Eco‐Friendly Synthesis of Silver and Selenium Nanoparticles Using <i>Lavandula angustifolia Drujba</i> Extract and Evaluation of Their Antibacterial and Cytotoxic Properties

ABSTRACT Silver (Ag) and selenium (Se) nanoparticles (NPs) have shown significant potential for biomedical applications due to their antimicrobial and anticancer properties, synthesized using a green approach. In this study, Lavandula angustifolia Drujba ( L.A. Drujba ) extract was used to synthesize AgNPs and SeNPs in an economical and environmentally friendly manner. The shape, stability, and average size of AgNPs and SeNPs were characterized using UV–vis spectroscopy, FTIR, TEM, SEM, and zeta potential analysis. Antimicrobial activity tests revealed that AgNPs exhibited higher efficacy against Staphylococcus aureus , MRSA and Pseudomonas aeruginosa , E. coli bacteria, with low MIC values. Additionally, AgNPs effectively inhibited quorum‐sensing pathways in P. aeruginosa , significantly reducing pyocyanin production, biofilm formation, and the expression of quorum‐sensing genes (LasI, LasR, RhlI, and RhlR). SeNPs demonstrated moderate biofilm inhibition but limited quorum‐sensing interference. Cytotoxicity studies using A549 lung cancer cells indicated that both AgNPs and SeNPs reduced cell viability and increased lactate dehydrogenase (LDH) level in a dose‐dependent manner, as confirmed by MTT and LDH assays, respectively. The obtained data underscore the potential of AgNPs and SeNPs synthesized from L.A. Drujba extract for antimicrobial and anticancer therapies.