Matras Ewelina, Gorczyca Anna, Przemieniecki Sebastian Wojciech, Oćwieja Magdalena
Department of Microbiology and Biomonitoring, Faculty of Agriculture and Economics, University of Agriculture in Kraków, Mickiewicz Ave. 21, 31-120, Kraków, Poland.
Department of Entomology, Phytopathology and Molecular Diagnostics, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 17, 10-720, Olsztyn, Poland.
Sci Rep. 2022 Oct 27;12(1):18046. doi: 10.1038/s41598-022-22659-2.
Silver nanoparticles (AgNPs) exhibit unusual biocidal properties thanks to which they find a wide range of applications in diverse fields of science and industry. Numerous research studies have been devoted to the bactericidal properties of AgNPs while less attention has been focused on their fungicidal activity. Our studies were therefore oriented toward determining the impact of AgNPs characterized by different physicochemical properties on Fusarium avenaceum and Fusarium equiseti. The main hypothesis assumed that the fungicidal properties of AgNPs characterized by comparable morphology can be shaped by stabilizing agent molecules adsorbed on nanoparticle surfaces. Two types of AgNPs were prepared by the reduction of silver ions with sodium borohydride (SB) in the presence of trisodium citrate (TC) or cysteamine hydrochloride (CH). Both types of AgNPs exhibited a quasi-spherical shape. Citrate-stabilized AgNPs (TCSB-AgNPs) of an average size of 15 ± 4 nm were negatively charged. Smaller (12 ± 4 nm), cysteamine-capped AgNPs (CHSB-AgNPs) were characterized by a positive surface charge and higher silver ion release profile. The phytopathogens were exposed to the AgNPs in three doses equal to 2.5, 5 and 10 mg L over 24 and 240 h. Additionally, the impact of silver ions delivered in the form of silver nitrate and the stabilizing agents of AgNPs on the fungi was also investigated. The response of phytopathogens to these treatments was evaluated by determining mycelial growth, sporulation and changes in the cell morphology. The results of our studies showed that CHSB-AgNPs, especially at a concentration of 10 mg L, strongly limited the vegetative mycelium growth of both species for short and long treatment times. The cell imaging revealed that CHSB-AgNPs damaged the conidia membranes and penetrated into the cells, while TCSB-AgNPs were deposited on their surface. The fungistatic (lethal) effect was demonstrated only for silver ions at the highest concentration for the F. equiseti species in the 240 h treatment. The number of spores of both Fusarium species was significantly reduced independently of the type of silver compounds used. Generally, it was found that the positively charged CHSB-AgNPs were more fungicidal than negatively charged TCSB-AgNPs. Thereby, it was established that the stabilizing agents of AgNPs and surface charge play a crucial role in the shaping of their fungicidal properties.
银纳米颗粒（AgNPs）具有独特的杀菌性能，因此在科学和工业的各个领域都有广泛应用。众多研究致力于AgNPs的杀菌性能，而对其杀真菌活性的关注较少。因此，我们的研究旨在确定具有不同物理化学性质的AgNPs对燕麦镰刀菌和木贼镰刀菌的影响。主要假设是，吸附在纳米颗粒表面的稳定剂分子可以塑造形态可比的AgNPs的杀真菌性能。通过在柠檬酸钠（TC）或盐酸半胱胺（CH）存在下用硼氢化钠（SB）还原银离子制备了两种类型的AgNPs。两种类型的AgNPs均呈现准球形。平均尺寸为15±4nm的柠檬酸盐稳定的AgNPs（TCSB-AgNPs）带负电荷。较小的（12±4nm）、半胱胺封端的AgNPs（CHSB-AgNPs）具有正表面电荷和更高的银离子释放率。在24小时和240小时内，将植物病原体暴露于三种剂量分别为2.5、5和10mg/L的AgNPs中。此外，还研究了以硝酸银形式提供的银离子和AgNPs的稳定剂对真菌的影响。通过测定菌丝生长、孢子形成和细胞形态变化来评估植物病原体对这些处理的反应。我们的研究结果表明，CHSB-AgNPs，尤其是在浓度为10mg/L时，在短期和长期处理中都强烈限制了两种菌株的营养菌丝生长。细胞成像显示，CHSB-AgNPs破坏了分生孢子膜并穿透细胞内部，而TCSB-AgNPs则沉积在其表面。在240小时处理中，仅对最高浓度的银离子表现出对木贼镰刀菌的抑菌（致死）作用。两种镰刀菌的孢子数量均显著减少，与所用银化合物的类型无关。一般来说，发现带正电荷的CHSB-AgNPs比带负电荷的TCSB-AgNPs更具杀真菌性。由此确定，AgNPs的稳定剂和表面电荷在其杀真菌性能的形成中起着关键作用。
