Purpose: To evaluate a green process for the extracellular production of silver (Ag) nanoparticles synthesized and stabilized using Penicillium citrinum isolated from soil.
Methods: The pure colonies of Penicillium citrinum were cultured in Czapek dox broth. The supernatant of the broth was examined for the ability to produce silver nanoparticles. The reactions were performed in a dark compartment at 28 oC. After 24 h, the synthesized silver nanoparticles were filtered through a membrane filter (0.45 ƒÊ) and characterized by UV-visible spectroscopy, fluorescence spectroscopy, photon correlation spectroscopy (PCS), scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR) for particle size, shape and the presence of different functional groups in the nanoparticles.
Results: The silver nanoparticles formed were fairly uniform in size with a spherical shape and a Zaverage diameter of 109 nm. FTIR spectra revealed the presence of amide linkage groups which were also found in the fungal extract itself.
Conclusion: The current approach suggests that rapid synthesis of nanoparticles of silver nitrate would be suitable for developing a biological process for mass scale production of formulations.

Keywords: Green synthesis, Penicillium citrinum, silver nanoparticles.