Biosynthesis of antibacterial gold nanoparticles using brown alga, Stoechospermum marginatum (kützing)

Biological synthesis of gold nanoparticles by brown alga, Stoechospermum marginatum biomasses through a green route was reported in this study. The formation of the gold nanoparticles was observed within 10 min. The properties of prepared nanoparticles were characterized by photoluminescence spectra, Fourier Transform Infrared Spectroscopy, scanning electron microscopy, Transmission Electron Microscopy, X-ray diffraction, particle size analysis and quantified by Wavelength Dispersive X-ray Fluorescence Spectrophotometer. The synthesized gold nanoparticles were found to be photoluminescent. The formation of gold nanoparticles was confirmed by the presence of an absorption peak at 550 nm using UV-visible spectrophotometer. TEM image revealed that most of the particles are spherical in shape and some are hexagonal and triangle with size ranged from 18.7 to 93.7 nm. The nanoparticles were crystalline in nature and it was confirmed by XRD pattern and the presence of elemental gold (45.92%) was confirmed by WD-XRF. From the FTIR measurements it is noticed that the reduction has been carried out by hydroxyl groups present in the diterpenoids of the brown seaweed. Furthermore the biologically synthesized gold nanoparticles were found to be effective against bacterial pathogens.