Biosynthesis of Silver Nanoparticles Using Ethanolic Extract of the Marine Alga Enteromorpha intestinalis and Evaluation of their Antibacterial Activity

The current study explored the use of the ethanolic extract of  Enteromorpha intestinalis to determine its capability to synthesize silver nanoparticles. The GC-mass technique was utilized to identify the active compounds in the algal ethanolic extract. The extract's potential in fabricating silver nanoparticles was tested, and their formation was inferred through the color change of the mixture from light green to dark brown. The synthesized nanoparticles were characterized using various techniques,  (FTIR) spectroscopy, a scanning electron microscope (SEM), and an energy-dispersive X-ray spectroscopy (EDX). In addition, they were analyzed using X-ray diffraction (XRD). The antibacterial effectiveness was tested through the agar well diffusion method. The GC-mass results showed that the ethanolic extract contained several active compounds, including n-hexadecanoic acid (37.40%), neophytadiene (11.08%), 9,12,15-octadecatrienoic acid, (Z, Z, Z)-(17.32%), and oleic acid (10.28%). A peak at 435nm in the UV-vis absorption spectrum confirmed the formation of silver nanoparticles. The XRD technique determined the crystalline nature of the silver nanoparticles, and SEM results showed that they had spherical shapes with sizes ranging between 47- 78nm. EDX analysis revealed that the synthesized silver nanoparticles comprised silver, carbon, oxygen, and chlorine. The efficacy of the synthesized silver nanoparticles was tested against four types of pathogenic bacteria, namely E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa,and Staphylococcus aureus. The results demonstrated that the silver nanoparticles had a significant inhibitory capability against these pathogens.