Study On The Preparation Of Responsive Microcapsules Based On Pickering Emulsion Via SPG Membrane Emulsification

Environmental stimuli-responsive microcapsules could adjust the release rate of encapsulated drug molecules according to the environmental conditions,avoiding the burst release of drug and thus enhancing the utilization rate of drugs.Compared to normal emulsions,Pickering emulsions are stabilized by solid particles other than surfactants,exhibiting low toxicity.Moreover,Pickering emulsions,as thermodynamic stable systems,are much stable than normal emulsions.We fabricated novel pHresponsive biocompatible microcapsules loading ibuprofen by using oil-in-water(O/W)type Pickering emulsion as template which was stabilized by chitosan(CS)-tripolyphosphate(TPP)nanoparticles(NPs).The study composed 3 parts as follows.First,CS-TPP NPs were synthesized using ion coagulation method.The effects of pH value,CS concentration,and mass ratio of CS to TPP on the size distribution of CSTPP NPs were investigated,based on which the preparation process was optimized.Second,the as prepared CS-TPP NPs was used to prepare O/W type Pickering emulsion by using SPG membrane emulsification.The effects of oil phase,pore size of SPG membrane,and trans-membrane pressure on size distribution of emulsion droplets were investigated.The optimized condition of SPG membrane emulsification process was obtained.Third,the microcapsule was prepared by solvent evaporation method using the o/w Pickering emulsion as template and ibuprofen as model drug.Poly(lactic-coglycolic acid)(PLGA)was introduced to realize the pH response property.The preparation conditions of microcapsules such as PLGA concentration and CS concentration were optimized.Finally,the in vitro releasing behavior of microcapsules at different pH conditions was determined.The cumulative release rate of drug carrier microcapsule was 74% in alkaline environment(pH=7.4)and 26% in acidic environment(pH=5)in 47 h of releasing period,which indicated that it had good pH responsibility.Consequently,the pH-responsive drug carrier microcapsules and the preparation method developed in this study may have potential applications in pharmacy field.