Abstract:

In order to reduce the loss of pesticides, a foliar affinity sustained-release microcapsules was designed. Polymethyl methacrylate (PMMA) was used to modify carboxymethyl cellulose (CMC), and then avermectin (AVM) was coated by self-assembly to form drug-loaded microcapsules (CMC-g-PMMA@AVM). The dopamine coating was then used to form affinity microcapsules (DA/CMC-g-PMMA@AVM). The structure and morphology were characterized by scanning electron microscopy, infrared spectroscopy and thermogravimetric analysis. The drug loading, leaf surface wetting and pH-responsive drug release properties were studied. The results showed that DA/CMC-g-PMMA@AVM was a spherical particle with an average particle size of 126nm. The coating of dopamine can effectively improve the drug loading performance of the microsphere and increase the encapsulation efficiency to 88.56%. The leaf affinity of AVM was enhanced and the leaf retention was increased by 30.56% relative to the emulsion of avermectin. The residual rate of AVM in AVM emulsion was only 14.03% after strong ultraviolet irradiation for 60min, while up to 59.55% in DA/CMC-g-PMMA@AVM. The drug release in the microcapsules had a pH response, and a burst release phenomenon occurred at pH=5. The release process conformd to the Weibull model and was controlled by Fick diffusion.

Key words: support, dopamine, avermectin, foliar affinity, stability, sustainability

摘要：

为减少农药流失，设计了一种叶面亲和型缓释微胶囊。以甲基丙烯酸甲酯（MMA）接枝改性羧甲基纤维素（CMC）得到羧甲基纤维素-聚甲基丙烯酸甲酯（CMC-g-PMMA），然后利用自组装负载阿维菌素（AVM）形成载药微胶囊（CMC-g-PMMA@AVM），通过多巴胺（DA）包覆提高CMC-g-PMMA@AVM的叶面亲和性。采用扫描电镜、红外光谱、热重分析等对其结构和形貌进行表征，研究了微胶囊的载药性能、叶面亲和性及响应释放性能。结果显示，DA/CMC-g-PMMA@AVM为平均粒径126nm的球形粒子，多巴胺的包覆可有效提高微胶囊的载药性能，包封率可达88.56%；增强AVM的叶面亲和性，使其叶面滞留量相对于阿维菌素水乳液提升30.56%；赋予AVM优异的抗紫外光分解性能，强紫外光照射60min后，由AVM水乳液中AVM的残留率14.03%提高到DA/CMC-g-PMMA@AVM中的59.55%。载药微胶囊中药物释放具有pH响应，在pH=5条件下出现爆释，药物释放过程符合Weibull模型，受Fick扩散控制。

关键词: 载体, 多巴胺, 阿维菌素, 叶面亲和, 稳定性, 可持续性