Facile biosynthesis of zinc oxide nanoparticles (ZnO NPs) using Lupinus albus L (Gibto) seed extract for antibacterial and photocatalytic applications

This study aimed to synthesize zinc oxide nanoparticles (ZnO NPs) from Lupinus albus L. (white lupin) seed extract and investigate their photocatalytic and antibacterial applications. Phytochemical analysis of the seed extract revealed the presence of flavonoids, polysaccharides, alkaloids, and phenolic compounds. Three ZnO NP samples were prepared using different ratios of the seed extract and zinc nitrate and one sample without seed extract as a control. The nanoparticles were characterized using various techniques, and the average crystallite sizes were found to be in the range of 20.96–30.67 nm, exhibiting a hexagonal wurtzite structure. The photo catalytic activity of the ZnO NPs was evaluated by the degradation of malachite green dye under visible light. The results showed that ZnO NPs synthesized with the seed extract, particularly the 9:1 and 3:2 ratios, exhibited higher photocatalytic activity, with degradation efficiencies of 98 % and 97 %, respectively, compared to the ZnO NPs prepared without the extract (89 % degradation). The antibacterial activity of the ZnO NPs was assessed against four bacterial strains using the disc diffusion method. The ZnO NPs synthesized with the seed extract demonstrated the greatest activity against Klebsiella pneumonia, with an inhibition zone of 15 ± 0.58 mm, while the ZnO NPs without the extract showed lower antibacterial activity. In conclusion, the green synthesis of ZnO NPs using Lupinus albus L. seed extract is a promising approach for the development of materials with efficient photocatalytic and antibacterial properties.