Plant extract reduced and stabilized gold Nanoparticles as model particles for foliar application of fertilizers

Abstract

Foliar application of nanofertilizers is currently regarded as a promising alternative to conventional soil fertilization. For successful development of nanofertilizers, firstly, a better understanding of interactions of nanoparticles with the leaf surface is needed. In the framework of this study a globally available cereal grain Hordeum Vulgare (barley) was chosen as model plant. Gold nanoparticles (Au NPs) were chosen as model particles for foliar application. Two synthesis methods were used: established photoreduction with citric acid and phytochemical synthesis using Aegopodium Podagraria (ground elder) extract. In both cases the reducing agent was acting also as surface stabilizer. Au NPs formation was confirmed by UV-VIS spectroscopy. To our knowledge it is the first time A. Podagraria extract was used for Au NPs synthesis. The morphology of the produced particles was characterized by transmission electron microscopy (TEM). The interaction of Au NPs with the adaxial side of barley leaves was studied by low-vacuum scanning electron microscopy (SEM). It was established that citrate stabilized Au NPs agglomerates evenly distribute in droplet-leaf contact areas avoiding stomates. Plant extract stabilized Au NPs form a film in the contact areas and accumulate on all leaf partsstomates, trichomes and lamina. It was shown that Au NPs produced via green phytochemical synthesis have improved interaction with the leaf surface of barley.