| In this research, yak butter microcapsule (MYB) was prepared by using maltdextrin (MD), sodium caseinate (CS), and whey protein concentrate (WPC) as wallmaterials. To explore the possibility of using microcapsulation technique forimproving the stability of YB, the possible mechanism for microcapsule formation,and the digestibility in vitro, the characteristics of MYB was analyzed. The effects ofrecipe composition, digestion model and a variety of digestive fluid composition onthe properties of MYB after digestion in simulated gastrointestinal (GI) fluids werealso investigated in details. This work would provide technical guide and theory basisfor developing a series of MYB suitable for various people and widening theutilization of this type microcapsule in further research.What’s more, to develop stable coix seed oil (CSO) carrier for targeted therapyof reticuloendothelial system, ethanol injection method and high-pressuremicrofluidization was used for preparation of CSO liposomes, the pharmacokineticsand tissue distribution of the carrier was analyzed. In addition, thermosensitivemagnetoliposomes containing CSO was also successfully prepared, magnetictargeting and temperature controlled release of the liposomes was verified though invitro release and anticancer experiments, for the purpose of provide a new strategy fortargeted and efficient treatment of malignant tumors.1. In this research, microcapsules containing Chinese yak butter (YB) wereprepared by spray drying technique using MD/WPC/CS as wall materials. Thephysiochemical properties, nutritional value, stability and in vitro digestion behaviorof MYB were analyzed. The results indicated that MYB were round-shaped particleswith good flow properties, high microencapsulation efficiency (MEE,97.4%) andprolonged shelf life. H-bonding interactions between protein and carbohydrateensured the integrity of the capsule wall. After rehydration, the reconstitutedemulsion was found to be uniform and stable. Results also suggested YB with morekinds of fatty acids and a ω-3/ω-6ratio higher than0.33was more nutritional forhuman consumption than commercial milk powder, and spray drying process had nearly no side effects on nutritional value of YB. In addition, the comparativeanalysis of leakage behavior after exposure to different simulated gastrointestinaltract (GIT) fluids indicated that YB could be efficiently leaked out of MYB except aratio bound to wall materials.2. In this research, four MYB of different wall composition (MD，MD+WPC，MD+CS，MD+WPC+CS) were prepared. The physiochemical properties and in vitrodigestion behavior of MYB as a function of time during digestion in SGF and SIFwere evaluated. The results indicated that all samples were relatively complete withnone bankrupted particles in the SEM photograph; particles of the MYB with MD asthe wall material was uneven, while that of MYB with MD and protein as wallmaterials was relatively uniform, and the MYB with MD+CS+WPC as wall exhibitedthe most uniform particle size distribution. The moisture contents of all samples were<5%, and was in the order MD+CS> MD+CS+WPC> MD+WPC> MD. The flowability of MYB with MD and protein as wall were better than that with only MD aswall material, the MYB with MD+WPC as wall was found exhibited the best flowability. The microencapsulation efficiency of MYB containing protein was all higherthan95%, and was also higher than that of ones with MD as wall material. Thedigestive behavior of MYB with MD+CS and MD+WPC as wall materials wasinvestigated, and the data suggested that more YB released after incubation in SIFthan in SGF. The digestion started earlier for MYB with MD+CS as wall than theMD+WPC MYB, while the latter is more easily to digest than the former.3. MYB with different YB added was prepared by spray drying method, theeffect of YB addition on the physiochemical properties of MYB, the influence ofpancreatin and bile salts digested behavior of the microcapsules were theninvestigated. The results indicated that microcapsules were hollow spheres withentrapped YB located in the wall materials, and the compactness and uniformity ofwall were affected by core addition. Higher core addition also resulted in lower MEE,although MEE of all samples was higher than90%. Low concentration of bile saltswould promote the hydrolysis of pancreatic enzyme to MYB wall materials, leadingto the released YB, whears high concentration bile salts would reduce the releasedYB due to emulsification of bile salts. The MYB with high YB added was more easily to be digested due to thin wall. The hydrolysis of protein increased withincreasing concentrations of added pancreatic enzyme and bile salts. The embeddingeffect of protein hydrolysis for released YB was mainly assigned to the hydrolysisfrom of CS and large molecular weight peptides of WPC. The bile salts concentrationhad no significant effect on the hydrolysis of CS, while the influence was significantfor that of WPC, and the degree of hydrolysis increased with the increase in bile salts.4. In this work, the effects of enzyme, pH and SGF pretreatment on the digestivebehavior of MYB with different wall were investigated. The results indicated thatmore free acid was determined in MYB after digestion in presence of variousenzymes at pH6.5than at pH7.5, and the presence of amylase inhibited the esterlysis.The emulsifying activity of WPC hydrolysate by typsin was stronger than that of CS,and WPC and its hydrolysate were easier to be absorbed by bile salts than CS and itshydrolysate, resulting in more FC released for MYB with MD+WPC as wallmaterials. Therefore microcapsule with MD+WPC as wall material is suitable for fastenergy needs, and the ones with MD+CS as wall material was more suitable for longtime energy needs. The hydrolysis of protein in MYB by pepsin during pre-exposureto SGF increased the chances of the combination of bile salts and emulsion interface,improving esterlysis of MYB during digestion in SIF and enhancing the formation ofnew type of O/W emulsion with smaller particle size. In this sense, pre-exposure toSGF is advantageous to the digestion of MYB.5. The physicochemical properties of CSO liposomes prepared by five differentmethods were evaluated for EE, particle size and in vitro release. The differentpreparation methods resulted in several types of vesicles with different properties.The type of vesicles was closely related to leakage pattern, which affected the in vitrorelease profiles. Ethanol injection method was the best choice for preparing safe andstable liposomes with small particle size, high MEE and controlled release. Theeffects of microfluidization process on the physiochemical properties of liposomesprepared by the method combined ethanol injection and high pressuremicrofluidization were then analyzed. The results suggested that as the pressureincreased MEE showed a varying extent of increase and particle size became smallerand homogeneous. The excellent particle was obtained when treated at160MPa for 2cycles, but too strong treatment exhibited adverse effect on the physicochemicalproperties of CSO liposomes.6. In this experiment, the pharmacokinetic of CSO liposomes prepared byethanol injection and high pressure microfluidization method was determined in SDrat after intragastric administration of liposomes. The results indicated that the T1/2αofliposomes was one half of that of microcapsule group, and T1/2of lipopsomes wasmuch higher than that of microcapsule group, AUC0-24of liposomes group was1.3times than that of microcapsule group. All the data suggest that the bioavailability ofCSO could be great improved after entrapment in liposomes. In addition, plasmaclearance rate of CSO microcapsule is1.65times that of the liposomes, while theapparent distribution volume of liposomes is1.46times that of the microcapsule,indicating that CSO carried by liposomes is widely distributed in organization, andcould be was more easily removed in the blood. In this case, coix seed oil liposomescould effectively reduce drug dosage, improve therapeutic index and reduce theadverse reaction when used in clinical applications.7. The tissue distribution of CSO liposomes after intragastric administration inrat was also investigated. The results indicated that the targeting efficiency (te), Cmaxand AUC of liposomes in reticuloendothelial system (liver, spleen, lung) was higherthan those in microcapsule group, whereas opposite result was found in kidney. Thissuggests that the liposome prepared by ethanol injection and high pressuremicrofluidization method was targeted for reticuloendothelial system, and could beused as a targeting carrier for the therapy of disease in reticuloendothelial system.8. In this research, PEG-Fe3O4was successfully prepared by coprecipitation. Theobtained nanoparticles exhibited superparamagnetism with uniform particles ofsmaller than20nm. Thermosensitive magnetoliposomes (TML) containing PEG-Fe3O4and CSO were then prepared with cholesterol and1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) by thin-film method. Encapsulation efficiency of CSO andPEG-Fe3O4, particle size, zeta potential and in vitro drug release were studied.More than80%of loaded CSO was released from TML within30min when theenvironmental temperature increased from37°C to42°C, while almost40%of thedrug was remained inside TML for up to24h at37°C. Furthermore, the MTT assay showed that the anticancer activity of TML showed significantly increased anticanceractivity for HepG2cell when exposed to an external constant magnetic field andheated to42°C compared to the absence of the magnetic field and heating. Therefore,the results in this study suggested that TML can archive a good magnetic targetingeffect and fast drug release in response to hyperthermia, which implies their greatpotential of application in cancer therapy. |
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