Green fabrication of zincite nanoparticles from underutilized biomass residue with their physicochemical characterization and antifungal analysis

This study presents a sustainable green synthesis method for zinc oxide nanoparticles (ZnO NPs) using Shorea robusta (SR) sawdust waste extract and evaluates their antifungal potential for wood protection. This eco-friendly approach is first of its kind to leverages the bioactive constituents of SR saw dust, chosen due to its high phenolic content, high abundancy but underutilized status in various plant and wood based industries, to facilitate nanoparticle formation without the use of toxic chemical reagents. Physicochemical characterization showed an extract yield of 17.00 ± 1.2% with high phenolic content (356.16 ± 3.1 mg gallic acid equivalent/g extract) and a ZnO NP yield of 30.84 ± 1.8%. X-ray diffraction (XRD) confirmed the formation of highly crystalline wurtzite ZnO with an average crystallite size of 28 nm. UV-Vis spectroscopy revealed an absorption band at 368 nm, slightly blue-shifted compared to bulk ZnO (~ 377 nm), indicating plant-assisted quantum confinement effects. Energy-dispersive X-ray diffraction (EDX) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed elemental purity and functional group interactions, respectively. Morphological investigations using SEM and TEM revealed well-dispersed, predominantly spherical ZnO NPs ranging from 20 to 40 nm, corroborating XRD findings. The biosynthesized ZnO NPs demonstrated strong antifungal activity against wood-decay fungi. The inhibition rates of Laetiporus sulphurous on 10 ppm, 30 ppm, and 50 ppm were 30.00 ± 1.2%, 62.86 ± 1.8%, 98.57 ± 0.5%, while that of Pycnoporus sanguineus were 21.54 ± 1.5%, 61.54 ± 1.3%, 96.92 ± 0.5%, respectively. This eco-friendly, low-cost approach offers an effective alternative to chemical fungicides in wood preservation, highlighting the potential of plant-based nanomaterials for sustainable industrial and biomedical applications.