Mytilus edulis-mediated green synthesis of selenium nanoparticles with antimicrobial and molluscicidal applications.

This study investigated the bioactive profile of Mytilus edulis extract and its contribution to the green synthesis of selenium nanoparticles (ME-SeNPs), followed by comprehensive biological evaluation. HPLC analysis showed a high phenolic content dominated by gallic acid (61.25%) and chlorogenic acid (38.74%), indicating strong antioxidant potential. GC-MS profiling identified fifty compounds, mainly aromatic/heterocyclic constituents (37.37%) and lipid-derived constituents (37.04%), supporting diverse bioactivities and enabling nanoparticle biosynthesis through natural reducing and stabilizing agents. The successful formation of ME-SeNPs was confirmed by UV-Vis spectroscopy, evidenced by a surface plasmon resonance (SPR) peak at 260-350 nm and a clear visible color change. DLS measurements indicated moderate colloidal stability, with an average particle size of 292 nm and a zeta potential of - 33.13 mV. Morphological characterization by TEM and SEM revealed well-dispersed spherical nanoparticles with a size range of 35-65 nm. In addition, FTIR results verified the involvement of proteins and polysaccharides in the nanoparticle formation process. Biologically, ME-SeNPs exhibited significant antimicrobial activity. Testing against two standard bacterial strains demonstrated stronger inhibition of the Gram-negative bacterium Escherichia coli (MIC = 31.25 µg/mL) compared with the Gram-positive strain Staphylococcus aureus (MIC = 62.5 µg/mL). Regarding molluscicidal potential, the biogenic nanoparticles produced dose-dependent lethality against Biomphalaria alexandrina, with the median lethal concentration LC50 = 135.27 mg/L (95% CI 96.10-161.86 mg/L). The steep regression slope (1.18). Moreover, ME-SeNPs demonstrated dose-dependent molluscicidal effects in Biomphalaria alexandrina. However, sublethal exposure enhanced immune responses while concurrently inducing significant DNA damage.