Objective To prepare dual-targeted pH-sensitive DOX prodrug-microbubble complex and explore the characterization of complex with ultrasound as well as drug release in vitro . Methods Dual-targeted ligands ,cRGD and folate were conjugated with heparin using carbodiimide method ,and then the dual-targeted pH-sensitive DOX prodrug was synthesized by coupling DOX via a pH-sensitive hydrazone bond . The prodrug was combined with microbubbles to prepare complex by biotin-avidin system . The characterization of complex with/without ultrasound was investigated for size ,morphology and drug loaded capacity .In vitro drug release manner of complex with/without at different pH was analyzed . Results DOX content of the prodrug determined by UV Spectrophotometry was about 18 .9％ . Dynamic laser light scattering analysis( DLS) ,corresponding to transmission electron microscope( TEM ) findings ,revealed its inhomogeneous size distribution [ mean size ( 159 .7 ± 24 .5) nm and ( 1089 .0 ± 174 .9) nm ] . However ,the complex was dispersed into uniform fragment after ultrasound irradiation [ mean size ( 155 .9 ± 29 .8) nm , polymer dispersity index( PDI) 0 .22 ,Zeta potential - ( 20 .6 ± 3 .4) mV ] . The cumulative release rate of DOX from both complex and complex with ultrasound at pH 5 .0 were much faster than that at pH 7 .4 , displaying a pH-triggered release manner . Conclusions Dual-targeted pH-sensitive DOX prodrug-microbubble complex displays excellent drug release activity in acid environment . Uniform fragment and smaller particle size of complex could be achieved via ultrasound irradiation ,promoting DOX accumulation within tumor tissue and facilitating in vivo antitumor ability .%目的 构建一种双配体pH敏感阿霉素前药-微泡复合物,并研究其在超声辐照下的理化表征及体外释药特性.方法 碳二亚胺法将cRGD肽和叶酸配体连接到肝素上,阿霉素与肝素通过酸敏腙键连接,制备得双配体pH敏感阿霉素前药,再通过生物素-亲和素桥与微泡结合成复合物,检测超声辐照前后复合物的粒径变化 、 形态改变及不同pH介质中的释药特性.结果 紫外分光光度法测定双配体pH敏感阿霉素前药载药量约18.9％(DOX).动态光散射粒径分析(DLS)及透射电镜(TEM)检测发现双配体pH敏感阿霉素前药粒径分布不均一,出现纳米颗粒的聚集现象,粒径较多位于(159.7±24.5)nm处,小部分位于(1089.0±174.9)nm处.复合物经超声作用后粒径分布趋于均匀[平均直径(155.9±29.8)nm,聚合物分散性指数(PDI)0.22],Zeta电位为-(20.6±3.4)mV.体外释药实验表明双配体pH敏感阿霉素-微泡复合物具有良好的pH响应释放特性,在酸性介质(pH=5.0)释放效率要显著高于生理pH环境下(pH=7.4).结论 成功构建一种能在酸性环境下高效释药的双配体pH敏感阿霉素前药-微泡复合物,超声辐照可使复合物分散均匀 、 粒径减小,有助于药物进入肿瘤组织并在肿瘤酸性环境中释放,提高其体内抗肿瘤能力.
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