【作者】 林春梅；

【导师】 崔海信；

【作者基本信息】 中国农业科学院 ， 生物物理学， 2009， 博士

【摘要】 农药是保证农业生产不可或缺的物质,农药亦是饱受诟病背负破坏环境、危害食品安全恶名的物质。合理的选择、正确的使用农药,是保证农作物丰产丰收、食品安全的关键源头。随着大量剧毒、高残化学农药逐渐被摒弃,开发和使用低毒、低残或无残留生物农药,成为缓解农药污染和保证人民健康的重要手段。阿维菌素作为当今世界使用量最大的生物农药之一,其常规乳油制剂、粉剂等,在防治蔬菜、经济作物害虫方面已有广泛的应用,然而其新剂型的开发缺乏突破,纳米技术的出现给这一问题的解决提供了很好的思路。无定形纳米SiO2、低分子量CTS作为新颖的杀虫、杀真菌、细菌、和防治植物病毒性病害的材料,在农业生产中已经得到一定应用。基于纳米SiO2、CTS在本领域及其他领域的研究成果,结合纳米载体材料在其他领域的研究成果,本论文开拓性的开展了将纳米SiO2进行表面改性并作为阿维菌素的载体以及水溶性CTS作为阿维菌素载体的研究。结果表明:⑴以硅酸钠为原料,通过溶胶-凝胶的方法得到纳米SiO2微粒,微粒外观呈白色粉末状;表面活性剂用量对微粒比表面积和平均孔径有一定影响;SEM及XRD分析结果,所制得的SiO2微粒为无定形非晶态,球形,平均粒径在50nm左右,聚集成团状;用不同种类的硅烷偶联剂对其进行改性后,SEM下显示,改性后的纳米SiO2分散性得到改善;IR分析表明,改性后的纳米SiO2出现有机吸收峰;在液体石蜡中呈现非常好的分散性能,在有机溶剂中对阿维菌素的吸附能力显著增强。⑵用纳米SiO2及改性后的纳米SiO2作为负载生物农药阿维菌素的载体,制备了纳米SiO2-阿维菌素载药体系;TEM下显示,载药体系粒径仍然为50nm左右;IR分析表明改性纳米SiO2与阿维菌素之间没有发生化学作用,只有物理吸附或弱的相互作用,对阿维菌素的化学性质不产生影响;随时间的延长,纳米SiO2、改性纳米SiO2吸附阿维菌素的量都呈增加趋势,但达到平衡时间不同;维菌素原药在30%乙醇介质中的溶出曲线较直、陡,没有明显的阿维菌素缓慢释放区间;纳米SiO2-阿维菌素纳米体系在30%乙醇介质中阿维菌素的溶出,前段时间释放浓度高,速度快,之后是缓慢释放,可持续几天的时间。⑶通过H2O2降解的方法,找到最佳的降解条件:1%H2O2、温度为60℃、水解时间1h,此时产物得率为47.8%;所得到的水溶性CTS与商品CTS进行IR结构对照分析,结果发现经这种方法降解后,CTS的原来结构不发生变化;所得到的水溶性CTS经紫外光谱法确定脱乙酰度为96.07%;所得到的水溶性CTS经粘度法测定其粘均分子量为5.20×104D。⑷利用自制的水溶性CTS,采用乳化-交联的方法,制备了水溶性CTS纳米载药体系;粒度分析仪考察不同相对分子质量的CTS形成的纳米粒的粒径,发现高分子量的CTS形成的纳米粒粒径大于低分子量CTS形成的纳米粒粒径;考察了不同质量比的水溶性CTS与TPP情况下,CTS载药纳米粒粒径、载药量、固体回收率的不同,结果发现,当二者质量比在6:1~7.5:1之间时,CTS纳米载药体系的超过80%的粒子粒径在100nm以下,载药量和固体回收率均超过30%,这时候体系在光照下的分解速率减缓、分散性、离心稳定性都为优级、对水温、不同水质水的适应能力强。本项目的研究工作证实,纳米SiO2/阿维菌素载药体系、CTS/阿维菌素纳米载药体系具有缓/控释、抗紫外线光照的能力,预示着这两种载药体系可以成为新型阿维菌素纳米制剂制备的友好环保材料。更多还原

【Abstract】 Pesticide is essential for farming, but it is criticized to be harmful to environment and food. Therefore the rational choice and proper use of pesticide are the most important issue in agriculture. Nowadays, because of the restrictive use of many chemical pesticides, biopesticides commence to play an important part in modern agriculture. The exploitation and application of biopesticides have been the ultimate means to lessen environmental pollution and ensure health of people. One of the most yield pesticides is Avermectics in the world, emulsifiable concentrates and dusts of Avermectics have been used for vegetables, economic crops, etc. but there is no better form of it. The Tappearance ofnanotechnology provided a good idea for this question. Amorphous nanosilica and the low molecular weight CTS are novel nanobiopesticides to be used controlling insects, bacteria, algae, viruses for plants and stockbreeding. Based on above mentioned research findings in agriculture and other fields, and the other findings of nanomaterials, we firstly conducted a study on the amorphous modified-nanosilica and low molecular weight CTS as carriers for Avermectics.Nanosilica is synthesized by sol-gel method, and its properties had been analyzed by the means of BET, SEM, TEM, XRD, IR, etc. the products take on white powder, the BET and BJH adsorption average pore diameter under the the different quantity of surfactant are different, the size of nanoparticles are about 50nm, roundness, amorphism, collective, After modified by silicone coupling agent nanosilica dispersed better than before.We preparated nanosilica-Avermectics system with nanosilica and modified nanosilica, the size of nanosilica-Avermectics system is about 50nm., Chemical reaction did not happen between Avermectics and nanosilica by IR except for thin interactions, Nanosilica absorbed the amount of Avermectics increased with the time until balance; Release profile of free avermectins was straight and abrupt in 30% ethanol, there was not obvious control realease line. Nanosilica-Avermectics system and modified nanosilica-Avermectics system released Avermectics quickly first, then slowly and continued for several days.The low molecular weight CTS was obtained by H2O2 decomposed method, 1%H2O2, 60℃,1h are the finest conditions. The structure of low molecular weight CTS is the same as the high molecular weight CTS as confirmed by IR. Deacetylation result of the low molecular weight CTS was 96.07% and the viscosity-average molecular weight of water-solubility CTS was 5.20×104D.The low molecular weight CTS nanoparticles system is prepared by emulsification-connection method. The size of nanoparticles which were synthesized by the high molecular weight CTS was larger than those which were synthesized by the low molecular weight CTS. Several conditions were reviewed, the results showed that the size of more than 80% particles were less than 100nm in this system, drug loadings and recovery rates were all more than 30%. The system could resist UV ray and had well dispersion, stability and suitable to different water.These results showed that nanosilica--Avermectics system and CTS nanomecidine carrier system were controlled realeased and UV ray resisted; Both of them could be used as environmental friendly materials for preparation of novel Avermectics forms.更多还原