Production of Silver Nanoparticles from Seagrass Wastes by Green Synthesis and Determination of Their Antimicrobial Activities

Green synthesis of silver nanoparticles (AgNPs) has attracted great interest in the field of nanotechnology due to their antimicrobial and antioxidant properties in different applications. Posidonia leaves, known as seagrasses, detach from their stems during their life cycle and are carried by sea currents to form deposits on the shore. These biomass wastes hold the potential to be a source for nanoparticle synthesis. In this study, we present the synthesis of AgNPs using seagrass wastes without any chemical stabilizers or reducers. The aqueous extract is used as a reducing agent for synthesizing AgNPs at room temperature. The total phenolic and carbohydrate contents of extracts were analyzed using spectrophotometric methods. Ultraviolet-visible spectroscopy (UV–Vis), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to characterize the synthesized nanoparticles. The visual color change confirmed the formation of AgNPs. The UV-visible spectrophotometer showed an absorption peak at 420 nm. DLS measurements estimated the AgNPs size at approximately 50 nm. The AgNPs exhibited antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) microorganisms and antifungal activity against Candida glabrata. Antioxidant activities of the aqueous extract and AgNPs were also evaluated. This study highlights the successful use of a waste biological material in AgNPs production via green synthesis methods, showing promise across various fields.