Biosynthesis of zinc oxide and silver/zinc oxide nanocompositesusing Kalanchoe pinnata leaf extracts for antibacterial and anticancer applications

Abstract

Green synthesis of metal and metal oxide nanoparticles has attracted considerable attention due to its eco-friendly nature and enhanced functional performance. Zinc oxide (ZnO) nanoparticles have been extensively explored; however, their efficiency is often limited by rapid charge recombination and moderate biological activity. The incorporation of silver (Ag) and the use of plant-mediated synthesis offer a promising strategy to overcome these limitations.In the present study, Ag–ZnO nanoparticles were synthesized via a green route using Kalanchoe pinnata leaf extract as a natural reducing and stabilizing agent. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Visible spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDAX). The biological activities were evaluated using standard antioxidant and antibacterial assays.XRD analysis confirmed the crystalline nature of ZnO with the successful incorporation of Ag, without the formation of secondary impurity phases. The FTIR spectra revealed the presence of phytochemical functional groups responsible for nanoparticle stabilization. SEM images demonstrated nearly spherical and well-dispersed nanoparticles, while EDAX analysis confirmed the elemental composition of Ag and Zn. UV–Visible spectroscopy indicated enhanced optical absorption due to Ag incorporation.The Ag–ZnO nanoparticles exhibited significantly improved antioxidant and antibacterial activities compared to pure ZnO, which can be attributed to the synergistic effect of Ag and bioactive phytochemical capping. This study demonstrates that Kalanchoe pinnata-mediated green synthesis effectively enhances the structural, optical, and biological performance of Ag–ZnO nanoparticles, highlighting their potential for eco-friendly biomedical applications.