Plant-Mediated Synthesis of LaCe and LaNd co-doped ZnO Nanoparticles: Investigation of Structural, Optical, Antibacterial and Anticancer Properties

Abstract

In the present investigation, the pure ZnO and rare earth metal co-doped ZnO nanoparticles, namely LaCe-ZnO and LaNd-ZnO nanoparticles, were successfully synthesized through an eco-friendly green synthesis approach using Gymnema sylvestre leaf extract. The plant extract acted as both reducing and stabilizing agent due to the presence of various bioactive phytochemicals such as flavonoids, phenols, tannins, saponins, triterpenoids, glycosides, steroids and glycerides. This green synthesis method offers a simple, cost-effective and environmentally benign alternative to conventional physical and chemical synthesis routes. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), UV-Visible spectroscopy and photoluminescence (PL) techniques to investigate their structural, morphological, elemental and optical properties. The antibacterial activity of pure ZnO, LaCe-ZnO and LaNd-ZnO nanoparticles was evaluated against Gram-positive bacteria (Staphylococcus aureus and Streptococcus pneumoniae) and Gram-negative bacteria (Klebsiella pneumoniae, Shigella dysenteriae, Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris) using the well diffusion method. Among the synthesized samples, LaCe-ZnO nanoparticles exhibited enhanced antibacterial activity compared with pure ZnO and LaNd-ZnO nanoparticles. Furthermore, in vitro cytotoxicity studies were carried out using A498 human kidney carcinoma cells and normal Vero kidney cells. The results revealed that LaCe-ZnO nanoparticles showed significant cytotoxic activity against A498 cancer cells with improved biological performance.