Mechanistic insights into antifungal and photocatalytic efficacy of green synthesized copper oxide nanoparticles: Experimental validation coupled with in silico modelling

Copper oxide nanoparticles (CuO NPs) are emerging as promising multifunctional agents for agriculture and environmental remediation. The present study involves the green synthesis of CuO NPs using Polyalthia longifolia leaf extract. The photo-catalytic and antifungal efficiency of CuO NPs were evaluated for degrading rhodamine B (RhB) dye and controlling Sclerotinia sclerotiorum on tomato. The photocatalytic degradation obtained almost 35% removal of RhB dye in the initial 10 minutes and eventually attained an overall 90.5% in 80 minutes using CuO NPs as a photo-catalyst. CuO NPs (25-500 ppm) significantly suppressed mycelial growth of S. sclerotiorum (3-62%) and minimized the pathogenic effects in tomato. It was observed that root-dip treatment with CuO NPs enhanced growth, photosynthetic pigments and fruit yield of tomato plants. The molecular docking analysis indicated a significant binding affinity between CuO NPs and key fungal proteins. The CuO NPs reacted with polygalacturonase and S. sclerotiorum agglutinin having a binding energy of -10.26 kcal/mol and -10.3 kcal/mol, respectively. The successful synthesis of CuO NPs was confirmed through comprehensive characterizations using Fourier transform-infrared spectroscopy, X-ray diffraction, high resolution-transmission electron microscopy, scanning electron microscopy-energy-dispersive X-ray, and UV-visible spectroscopy. GC-MS analysis identified 30 compounds in P. longifolia leaf extract that played a crucial role in CuO NPs synthesis. The eco-friendly synthesis and multifunctional properties of CuO NPs highlight their potential as sustainable agents for crop protection and environmental remediation. • Green-synthesized CuO NPs degrade ~90.5% RhB dye within 80 minutes. • CuO NPs strongly suppress S. sclerotiorum on tomato plants. • Root-dip CuO NP treatment boosts tomato growth, biomass, and yield. • Docking shows CuO NPs interact with key fungal proteins for antifungal action. • FTIR, XRD, TEM, SEM, EDX, UV-Vis confirm successful CuO NP synthesis.