The Aqueous Two-phase System Build Of Modified Tea Saponin And Salt And The Research On BSA Distribution Behavior

Traditional polymer aqueous two-phase system was an expensive and high viscosity system, so it is difficult to make industrialization. Now, a cheaper and lower viscosity aqueous two-phase system has become a hot topic. Based on traditional research, a new and cheap n-butyl tea saponin/salt aqueous two-phase system was found, the feature for n-butyl tea saponin (BTS)/salt aqueous two-phase system was researched, and the bovine serum albumin (BSA) distribution behavior in that system was explored.(1) The optimization synthesis condition of n-butyl of tea saponin and epoxypropyl tea saponin was got by-L16(45) orthogonal test. Under the condition of70℃,10%of mass fraction of catalyst, alkaline time1h, molar ratio1:8(tea saponin:bromine butane), reaction time6h, the highest yield was81.2%. Under the condition of70℃,20-30%of the mass fraction of catalyst, alkaline time1h, molar ratio1:8(tea saponin and epichlorohydrin), reaction time8h, the highest yield was80.8%.The structure of n-butyl tea saponin was characterized by DSC-TG analysis, UV and IR spectrum analysis. DSC-TG result showed that n-butyl tea saponin has weaker stability than tea tea saponin saponin, IR analysis result showed that n-butyl tea saponin has typical characteristic absorption at the peak of2957cm-1,2870cm-1,2924cm-1,2854cm-1,1375cm-1,1504cm-1,717cm-1, UV analysis result showed that it has obvious absorbance in201nm.(2) phase diagram of n-butyl tea saponin and salt (sodium sulfate, ammonium sulfate, sodium citrate) was made, the result showed that The result demonstrated in equilibrium curve that with concentration of n-butyl tea saponin increasing, the content of ammonium sulfate needed decrease, and the salting-out ability has the following order, sodium sulfate>sodium citrate>ammonium sulfate. The phase ratio(VT:VB) ranged from0.9-1.15in n-butyl tea saponin and ammonium sulfate system and0.65-1.05in n-butyl tea saponin and sodium citrate system. The tie line length (TLL) got larger with increase of n-butyl tea saponin that indicated that the difference in two phases got obvious and phase region got wider, the slope of tie line (STL) lowed with increase of n-butyl tea saponin, which reflected that the concentration of n-butyl tea saponin had great influence on the formation of ATPS. The phase formation of n-butyl tea saponin and salt (ammonium sulfate, sodium citrate) was influenced by temperature and pH, the result showed that the salt content decreased with temperature rising, and was the least at pH6.2. The top and bottom phase viscosity of n-butyl tea saponin and salt (ammonium sulfate, sodium citrate) was showed that, the upper and lower phase viscosity range of n-butyl tea saponin/salt (ammonium sulfate and sodium citrate) aqueous two-phase system was0.5-2.0mpa· s, lower than that in PEG2000/(ammonium sulfate and sodium citrate)system.(3) the effect of n-butyl tea saponin concentration on BSA-G250absorbance by UV spectrum method, it demonstrated that the interaction in n-butyl tea saponin and BSA-G250was much stronger with n-butyl tea saponin concentration rising (higher than1.0x10-3g·mL-1). The effect of n-butyl tea saponin content, pH, temperature on distribution behavior of BSA-G250showed that with increasing n-butyl tea saponin content, coefficient increased gradually; with increasing temperature, in n-butyl tea saponin/salt (ammonium sulfate and sodium citrate)system, the partition coefficient of aqueous two-phase system was gradually increasing, the optimal temperature was30℃. The distribution coefficient in ammonium sulfate system at the temperature was3.75and sodium citrate system was4.3; with the changing pH of the system, in the n-butyl tea saponin/salt (ammonium sulfate and sodium citrate) system, the maimum of6.2and8.5, respectively.