Laboratório de Nanobiotecnologia (LNANO), Embrapa Recursos Genéticos e Biotecnologia, Brasília, Brazil.
Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, Brazil.
J Sci Food Agric. 2019 Jul;99(9):4248-4259. doi: 10.1002/jsfa.9656. Epub 2019 Mar 22.
Silver nanoparticles (AgNPs), particularly those entrapped in polymeric nanosystems, have arisen as options for managing plant bacterial diseases. Among the biopolymers useful for the entrapment of AgNPs, chitosan is promising because of its low cost, good biocompatibility, antimicrobial properties and biodegradability. The present study aimed: (i) to greenly-synthesize AgNPs using different concentrations of aqueous extract of tomato leaves followed by entrapment of AgNPs with chitosan (CH-AgNPs); (ii) to characterize the optical, structural and biological properties of the nanosystems produced; (iii) to evaluate the antimicrobial activities of AgNPs and nanomaterials; and (iv) to assess the effectiveness of AgNPs and nanomaterials for controlling tomato bacterial wilt caused by Ralstonia solanacearum.
Spherical and oval AgNPs had incipient colloidal instability, although the concentration of the tomato leaf extract influenced both size (< 87 nm) and the polydispersity index. Nanomaterials (< 271 nm in size) were characterized by a highly stable matrix of chitosan containing polydisperse AgNPs. Free AgNPs and CH-AgNPs were stable for up to 30 days, with no significant alteration in physicochemical parameters. The AgNPs and nanomaterials had antibacterial activity and decreased bacterial growth at micromolar concentrations after 48 h. Morphological changes in R. solanacearum cells were observed after treatment with CH-AgNPs. The application of CH-AgNPs at 256 µmol L reduced the incidence of bacterial wilt in a partially resistant tomato genotype but not in the susceptible line.
Greenly-synthesized chitosan-derived nanomaterials containing AgNPs produced with leaf extracts from their own species appear to comprise a promising and sustainable alternative in an integrated management approach aiming to reduce the yield losses caused by bacterial wilt. © 2019 Society of Chemical Industry.
银纳米粒子（AgNPs），特别是那些被包埋在聚合物纳米系统中的粒子，已经成为治疗植物细菌性疾病的选择之一。在用于包埋 AgNPs 的生物聚合物中，壳聚糖很有前景，因为它成本低、生物相容性好、具有抗菌性能和可生物降解性。本研究旨在：（i）使用不同浓度的番茄叶水提物绿色合成 AgNPs，然后用壳聚糖（CH-AgNPs）包埋 AgNPs；（ii）表征所制备的纳米系统的光学、结构和生物学性质；（iii）评估 AgNPs 和纳米材料的抗菌活性；（iv）评估 AgNPs 和纳米材料对防治由茄青枯假单胞菌引起的番茄青枯病的效果。
球形和椭圆形 AgNPs 具有初始胶体不稳定性，尽管番茄叶提取物的浓度影响尺寸（<87nm）和多分散指数。纳米材料（<271nm 大小）的特征是具有包含多分散 AgNPs 的壳聚糖高度稳定的基质。游离 AgNPs 和 CH-AgNPs 在长达 30 天内稳定，理化参数无显著变化。AgNPs 和纳米材料在微摩尔浓度下具有抗菌活性，并在 48 小时后降低细菌生长。用 CH-AgNPs 处理后，观察到茄青枯假单胞菌细胞形态发生变化。在 256μmol L 浓度下应用 CH-AgNPs 可降低部分抗性番茄品种细菌性萎蔫的发病率，但对敏感品系无效。
用自身物种的叶片提取物绿色合成的壳聚糖衍生纳米材料中含有 AgNPs，似乎是一种有前途的可持续替代方法，可用于综合管理方法，以减少由细菌性萎蔫引起的产量损失。© 2019 化学工业协会。
