Preparation Of Chinese Herb-loaded Natural (Synthetic) Polymer Microcapsules By Sonochemistry

Traditional Chinese herb has attracted extensive attention due to its good efficacy,low toxicity and low side effects.However,some active ingredient extracts are relatively sensitive to external influence and lose their effectiveness.Microcapsules,as a new type of drug delivery carrier,can encapsulate drugs and improve the bioavailability.After several decades of development,microcapsules can be prepared through many synthetic methods.But there are some problems to be solved: the complicated preparation process,the introduction of harmful substances,etc.Compared with conventional microencapsulation methods,sonochemistry is more simple,green and efficient.In this paper,the natural(synthetic)polymers/Astragalus membranaceus oil microcapsules were prepared by sonochemistry.Therein,bovine serum albumin(BSA),thiolated chitosan(TC)and polymethyl methacrylate(PMMA)were used as the shell materials and astragalus membranaceus oil(Ningxia Chinese herb extract)was used as the core material.BSA/AM microcapsules were prepared by sonochemistry.The effects of ultrasonic power,ultrasonic mode and ultrasonic time on synthetic reaction were investigated.The best ultrasonic synthesis conditions were determined by DLS,TEM,TG and UV,etc.They were: ultrasound amplitude 30%,ultrasound mode-pulse 2 s and halt 2 s alternately,ultrasound time 4 min.DLS results showed that the particle size was 573.1 nm and the PDI was small.TG results showed that the drug loading efficiency was about 75%.The hemolysis test showed that the microcapsules have no cytotoxicity at lower concentrations(less than 50 ?g/ml).TC/AM microcapsules were prepared by sonochemistry.The effects of thiol content and pH value on the synthetic reaction were investigated.The optimal degree of thiolation and pH value were determined through EDS,DLS and CLSM,etc.They were: the ratio of chitosan and thiolation reagent was 5.0,the pH value was 6.0.DLS results showed that the particle size was 962.4 nm.PMMA particles and PMMA/AM microcapsules were prepared by emulsionpolymerization initiated by ultrasonic irradiation.The effects of reactor size,ultrasonic amplitude and ultrasonic time on monomer conversion rate were investigated.The best synthesis conditions were determined by calculating the monomer conversion rate.They were: reactor volume 50 ml,ultrasound amplitude 100%,ultrasound time 30 min.DLS results showed that the particle size was 465.7 nm.TG results showed that the drug loading efficiency was about 84%.