Synthesis, characterization, and antifungal activity of chitosan–copper nanocomposites against crop pathogens

Chitosan–copper nanoparticles (CHT–Cu NPs) were synthesized using an ionic gelation approach and evaluated for their physicochemical properties and antifungal activity against major fungal pathogens of chickpea and citrus. For instance, “In recent years, nanotechnology-based formulations have emerged as promising strategy for sustainable disease management”. Dynamic light scattering analysis revealed uniformly sized nanoparticles (~150 nm) with low polydispersity and a positive surface charge (+22.2 mV). Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive X-ray analysis confirmed effective copper coordination, amorphous nanocomposite formation, and stable incorporation of copper within the chitosan matrix. The antifungal efficacy of CHT–Cu NPs was assessed in vitro against Colletotrichum ciceri , Fusarium ciceri , Rhizoctonia bataticola , Sclerotium rolfsii , and Colletotrichum gloeosporioides . The nanocomposites exhibited strong, concentration-dependent inhibition of mycelial growth. F. ciceri was highly sensitive, showing complete inhibition at all tested concentrations (≥100 µg mL − ¹). S. rolfsii and chickpea pathogens C. ciceri and R. bataticola were completely inhibited at concentrations 200 µg mL − ¹, 300 µg mL − ¹ and 300 µg mL − ¹, respectively, whereas C. gloeosporioides was comparatively less sensitive and required higher concentrations (≥400 µg mL − ¹) for complete suppression. In contrast, chitosan alone and copper sulfate showed only moderate antifungal activity. These findings demonstrate that CHT–Cu NPs possess broad-spectrum antifungal activity and superior efficacy compared to conventional fungicides, highlighting their potential as eco-compatible nanobiopesticides for sustainable management of fungal diseases in crop plants.