Study On The Preparation Of Uniform-Sized Silicon-Oil Emulsion And Chitosan Nano-Microspheres By Membrane Emulsification Technique

In recent years, emulsion has been widely used in various fields including food, cosmetics, medicine and other fields. The studies on the biodegradable polymer nano-microspheres have drawn much more attention in the biomedicine field. There are many methods to be used to prepare emulsion, including high-speed stator homogenization, mechanical stirring or ultrasonic emulsification. However, these methods exist some disadvantages such as the high energy consumption, the low produce efficiency, the large particle size, the broad size distribution and the poor repeatability. The un-uniform sizes of droplets would result in coalescence of emulsions, and further lead to phase separation between oil and water phase. These would lead to some limitations in many applications, such as destructive metamorphism and the low utilization ratio of nutritional components in food additives. As drug delivery, the un-uniform sizes of nano-microspheres also lead to the poor repeatability of drug delivery, the difficulty of control in drug release rate and the low bioavailability of drug in vivo. Therefore, the uniform-sized of emulsion and nano-microspheres is very important to obtain favorable applications.In order to prepare uniform-sized and size-controllable emulsion and nano-microspheres, membrane emulsification technique has been developed. Membrane emulsification technique has been widely applied in the fields of food, cosmetic, medicine, bioseparation and other fields because by this method uniform-sized and size-controllable emulsion can be easily obtained. As drug carrier, uniform-sized nano-microspheres by membrane emulsification technique display favorable characteristics, such as high encapsulation efficiency and well stability. Other advantages of membrane emulsification technique include low energy consumption, mild preparation conditions, which are suitable for encapsulation of bioactive substances. In this study, uniform-sized silicone emulsion and chitosan nano-microspheres were prepared by novel membrane emulsification technique, which will be used in the cosmetic and drug carrier, respectively.The dissertation is divided into two parts. The first part focused on the preparation of uniform-sized and controllable silicone emulsion by direct membrane emulsification technique. Several factors that influenced emulsion stability during the emulsification process were investigated, such as silicon-oil viscosity, emulsifier types, volume ratio of oil phase to water phase, concentration of emulsifier in water phase and storage temperature. Emulsions with different sizes were also successfully prepared by choosing the membrane with different pore size. The second part focused on the preparation of uniform-sized chitosan nano-microspheres by premix membrane emulsification technique. Several factors played key roles in obtaining chitosan nano-microparticles with narrow size distribution, including the amount of emulsifier in oil phase, the composition of oil phase, the concentration of chitosan, the ratio of water to oil phase, the transmembrane pressure and number of passes and so on. By optimizing preparation conditions, the uniform-sized chitosan nano-microspheres from 300nm to 1.7μm were successfully prepared by premix membrane emulsification technique. Premix membrane emulsification technique is a potential method to prepare other drug carriers with uniform size.