Yang C Y, Powell C A, Duan Y P, Zhang M Q
State Key Lab for Conversation and Utilization Subtropical Aro-Biological Resources, Guangxi University, Nanning, Guangxi, 530005, China, IRREC-IFAS, University of Florida, Fort Pierce, FL 34945, and Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
IRREC-IFAS, University of Florida, Fort Pierce, FL 34945.
Plant Dis. 2016 Dec;100(12):2448-2454. doi: 10.1094/PDIS-05-16-0600-RE. Epub 2016 Sep 30.
Nano-emulsion is a promising delivery system for increasing pesticide use and enhancing the therapeutic efficiency against pathogens. The pathogen Candidatus Liberibacter asiaticus (Las) that causes destructive citrus huanglongbing (HLB) resides in citrus phloem, which makes it difficult to treat with chemicals. Based on various physiochemical characteristics of oils, surfactants, and organic solvents, an oil-in-water (O/W) nano-emulsion formulation was developed and optimized to combat citrus HLB. The nano-emulsion was formulated through a spontaneous emulsification method for efficient delivery of ampicillin into the citrus phloem using bark application. The nano-emulsion that was prepared from Cremophor EL (viscous oil), acetone (water miscibility organic solvent), and Span 80/Tween 80 (surfactant) formed a small droplet size (17.33 ± 0.52 nm) and exhibited an improved absorption rate. Peak concentration was detected at 2 days posttreatment and the maximum concentration (C) and relative bioavailability (RBA) of ampicillin in HLB-affected citrus were 71.86 ± 35.38 ng/g and 267.25% ± 44.1%, respectively. The peak concentration of Amp appeared at 6 days posttreatment in the citrus trees that were treated with Amp alone and their C and RBA were 56.44 ± 32.59 ng/g and 100%, respectively. The same nano-emulsion was used to deliver five different antimicrobials to control citrus HLB through bark application. We found that the droplet size of the antimicrobials in the nano-emulsion was significantly reduced and the nano-emulsion also enhanced the therapeutic efficiency of validoxylamine A alone and in combination with actidione as well as sulfadimoethoxine sodium against Las. Therefore, this study provides an efficient bark application nano-emulsion formulation for citrus HLB control.
纳米乳剂是一种很有前景的给药系统，可用于提高农药利用率并增强对病原体的治疗效果。引起毁灭性柑橘黄龙病（HLB）的病原体亚洲韧皮杆菌（Ca. Liberibacter asiaticus，Las）存在于柑橘韧皮部中，这使得用化学药剂进行治疗变得困难。基于油、表面活性剂和有机溶剂的各种物理化学特性，开发并优化了一种水包油（O/W）纳米乳剂配方，以对抗柑橘黄龙病。该纳米乳剂通过自发乳化法制备，用于通过树皮施用将氨苄青霉素高效递送至柑橘韧皮部。由聚氧乙烯蓖麻油EL（粘性油）、丙酮（与水混溶的有机溶剂）和司盘80/吐温80（表面活性剂）制备的纳米乳剂形成了小液滴尺寸（17.33±0.52纳米），并表现出提高的吸收率。在处理后2天检测到峰值浓度，受黄龙病影响的柑橘中氨苄青霉素的最大浓度（C）和相对生物利用度（RBA）分别为71.86±35.38纳克/克和267.25%±44.1%。单独用氨苄青霉素处理的柑橘树中，氨苄青霉素的峰值浓度在处理后6天出现，其C和RBA分别为56.44±32.59纳克/克和100%。相同的纳米乳剂用于通过树皮施用递送五种不同的抗菌剂以控制柑橘黄龙病。我们发现纳米乳剂中抗菌剂的液滴尺寸显著减小，并且该纳米乳剂还提高了井冈霉素A单独使用以及与放线菌酮和磺胺二甲氧嘧啶钠联合使用时对Las的治疗效果。因此，本研究提供了一种用于控制柑橘黄龙病的高效树皮施用纳米乳剂配方。
