Li Yaping, Ogris Manfred, Pelisek Jaroslave, Röedl Wolfgang
Center of Drug Research, Department of Pharmacy, Ludwig-Maximilians-University, Butenandtstrasse 5-13, D-81377 Munich, Germany.
Int J Pharm. 2004 Jan 9;269(1):61-70. doi: 10.1016/j.ijpharm.2003.08.019.
The aims of this work were to determine the stability of DNA-calcium-phosphate coprecipitation (CaPi-DNA) against various conditions during double emulsification microencapsulation and assess the release and physicochemical characteristics of poly(D,L-lactide-co-glycolide) (PLGA) microparticles loading CaPi-DNA. CaPi-DNA prepared at pH 6.5 showed a good stability with over 60% CaPi-DNA remained after emulsification, but no more than 40% at pH 8.0. Polyvinyl alcohol (PVA, 1-5%) could make over 80% CaPi-DNA (pH 7.0) preserved after homogenization. The dichloromethane (DCM), mixture of DCM and ethyl acetate, ether and n-hexane (1:1) exhibited neglectable influence on CaPi-DNA under homogenization. PLGA had influenced on CaPi-DNA without any additional stabilizer, in particular, PLGA (75:25, 4%, w/v) demonstrated a profound damage with only about 10% of the original CaPi-DNA remained. PLGA microparticles loading CaPi-DNA were spherical in shape with size range of 2.0-5.0microm, and entrapment efficiency 30-50%. CaPi-DNA was found to increase the stability of pDNA in PLGA microparticles without losing its structure integrity. The release of CaPi-DNA from microparticles showed a low burst release (<7.5%) within 24h and following sustained release process. The amount of cumulated CaPi-DNA release over 30 days was: 17.6% for PLGA (lactide:glycolide=50:50), 27.3% for PLGA (65:35) and 44.8% for PLGA (75:25) microparticles, respectively. The encapsulation of CaPi-DNA in microparticles could significantly protect CaPi-DNA from degradation of nuclease with average over 80% of total DNA recovery. These results suggested that the encapsulation of CaPi-DNA in PLGA microparticles could improve stability of pDNA.
本研究的目的是确定在双乳化微囊化过程中，DNA-磷酸钙共沉淀（CaPi-DNA）在各种条件下的稳定性，并评估负载CaPi-DNA的聚（D，L-丙交酯-共-乙交酯）（PLGA）微粒的释放情况和理化特性。在pH 6.5条件下制备的CaPi-DNA具有良好的稳定性，乳化后仍有超过60%的CaPi-DNA残留，但在pH 8.0时残留量不超过40%。聚乙烯醇（PVA，1-5%）可使均质后超过80%的CaPi-DNA（pH 7.0）得以保留。二氯甲烷（DCM）、DCM与乙酸乙酯的混合物、乙醚和正己烷（1:1）在均质过程中对CaPi-DNA的影响可忽略不计。在没有任何额外稳定剂的情况下，PLGA对CaPi-DNA有影响，特别是PLGA（75:25，4%，w/v）对其造成了严重破坏，仅约10%的原始CaPi-DNA残留。负载CaPi-DNA的PLGA微粒呈球形，尺寸范围为2.0-5.0微米，包封率为30-50%。发现CaPi-DNA可提高pDNA在PLGA微粒中的稳定性，且不丧失其结构完整性。CaPi-DNA从微粒中的释放表现为在24小时内有较低的突释（<7.5%），随后为持续释放过程。30天内CaPi-DNA的累积释放量分别为：PLGA（丙交酯:乙交酯=50:50）为17.6%，PLGA（65:35）为27.3%，PLGA（75:25）微粒为44.8%。将CaPi-DNA包裹在微粒中可显著保护其免受核酸酶降解，总DNA回收率平均超过80%。这些结果表明，将CaPi-DNA包裹在PLGA微粒中可提高pDNA的稳定性。
