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Biogenic synthesis of gold nanoparticles have been accomplished using dried biomass of two high altitude lichen species, collected from the alpine region of Eastern Himalaya in Arunachal Pradesh state of North East India, without addition of any external reducing or stabilizing chemicals. The nanoparticles were characterised by UV–visible, FT-IR spectroscopy, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). The as-obtained gold nanoparticles showed surface plasmon resonance (SPR) band at ~535 nm. The XRD study furnished evidence for the formation of face-centered cubic structure of gold nanomaterials. The nanoparticles produced with Acroscyphus sp. consisted of multiply twinned quasi-spherical and prismatic shapes while those accessed with Sticta sp. are exclusively multiply twinned. The biomatrix loaded gold nanomaterial exhibited pronounced antioxidant activity. [ABSTRACT FROM AUTHOR]

Abstract: Biosynthesis of gold nanoparticles has been achieved via reduction of an aqueous chloroauric acid solution with dried biomass of a freshwater epilithic green alga, Prasiola crispa, collected from a high altitude river ecosystem in Arunachal Pradesh state, India. The synthesized nanoparticles were characterized by UV–visible, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, and DLS studies. The UV–visible spectrum of the synthesized gold nanoparticles showed a surface plasmon resonance (SPR) around 535nm after 12h. The powder XRD pattern furnished evidence for the formation of face-centered cubic structure of gold having average crystallite size 9.8nm. The TEM images showed the nanoparticles to be nearly spherical in shape with sizes in the range of 5–25nm. [Copyright &y& Elsevier]