INVESTIGATION OF POLYDL-LACTIDE-b-POLY(ETHYLENE GLYCOL)-b-POLYDL-LACTIDE MICROSPHERES CONTAINING PLASMID DNA

Abstract： PolyDL-lactide (PDLLA) and the block copolymer, polyDL-lactide-b-poly(ethylene glycol)-b-polyDL-lactide (PELA) were used as the microsphere matrix to encapsulate plasmid DNA. The PDLLA, PELA, pBR322-1oaded PDLLA and pBR322-1oaded PELA microspheres were prepared by solvent extraction method based on the formation of multiple w1/o/w2 emulsion. The microspheres were characterized by surface morphology, mean particle size, particle size distribution and loading efficiency. The integrity of DNA molecules after being extracted from microspheres was determined by agarose gel electrophoresis. The result suggested that plasmid DNA molecules could retain their integrity after being encapsulated by PELA. The PELA microspheres could prevent plasmid DNA from being digested by DNase. The in vitro degradation and release profiles of plasmid DNA-loaded microspheres were measured in pH = 7.4 buffer solution at 37℃. The in vitro degradation profiles of the microspheres were evaluated by the deterioration in microspheres surface morphology, the molecular weight reduction of polymer, the mass loss of microspheres, the changes of pH values of degradation medium, and the changes of particle size. The in vitro release profiles of the microspheres were assessed by measurement of the amount of DNA presented in the release medium at determined intervals. The release profiles were correlation with the degradation profiles. The release of plasmid DNA from PELA microspheres showed a similar biphasic trend, that is, an initial burst release was followed by a slow, but sustained release. 作 者： Yu LIU    Long Huang    Xiao-rong Qiao    Xian-mo Deng    Wen-xiang Jia    Xiao-hong Li   作者單位： Yu LIU,Xian-mo Deng,Xiao-hong Li(Chengdu Institute of Organic Chemistry, Academy of Sciences, Chengdu 610041, China)

Long Huang(Chengdu No. 1 Municipal Public Hospital, Chengdu 610016, China)

Xiao-rong Qiao(Nalysing and Testing Center, Si Chuan University, Chenghdu 610000, China)

Wen-xiang Jia(Huaxi Medicine School, Si Chuan University, Chengdu 610000, China) 

期 刊： 高分子科學(英文版)  ISTICSCI   Journal： CHINESE JOURNAL OF POLYMER SCIENCE  年，卷(期)： 2004, 22(3)  分類號：   Keywords： PolyDL-lactide-b-poly(ethylene glycol)-b-polyDL-lactide (PELA)    Microspheres    pBR322 DNA    Degradation    Release