PLANT CELL BIOTECHNOLOGY AND MOLECULAR BIOLOGY

Green synthesis of metal oxide nanoparticles using plant extracts offers an eco-friendly and sustainable approach for developing effective photocatalysts for environmental remediation. The present study reports the green synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous fruit extract of Manilkara zapota as a reducing and stabilising agent, with zinc nitrate as the precursor salt. The synthesised nanoparticles were characterised using Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Analysis (EDX), and X-ray Diffraction (XRD). FT-IR analysis revealed the presence of hydroxyl, amine, carbonyl, and alkyl functional groups involved in nanoparticle formation and stabilisation. FESEM micrographs showed predominantly spherical nanoparticles with slight agglomeration and an average particle size of approximately 35 nm. EDX analysis confirmed the elemental composition of zinc and oxygen, while XRD patterns verified the crystalline wurtzite structure of ZnO with an average crystallite size of 26.99 nm. The antioxidant potential of the nanoparticles was evaluated using the DPPH free radical scavenging assay and demonstrated appreciable antioxidant activity. Furthermore, the photocatalytic performance of the ZnO nanoparticles was assessed using methylene blue dye as a model pollutant under xenon lamp irradiation. The nanoparticles exhibited significant dye degradation efficiency, with degradation increasing progressively with irradiation time. The enhanced photocatalytic activity was attributed to the nanoscale size, high surface area, and abundance of active catalytic sites. The study demonstrates that Manilkara zapota-mediated ZnO nanoparticles are environmentally friendly, cost-effective, and promising materials for wastewater treatment and environmental remediation applications.