Surface Modification And Hydrogel Embedding Of Bovine Serum Albumin Liposomes

In this work,bovine serum albumin(BSA)was used as a model protein drug to prepare nanoliposomes,and the preparation process was studied.By modifying the surface of the liposome and embedding the liposome in the three-dimensional network of the hydrogel,the structure of liposomes was stabilized and the drug slow-release performance of liposomes was improved.It provides experimental basis for the design and development of functional food and protein pharmaceutical preparations with high bioavailability and convenience.The main findings are as follows:(1)The bovine serum albumin liposomes(BSA-Lip)were prepared by reverse evaporation method with bovine serum albumin as a model protein drug.Single factor test was used to investigate the effect of mass ratio of lecithin to sitosterol,the concentration of bovine serum albumin,the volume ratio of organic phase to internal aqueous phase,and the ultrasonic time on the encapsulation efficiency of bovine serum albumin liposome.Box-Behnken response surface method(BBD)was then consequently used to optimize the preparation process of bovine serum albumin liposome.The results showed that the optimal experimental conditions were 3.58:1 mass ratio of lecithin to sitosterol,8.71 mg/m L of the concentration of bovine serum albumin solution,2.68: 1 of the volume ratio of organic phase to internal water phase,and 3 min of the ultrasonic time.Under this model,three parallel experiments were carried out,and the encapsulation rate of the obtained liposomes of bovine serum albumin was about 26.31%.The average particle size of bovine serum albumin liposomes was 206.2 nm,the potential was-30.3m V,and the PDI was 0.26.Transmission electron microscopy observations of liposomes showed that the bovine serum albumin liposomes were spherical.All of these results indicate that the preparation of liposomes was successful.(2)BSA-Lip was coated with chitosan(CH-BSA-Lip)in order to improve the stability of phospholipid bilayer membrane.It was found that the particle size of BSA-Lip increased after being coated with chitosan and the surface potential changed from negative charge to positive charge due to the electrostatic interaction between liposomes and chitosan.After chitosan coating,the encapsulation efficiency of liposomes also increased due to the interaction between positively charged chitosan and negatively charged BSA.Fourier transform infrared spectroscopy analysis confirmed that BSA was encapsulated into liposomes and chitosan was successfully coated on the surface of liposomes.Transmission electron microscopy showed that the particles were nanosized and spherical.The physical stability and in vitro digestion stability of liposomes were examined by observing the changes of particle size and potential.It was found that chitosan coating enhanced the stability of liposomes significantly.The in vitro release profile of CH-BSA-Lip possessed a slow release behavior,and the non-Fickian transport was the dominant release mechanism.(3)To study the controlled release of liposome-associated drugs entrapped in the p H-sensitive hydrogels,liposomes were embedded inside the hydrogel prepared with pineapple peel carboxymethyl cellulose(PCMC)and sodium alginate(SA).The Scanning electron microscopy(SEM)and Fourier transforms infrared spectroscopy(FIRT)characterizations showed the successful embedment of the prepared liposomes inside the hydrogel accompanied with change of the hydrogel in crystal structure while thermal stability.Swelling studies showed that the weight ratio of PCMC to SA has a significant influence on the swelling properties of the prepared hydrogels,and the introduction of the liposomes reduced the equilibrium swelling rate of the hydrogel.The swelling dynamic mechanism of the prepared hydrogels could be explained well by Fickian diffusion and Schott's pseudo-second-order models.In addition,the p H sensitivity study showed that the equilibrium swelling rate of the prepared hydrogel increased with the increase of p H value.In vitro release studies showed a more slowly sustained release of BSA from the prepared liposomal hydrogel composites compared with neat liposomes or neat hydrogels alone,and the cumulative amount of BSA released within 72 h was 22.2% released at p H1.2,much slower than 46.7% at p H7.2.