负载乙蒜素的有机硅/壳聚糖复合乳液的制备及其对烟草青枯病的防治效果

Preparation of organosilicon/chitosan composite emulsion loaded with ethylicin and its control efficacy on tobacco bacterial wilt

为实现乙蒜素在作物表面的高效附着和缓慢释放,开展了负载乙蒜素的有机硅-壳聚糖高黏附缓释体系研究。由含氢硅油与丙烯酸发生硅氢加成反应制备有机硅乳液;借助疏水相互作用,实现乙蒜素与有机硅分子的均匀混合;最后经由壳聚糖氨基与有机硅乳液上羧基的静电组装,形成负载乙蒜素的有机硅/壳聚糖复合乳液。测定了复合乳液对烟草叶片的润湿性和黏附性、贮存稳定性、水合粒径、Zeta电位、微观结构,对乙蒜素的包封率和载药量,乙蒜素释放速率,复合乳液的抑菌活性以及对烟叶青枯病的防治效果。结果表明:负载乙蒜素的有机硅/壳聚糖复合乳液SA6@EC8为优选配方,其对烟草叶片的接触角为14.9o,表面张力为20.17 mN/m,在竖直烟草叶片表面延展良好,表现出良好的润湿性能和黏附性;复合乳液冷、热贮存14 d未见分层或沉淀,Zeta电位为+24.7 mV,平均水合粒径为3.17μm,平均干燥粒径为750 nm,颗粒在显微镜下呈单分散状态;复合乳液对乙蒜素的包封率和载药量分别达到94.7%和55.2%,其24、72和144 h乙蒜素累积释放率分别为55.4%、75.5%和82.3%,表现出先快后缓的控释特征;SA6@EC8乳液对大肠杆菌和青枯菌表现出优异的平板抑制活性,对田间烟草青枯病的相对防效也达到了38.5%;同时,在叶片发黄面积为10%以下时喷施SA6@EC8,发黄叶片可在施药5 d后返青;发黄面积达50%以上时喷施该乳液后,未观察到叶片返青。本研究成功开发了负载乙蒜素的有机硅-壳聚糖复合乳液,赋予乙蒜素制剂高黏附能力和缓释性能,实现了对烟草青枯病的良好防控,应用前景广阔。

In order to achieve efficient adhesion and slow release of ethylicin on the surface of crops,research was conducted on the organosilicon-chitosan high-adhesion sustained-release system loaded with ethylicin.The basic organosilicon emulsion is prepared by hydrosilylation of silicone oil containing hydrogen and acrylic acid.Ethylicin was uniformly mixed with organosilicon molecules through hydrophobic interactions.Finally,through the electrostatic assembly between chitosan amino groups and organosilicon carboxyl groups,the organosilicon/chitosan composite emulsion loaded with ethylicin was prepared.The leaf wetting and adhesion,stability,particle size,Zeta potential,microstructure,encapsulation efficiency,loading capacity,release rate,bacteriostatic activity,and the control effect on tobacco bacterial wilt of the composite emulsion were observed.The results showed that the organosilicon/chitosan composite emulsion SA6@EC8 loaded with ethylicin was the optimized formulation:the contact angle on tobacco leaf was 14.9ºand the surface tension was 20.17 mN/m,showing good wetting performance and good extension on the vertical tobacco leaf surfaces;no layering or precipitation was observed after cold and thermal storage for 14 days,with a Zeta potential of+24.7 mV,an average hydrated particle size of 3.17μm,an average dry particle size of 750 nm;the emulsion particles were monodisperse under a microscope;the encapsulation efficiency and loading capacity of the composite emulsion for ethylicin reached 94.7%and 55.2%,respectively,and the cumulative release rates of ethylicin at 24,72,and 144 h were 55.4%,75.5%,and 82.3%,respectively,exhibiting a fast-toslow controlled release characteristic.SA6@EC8 showed excellent plate inhibition activity against Escherichia coli and the pathogenic bacterium of tobacco bacterial wilt-Ralstonia solanacearum.Field trials showed that SA6@EC8 achieved a relative control efficacy of 38.5%against tobacco bacterial wilt.Meanwhile,it was found that spraying SA6@EC8 emulsion on tobacco leaves with a yellowing area of less than 10%makes the leaves turn green after 5 days.However,no such phenomenon was observed when the yellowing area exceeds 50%.In this study,a composite emulsion comprised of organosilicon and chitosan loaded with ethylicin,was successfully developed,which endowed this the ethylicin formulation with exceptional adhesive capability and sustained release performance,achieving good efficacy in preventing and managing bacterial wilt of tobacco,thereby presenting broad applications prospects.