Biogenic synthesis and characterization of lanthanum oxide nanoparticles using citrus sinensis peel waste for antifungal applications in crop protection
Abstract
Introduction Green synthesis of metal oxide nanoparticles using agricultural waste offers a sustainable approach to developing alternative antifungal agents. This study investigated the potential of lanthanum oxide (La2O3) nanoparticles synthesized using Citrus sinensis peel extract as an eco-friendly antifungal agent against important phytopathogens. Methods La2O3 nanoparticles were synthesized using C. sinensis peel extract and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV–visible spectroscopy (UV–Vis), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX). Their antifungal activity was evaluated against Alternaria solani and Colletotrichum capsici at different concentrations and compared with the commercial fungicide SAAF. Results The synthesized La2O3 nanoparticles exhibited a crystalline cubic structure with characteristic physicochemical properties. FESEM analysis revealed irregular, flake-like to quasi-spherical particles, while EDX confirmed the presence of lanthanum, oxygen, and carbon. The nanoparticles demonstrated concentration-dependent antifungal activity against both pathogens. A. solani was more susceptible, with complete growth inhibition at 5 mg/mL, whereas inhibition of C. capsici reached 86.8% at 15 mg/mL. Complete suppression of sporulation was observed in La2O3-treated cultures. Against A. solani, La2O3 nanoparticles at 15 mg/mL, earlier than the commercial fungicide at 5 mg/mL. Discussion The findings demonstrate that C. sinensis peel-derived La2O3 nanoparticles possess substantial antifungal activity, particularly against A. solani. The combined physicochemical characterization and antifungal results support their potential as an eco-friendly biocontrol agent while highlighting the need for further optimization and evaluation against comparatively more resistant pathogens such as C. capsici.