Biogenic gold nanoparticles from the Actinomycete Gordonia amarae: Application in rapid sensing of copper ions

In recent years, biogenic nanoparticles have been used for a variety of applications. The role of gold nanoparticles (AuNPs) derived from a hitherto unreported Actinomycete isolate (Gordonia amarae) in sensing copper ions has been investigated in the current study. When the cell free supernatant (CFS) of G. amarae was incubated with 2 mM chloroauric acid (HAuCl4) at pH 10.0 and 90 °C for 20 min, a ruby red color was observed indicating the synthesis of gold nanoparticles. The nanoparticles showed a peak at 530 nm. X-ray Diffraction studies, Transmission Electron Microscope observations, Selected Area Energy Dispersion patterns and Energy Dispersive Spectra revealed the presence of 15-40 nm sized spherical and polycrystalline AuNPs. The bioinspired nanoparticles aggregated in the presence of cysteine (70 μM) and changed color from ruby red to purple. This aggregation was specifically inhibited in the presence of Copper (II) ions in the nanomolar range. These biogenic nanoparticles could be used for the specific detection of copper ions in aqueous solutions and spiked serum samples.