Synthesis of Lawsonia inermis-encased silver–copper bimetallic nanoparticles with antioxidant, antibacterial, and cytotoxic activity

The extract of the medicinal plant Lawsonia inermis, known as henna, was employed to synthesize silver–copper bimetallic nanoparticles (Ag–Cu NPs) in a unique, efficient, and cost-effective method. The shape, size, and structural features of synthesized Ag–Cu NPs were determined by ultra–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffractometer, field emission scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy methods. The rod-shaped Ag–Cu nanoparticles, averaging 41.66 ± 17.18 nm in size, synthesized from L. inermis, exhibited potent antioxidant activity by inhibiting 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) free radicals. They also displayed significant antibacterial effects against Pseudomonas aeruginosa (28 mm), Staphylococcus aureus (27 mm), Bacillus cereus (26 mm), and Escherichia coli (24 mm). Additionally, these nanoparticles induced notable morphological changes in cancer cells and demonstrated promising cytotoxicity against MDA-MB-231 tumor cells (IC50 = 37.40 µg·mL−1). However, they exhibited biotoxicity in Artemia nauplii, resulting in mortality rates ranging from 3.0% to 32.5%. The LC50 and LC90 values recorded for a 48-h exposure were 1.51 mg·L−1 and 2.59 mg·L−1, respectively. These findings highlight the potential application of L. inermis-derived Ag–Cu NPs in pharmacology and bio-nanomedicine.