Positively-charged glycopolymer@AgNPs nanocomposites with exceptionally narrow size distribution and boosted performance against fungi

BACKGROUND 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. RESULTS 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. CONCLUSION 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.