Biofabrication of Silver Nanoparticles Using Green Seaweed: Characterisation and Antibacterial Evaluation

Abstract

This study investigates the Chaetomorpha antennina (CA) seaweed-mediated biosynthesis of silver nanoparticles (AgNPs). The synthesis process of silver nanoparticles was monitored over time with the help of an Ultraviolet-visible spectrophotometer and further characterisation studies were also performed. Differential Light Scattering (DLS) measurements revealed a mean particle size of approximately 103.5nm and a mean zeta potential value of -57.5mV for AgNPs. The spherical shape and size of the AgNPs were confirmed through High-Resolution Transmission Electron Microscopy (HR-TEM) imaging, while Energy Dispersive X-ray Spectroscopy (EDAX) analysis provided insights into the elemental composition. The concentration of AgNPs was estimated using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The antibacterial potential of AgNPs was evaluated against both gram-positive (Bacillus cereus, Staphylococcus aureus and Bacillus subtilis) and gram-negative bacterial strains (Klebsiella pneumoniae, Escherichia coli, Shigella dysentriae, Salmonella typhi, Pseudomonas aeruginosa and Proteus mirabilis) using the agar well diffusion method. From the results, AgNPs exhibited significant antibacterial activity against B. subtilis and S. typhi among all the tested concentration levels (25, 50, 75 and 100μl).