Green Synthesis of an Alginate-Coated Silver Nanoparticle Shows High Antifungal Activity by Enhancing Its Cell Membrane Penetrating Ability

As a kind of promising nanopesticide, in contrast to traditional synthesis strategies, the application of a polysaccharide in silver nanoparticle preparation can improve its stability and avoid the usage of harmful substances. In this work, a two-step strategy for synthesizing silver nanoparticles (A-AgNPs) from aldehyde-modified sodium alginate (ASA) was introduced. The size of the A-AgNPs synthesized can be controlled from 6 to 40 nm with a high dispersibility in water. Furthermore, compared to naked AgNPs (n-AgNPs), the A-AgNPs showed improved broad-spectrum antimicroorganism activity. We found that the A-AgNPs mainly exerted their antifungal activity through the changing of cell membrane permeability and affecting the soluble protein synthesis, destruction of DNA structure, and inhibition of DNA replication. Meanwhile, the A-AgNPs showed no inhibition of rice and N. benthamiana seed germination. Considering its high biocompatibility and the highly efficient antimicroorganism activity, A-AgNPs can be potentially applied in plant protection science research.