Bio-green synthesis of Ag–GO, Au–GO and Ag–Au–GO nanocomposites using Azadirachta indica : its application in SERS and cell viability

Silver-graphene oxide, Gold–graphene oxide, Silver–Gold–graphene oxide nanocomposites were synthesized from Neem leaves ( Azadirachta indica ) extract using a bio-green one-pot method. The synthesized bio-green nanocomposites were characterized by UV–visible spectroscopy, x-ray diffractogram, transmission electron microscopy, x-ray photoelectron spectroscopy and Raman spectroscopy. The results indicated the decoration of ∼10 nm of silver, ∼20 nm of gold and ∼15 nm of silver–gold nanoparticles on a graphene oxide sheet. The synthesized nanocomposites showed enhancement in surface enhanced Raman spectroscopy with alizarin and also enhancement in cell viability of Chang liver cell lines which may be due to a synergetic effect of nanoparticles and graphene oxide. (paper)