Research On Zein Microparticle Formation With Different Preparation Techniques

Natural biological materials have extensive applications in industries closely related to daily life such as food,pharmaceutics,cosmetics and agriculture.Zein is a water insoluble plant protein which has advantages of easy extraction,low cost,unique solubility,good biocompatibility and biodegradability and low toxicity and safety(GRAS)In this thesis,the dissolution characteristics of zein were studied using different techniques to prepare microparticles with good dispersibility,regular morphology and controlled particle size.These preparation techniques were further compared and analyzed to provide data and guidance for subsequent micronization of zein.First,zein microparticles were prepared via anti-solvent method freeze-drying.Effects of zein concentration,agitation rate,temperature,pH and different preparation methods on the morphology and particle size of zein were investigated.The results show that when temperature = 10 ?,stirring rate =150 rpm and zein concentration = 3%,zein microparticles with narrow particle size distribution(?400 nm),good sphericity and thermostability are obtained.This thesis also explored the preparation of zein microparticles by supercritical fluid assisted atomization with an enhanced mixer(SAA-HCM).Effects of specific experimental conditions including mixer temperature and pressure,precipitator temperature,solution concentration and ethanol percentage on particle morphology and size were investigated.The results show that the optimal conditions to prepare zein microparticles are:mixer pressure ?9.0 MPa,mixer temperature = 50 ?,settler temperature = 60 ?,zein concentration = 20 g·L-1 and the ratio of ethanol in solvent = 80%,The obtained microparticles have spherical morphology,good dispersibility and controllable particle size,and the average particle diameter is?3 ?m.Moreover,VD3-loaded composite microparticles were prepared by SAA-HCM.In addition,zein microparticles were prepared and obtained by secondary phase separation vacuum-drying.The pretreatment methods of zein solution were discussed,and the effects of primary phase separation and secondary phase separation and solution concentration on the morphology and particle size of zein were analyzed.The results show that the prepared zein microparticles with relatively small particle size(?200 nm)can be obtained when zein concentration = 3%.It is further verified that the preparation of microparticles after secondary phase separation is feasible.Finally,zein microparticles prepared from these different processes were compared.The results show that different preparation methods can be used to produce zein nanoparticles with different morphology.The particle size prepared by SAA-HCM is under micrometer level,and the particle size obtained from vacuum-drying study is smaller than that prepared by SAA-HCM.In summary,the unique solubility of zein can be applied in obtaining different particle size and morphology of zein microparticles by different preparation methods which has unique advantages in the application of drug and nutrient delivery systems.