Preparation And Characterisation Of Squalene Microcapsules By Complex Coacervation

Squalene is a highly unsaturated linear triterpenoid with high bioactivity.It contains six unconjugated double bonds which are very unstable and easy to be oxidized,it leads to poor storage stability and low effective utilization.The microcapsules can be formed by encapsulating squalene with high molecular polymer to improve the stability of squalene,reduce the loss during storage,and increase the utilization rate.In this study,squalene microcapsules were prepared by complex coacervation using gelatin(GE)and gum arabic(GA)as wall material,squalene as core material and transglutaminase(TGase)as curing agent.Optical microscopy(OM),scanning electron microscopy(SEM),laser particle size analyzer,differential scanning calorimeter(DSC),thermogravimetric analyzer(TG)and Fourier transform infrared spectroscopy(FTIR)were used to characterize the structure and properties of squalene microcapsules.The oxidation stability,the release property and storage stability of microcapsules were investigated.The main results were as follows:(1)The effects of wall material composition,core /wall ratio,wall material concentration,p H value,stirring speed and emulsifying speed on the encapsulation efficiency,drug-loading rate and particle size of microcapsules were investigated and the preparation process was optimized by orthogonal experiment with encapsulation efficiency as the evaluation index.The optimal conditions were as follows: gelatin/gum arabic ratio of 1:1,core/wall ratio of 1:1,wall material concentration of 2%,p H value of3.6,stirring speed of 500 rpm and emulsifying speed of 10 000 rmp.Under this condition,the encapsulation efficiency was(68.2±1.5)%.(2)The structure and properties of squalene microcapsules were characterized.OM and SEM analysis showed that microcapsules had regular spherical mononuclear structure,uniform dispersion,good integrity and compactness.The average diameter of the microcapsules was(102.7±3.8)?m.The moisture content of the microcapsules was(3.81±1.30)%.FTIR analysis confirmed that squalene was successfully encapsulated in wall materials.DSC analysis showed that the glass transition temperature of microcapsules was 61.8 ?,which was far higher than room temperature(25 ?),indicating the storage stability of microcapsules was good.TG analysis demonstrated that wall materials played a certain role in protecting core material.The decomposition rate of squalene microcapsules was greatly reduced,and the thermal stability of squalene microcapsules was improved effectively.Oxidation stability study revealedthat microencapsulation could protect core material and the oxidation stability of squalene microcapsules was improved significantly.(3)The release property and storage stability of microcapsules were studied.The release test of microcapsules in simulated gastric juice and intestinal juice showed that release rate in intestinal juice was greater than that in gastric juice and the release rate was up to 83.8% in gastrointestinal juice.At 0~100 min,the release curve of microcapsules in simulated gastric juice and intestinal juice was basically in accordance with the first-order kinetic model,and at 100~300 min,the release curve was basically in accordance with the zero-order kinetic model.The study of storage stability showed that no light,no oxygen,low temperature and low humidity were beneficial to the storage of squalene and squalene microcapsules.Compared with ordinary squalene,the retention rate and stability of microencapsulated squalene were significantly improved.The retention rate of squalene in squalene microcapsules was still over 80% when stored under the condition of 25 ?,no light,no oxygen and low humidity for 60 days.