Stability Quality And Bioavailability Of Bovine-serum-albumin-dextran-lutein Nanoparticles

Lutein is a long-chain terpenoid compound with 40-carbon atoms,nine conjugated double bonds and two ionone rings.Lutein has strong antioxidant activity and can protect the retina,reduce cataract/night blindness and other physiological functions.It can only be supplemented by consuming animals and plants containing lutein.However,it is hard to dissolve in water,and it is easily degraded under the influence environmental factors.The bioavailability of lutein is low after oral administration.Therefore,how to improve the lutein’s water-solubility,absorption and utilization rate is an urgent problem to be solved.In this study,the graft product of BSA and dextran was used as the carrier of lutein.The embedding effect of BSA-dextran carrier on Lutein and the properties and functions of BSA-dextran-lutein were studied and analyzed.Firstly,the moist-heat maillard reaction conditions for the preparation of BSA-dextran graft products were optimized by single factor experiments（including protein concentration,substrate ratio,buffer pH value,time,temperature）and response surface method,and used SDS-PAGE electrophoresis,high performance liquid chromatography,infrared spectroscopy and fluorescence spectroscopy to inspect and characterize the molecular weight,purity,key groups and structure of the products;The functional properties of the products were examined by means of surface hydrophobicity,foamability and thermal stability.The results showed that when the concentration of BSA was 2.78mg/mL,the molar mass ratio of dextran to BSA was 6.89:1,the pH value of buffer solution was 8.5,the reaction time was 2.3 h,and the reaction temperature was 95℃,the emulsifying activity of the graft product was the highest,31.743 m²/g,the molecular weight was about 152 kDa,and the purity was 89.449%.Compared with BSA,FTIR analysis showed that the contents of alpha-helix and beta-fold decreased,the contents of beta-rotation angle and irregular curl increased,and the absorption peak of C-O bond was appended at 1000 cm^-1.Intrinsic fluorescence spectrum showed that tyrosine participated in the grafting reaction,the maximum absorption occurred blue shift,and the fluorescence intensity decreased.The surface hydrophobicity index was 58529,which increased by34904;the foamability was 41.6%,increased by 9.93%,and the foaming intensity decreased.The foam stability was 65.13%and increased by 13.88%.The thermal stability remained at 100.33%after 1 hour of water bath at 100℃.Compared with BSA（the thermal stability was only 47.88%after 1 hour of water bath at 70℃）,it has been improved.In addition,two kinds of nanoparticles were prepared by ethanol injection-high pressure homogenization:BSA-lutein and DBSA-lutein.The encapsulation efficiency of lutein was determined by organic solvent washing method combined with SDS solubilization method.The particle size,PDI value and Zeta potential of nanoparticles were calculated by dynamic light scattering method.the storage stability of the three particles（lutein,BSA-lutein and DBSA-lutein）was tested and compared.The results showed that the encapsulation efficiency of DBSA-lutein was 95.86%,the particle size was176.8±6.5 nm（PDI 0.176±0.07）,the Zeta potential was-30.5±0.6 mV,the encapsulation efficiency of BSA-lutein was 77.82%,the particle size was 166.7±8.6 nm（PDI 0.276±0.05）,and the Zeta potential was-18.6±1.0 mV.Compared with lutein,the storage stability of the two nanoparticles were improved significantly,and the encapsulation efficiency of DBSA-lutein was higher,the nanoparticles were more stable,and the storage stability were bette.Finally,the controlled-release characteristics of BSA-lutein and DBSA-lutein to lutein were studied by simulated gastrointestinal fluid digestion model in vitro.The results showed that BSA-lutein and DBSA-lutein could maintain relatively stable structure in simulated gastric fluid,and their cumulative release rates were very low（respectively8.69%and 6.07%）,which could protect lutein well.In simulated intestinal fluid,compound trypsin increased the particle size and PDI value of both and destroyed the structure of nanoparticles.Led to a higher cumulative release rate（respectively 40.18%and 24.57%）.Cholate promoted the disintegration of nanoparticles,accelerated the release of lutein and increased the bioavailability（respectively 51.5%and 72.5%）.