Plant-mediated silver nanoparticles from leaf extract of Dolichandra unguis-cati: Synthesis, antibacterial activity and cytotoxicity

Abstract

The use of plant-mediated synthesis of nanoparticles has gained attention as a simple and economical approach for the development of antimicrobial and cytotoxic nanomaterials. The biological activities of silver nanoparticles (AgNPs) synthesised using Dolichandra unguis-cati (Cat’s claw) remain insufficiently explored. This study aimed to synthesise and characterise AgNPs using an aqueous leaf extract of D. unguis-cati and to evaluate their antibacterial and preliminary cytotoxic activities. The formation of AgNPs was initially confirmed by a visible colour change of the reaction mixture from pale green to dark brown. Characterisation using UV-visible spectroscopy revealed a surface plasmon resonance peak at 415 nm after 24 hr of incubation. Transmission electron microscopy (TEM) showed the presence of spherical nanoparticles with sizes ranging from 5–20 nm. scanning electron microscopy (SEM) showed polygonal surface morphology and particle aggregation, while the TEM supported the polycrystalline nature of the AgNPs. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of silver (Ag) through a sharp Ag peak. Antibacterial activity evaluated by agar well diffusion assay showed an inhibition zone of 13 ± 0.58 mm at 1 mg/mL against Staphylococcus aureus and 11 ± 0.29 mm at 1 mg/mL for Escherichia coli. Furthermore, the Allium cepa mitotic index and human erythrocyte abnormality assays revealed cytotoxic and genotoxic effects, indicating apoptosis-like cell death. The present study provides a basis for further investigation of their potential biomedical applications.