Green Synthesis of ZnO Nanoflake Using <i>Tridax procumbens</i> as a Structural Directing Agent for Enhanced Antibacterial Activity

In this study, Tridax procumbens was utilized as a structural directing agent (SDA) to synthesize zinc oxide (ZnO) nanoflakes using a green method. The X-ray diffraction (XRD) analysis confirms the hexagonal unit cell structure which is characteristic of ZnO nanoflake with a crystallite size of 17.53 nm. High-resolution scanning electron microscopy (HRSEM) confirmed the formation of ZnO nanoflakes. The presence of Zn and O from the energy-dispersive X-ray (EDX) further affirms the successful pure synthesis of ZnO nanoparticles. The UV-vis absorption spectrum exhibits a distinct absorption band at 370 nm, indicative of ZnO nanoparticle absorption characteristics. Additionally, dynamic light scattering (DLS) reveals the particle size distribution of the ZnO nanoflake to be 45.65 nm. The Fourier transform infrared (FTIR) result indicates the presence of C═O, C─H, C─O─C and Zn─O. The antimicrobial activity of ZnO nanoflake was evaluated using the well diffusion method against pathogenic organisms such as Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa. The results demonstrated that as the concentration of the ZnO nanoflake increases, the antimicrobial activity increases. The toxicity of the ZnO nanoflake synthesized using T. procumbens was tested using brine shrimp assay, and the result indicates that the toxicity is concentration dependent. The median lethal concentration (LC50) values were calculated to be 99.81 µg/mL. The findings from this research suggest that the biogenic method offers several advantages, including ease of processing and using more economical reagents. Additionally, synthesized ZnO nanoflake is a potential agent for the treatment of illness caused by pathogens tested in this study.