Positively-charged glycopolymer@AgNPs nanocomposites with exceptionally narrow size distribution and boosted...

Fungal diseases caused by Colletotrichum spp. severely threaten global agricultural productivity. Silver nanoparticles (AgNPs) offer potent antifungal activity, but their practical use is limited by instability, aggregation, and potential toxicity. This study aims to develop a safe, stable, and highly effective antifungal agent of carbohydrate-derived positively-charged glycopolymer-stabilized AgNPs (PGM@AgNPs) nanocomposites.

PGM@AgNPs exhibited an exceptionally narrow size distribution (7.41 ± 4.27 nm). The nanocomposite with the highest positive charge density (m/n = 2:1) achieved almost 100% inhibition of Colletotrichum fructicola spore germination at 8 μg mL^-1, significantly outperforming naked AgNPs in inhibiting mycelial growth and cicada wing penetration. On pears, mangoes, and kiwifruits, PGM@AgNPs reduced anthracnose lesion sizes by 46-70%. Transcriptomic analysis revealed that the antifungal mechanism involves inducing oxidative stress, disrupting cellular integrity, and triggering autophagic cell death. Moreover, PGM@AgNPs showed negligible hemolysis and low cytotoxicity toward L929 cells and zebrafish.

The carbohydrate-derived PGM@AgNPs combine superior stability, enhanced antifungal efficacy, and favorable preliminary biocompatibility. By effectively alleviating anthracnose symptoms in postharvest fruits, these nanocomposites represent a promising, environmentally friendly alternative to chemical pesticides for sustainable agricultural disease management. © 2026 Society of Chemical Industry.