Process Parameters Investigation On The Preparation Of Microcapsules By Supercritical Impinging Stream Technology

Microencapsulation of active substance can take full advantage of its many important surface properties, such as controlled and sustained release, changing the surface affinity, conservation of biological activity, improving targeted drug delivery, as well as avoiding agglomeration of monodisperse particles. Based on the rapid expansion of supercritical fluid (RESS), combining with the advantage of fluidized bed technology and impinging stream technology, established a experimental platform of RESS-fluidized bed-impinging stream technology, in order to achieve the preparation of microcapsules and process analysis. The main contents and conclusions are as follows:(1) Poorly water-soluble drug NTD was chosen as core materials, biocompatible dispersing polymer PEG4000was chosen as wall material, EA was chosen as cosolvent. In addition, a water-soluble drug VC was chosen as core materials, biodegradable polymer PLLA was chosen as wall material, DCM was chosen cosolvent. Making full use of the established experimental platform and Preparation microcapsules of PEG4000/NTD and PLLA/VC.(2) Analysis of physical properties and phase composition of the experimental samples by DSC and XRD, as well as qualitative and quantitative analysis of surface morphology and particle size distribution by OM, SEM and LPSA. The results show that:Sample of microcapsules having a good sphericity and forming a more complete and uniform coating layer under specific operating conditions, with a narrow range of particle size distribution.(3) Established an analytical method of drug loading and accumulating ratio in vitro dissolution, measured by UV. The process parameters of the extraction pressure, extraction temperature, pre-expansion temperature, impinging distance and polymer concentration were investigated on the influence of drug loading, coating thickness and in vitro cumulative release characteristics. The results show that:the influence trend of extraction pressure, impinging distance and polymer concentration were more significant, while extraction temperature and pre-expansion temperature is not obvious. In vitro release rate of PEG4000/NTD microcapsules has been significantly improved, while PLLA/VC microcapsules has been controlled and sustained. (4) Established a experimental platform of flow field measurement, and investigated the process parameters of extraction pressure, extraction temperature and impinging distance on the influence of flow field characteristics in turbulent region by PIV technology. In order to provide a theoretical basis for research.