants.The binding isotherms of BSA-AASs interactions were obtained.It was found that with the increasing concentration of AASs,there were four characteristic regions in the interaction process:specific binding,non-cooperative binding,cooperative binding,and saturation.The relationship between the characteristic ultraviolet absorption wavelength of tyrosine?Tyr?,tryptophan?Trp?and phenylalanine?Phe?residues and the concentration of amino acid surfactants was obtained by Fourth-derivative UV absorption spectroscopy.Structural changes of the protein can be probed by monitoring shifts in the individual absorption peaks resolved by derivative analysis.Phenylbutazone,Ibuprofen and Hemin were selected as a binding marker for binding site I?Sudlow I?,binding site II?Sudlow II?and domain I,respectively.The binding sites of AASs interacting with BSA were Site I?Sudlow I?.The hydrodynamic radius?R_h?of mixed solutions of different concentrations of AASs without and with BSA was determined by dynamic and static light scattering,according to the change of R_h,it was found that there were two kinds of micelles distributed in the solution of 1¹0 nm and vesicles distributed in 70¹00 nm in two different cases.SLS and SLGLU can form a stable mixed system with[C₁₄Mim][Br],while SLG cannot form a stable system with[C₁₄Mim][Br];it is found that SLGLU and[C₁₄Mim][Br]was found synergistic effect,and the synergistic effect of SLS and[C₁₄Mim][Br]is not obvious.The rheology of SLS?SLGLU?and[C₁₄Mim][Br]mixed system was determined by HAAKE MARS ans HAAKE Viscostester IQ,including viscoelasticity,thixotropic,shear thinning and steady shear properties.The mixed system of SLS?SLGLU?and[C₁₄Mim][Br]is capable of forming stable micelles.The change of R_h in the complex system was investigated by dynamic static light scattering,and it was found that the aggregates formed by different mixed system configurations were also different in size.