药剂学实验-Preparation of microcapsules 微囊.docVIP

Preparation of microcapsules Abstract Microcapsules are minute capsules of solid drugs or liquid drugs, its diameters are 0.01~200μm, encapsulated by polymer. In the experiment, sulfamerazine microcapsules are prepared by complex coacervation, the shell thickness is gelatin-acacia microcapsules. Key words microcapsule; complex coacervation; microencapsulation; gelatin Introduction Microencapsulation is an effective method to wrap liquid and/or solid material, known as core material by microcapsules and has potential extensive applications in fields of cosmetics, pesticides, pharmaceutical and medical applications, foods, biology, catalysis, carbonless copying paper and many other areas. Fig1. Microcapsules [3] Microcapsules are minute capsules of solid drugs or liquid drugs, its diameters are 0.01~200μm, encapsulated by polymer. After microencapsulated, drug can be sustained-released, enhance its stability, mask its unfavorable flavor and taste, reduce its irritation to gastrointestinal tract, decrease matching taboo of multiple medicine, improve its fluidity and compressibility of drugs and make liquid drug into solid. According to clinical demanding, microcapsules can be prepared into powders, capsules, tablets, injections and ointments etc. Fig2. Optical microscopy image of microcapsule Complex coacervation was described as a two-step process with spontaneous aggregation owing to the interaction of the oppositely charged polyelectrolyte, followed by rearrangement of these aggregates into coacervate phase, a polymer-rich super concentrated solution remaining in equilibrium with the dilute phase. The process of complex coacervation together with the properties of the resulted microcapsules can be influenced by many physicochemical parameters such as pH, charge density, type of ions, ratio of polyelectrolyte and ionic strength especially. Although complexes of proteins and strong polyelectrolyte tend to form precipitates or solid-like structures, it is reported tha