Brown seaweed-mediated biosynthesis of gold nanoparticles

In the present study, we investigated biosynthesis of gold nanoparticles using the extracts of brown seaweed, Turbinaria ornata. The formation of gold nanoparticles was characterized using the UV-Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The synthesized gold nanoparticles showed distinct surface plasmon peaks at 525 nm and also the color of the reaction mixture gradually changed from brown to ruby red. Comparing the FTIR spectra of seaweed extract and synthesized gold nanoparticles, significant changes were observed in phenolic groups, alkynes, amide and esters. The XRD analysis showed intense peaks corresponding to (111), (200), (220), (311) and (222) Bragg’s reflection based on the face centered cubic structure of gold nanoparticles. Elemental gold was also confirmed by the EDX analysis. The SEM images illustrate that all the gold nanoparticles were well separated and there were no aggregations. Gold nanoparticles showed spherical morphology with average particle size of 7 – 11 nm.