堆型艾美耳球虫3-1E重组质粒微球的制备及体外释放试验

Preparation and in vitro release of 3-1E recombinant plasmid microsphere of Eimeria acervulina

用聚乳酸羟基乙酸共聚物(PLGA)将鸡堆型艾美耳球虫重组表达质粒pcDNA3.1-3-1E包封,采用水包油包水(W/O/W)双重乳化方法制备pcDNA3-3-1E/PLGA微球。通过正交试验设计优化PLGA微球制备工艺,考察PLGA浓度、聚乙烯醇(PVA)浓度、超声功率、复乳搅拌时间对评价指标(即微球粒径大小、包封率、载药量)的影响,确定制备微球的最佳工艺条件。测定微球的形态、粒径、完整性、质粒DNA包封率、载药量和释放程度;进行体外模拟鸡胃液和肠液试验,观察微球体外释药效果。结果显示,当PLGA浓度为8%、PVA浓度为1.5%、超声功率为60W、复乳搅拌6h为微球制备的最佳工艺参数,在光镜下呈散在圆形,粒径小于12μm。微球的包封率、载药量分别为84.25%和4.46%,裸质粒与微球中质粒超螺旋比例差距不显著,这表明在包被过程中的超螺旋质粒未发生明显的降解。在模拟鸡的胃肠液累积释放试验中,它的累积释放能力依次为pH 3.0>pH 7.4,载药微球在模拟鸡的胃肠液中24h释放26.8%,模拟肠液中24h释放11.2%,30d时体外累积释放率为81.7%,表明微球具有一定的缓释效果。

The PLGA was used as a carrier and pcDNA3.1-3-1E was used as model drugs,the pcDNA 3-3-1E PLGA microballoons was prepared via W/O/W emulsification technique.The influences of different factors on microspheres quality were evaluated by orthogonal-designing method.Four factors were considered in the experiment,whichwere PLGA concentration,PVA concentration,ultrasonic power,stirring time of secondary emulsion,respectively.Three indexs were evaluated by microspheres quality,which were particle size,entrapment effciency,loading effciency.The form,particle diameter,plasmid DNA encapsulation efficiency,drug loadings and release behavior of microspheres were evaluated.The optimization parameters are 8%PLGA,1.5% PVA and 60 W for ultrasonicatin power,stirring time of secondary emulsion of 6 hours.Microspheres were white powders,globular,and the particle diameter is less than 12 μm when observed in the super-microscope.The envelope rate and drug loading capacity was 84.25% and 4.46%,respectively.Naked plasmid and microsphere plasmid super spiral proportion was not obvious,suggested that super spiral plasmid did not degradation after coated.In the experiment model,the acumulative release ability of stomach intestine fluid was pH 3.0pH 7.4 in turn,and microballoons acumulative release during 24 h in simulated gastric juice and intestinal fluid were 26.8% and 11.2%,respectively.30 d in intestinal fluid was 81.7%,suggested microspheres have slow releasing effect.