ORIGINAL PAPER Biosynthesis of Silver Nanoparticles by Geotricum sp. Ali Jebali • Fatemeh Ramezani • Bahram Kazemi Received: 8 December 2010 / Published online: 31 March 2011 Ó Springer Science+Business Media, LLC 2011 Abstract Nanoparticles are usually 1–100 nm in each spatial dimension consid- ered as building blocks of the next generation of optoelectronics, electronics, and various chemical and biochemical sensors. In the synthesis of nanoparticles use of microorganisms emerges as an eco-friendly and exciting approach that reduce waste products (ultimately leading to atomically precise molecular manufacturing with zero waste); the use of nanomaterials as catalysts for greater efficiency in current manufacturing processes by minimizing or eliminating the use of toxic materials (green chemistry principles); the use of nanomaterials and nanodevices to reduce pollution (e.g. water and air filters); and the use of nanomaterials for more efficient alternative energy production (e.g. solar and fuel cells). Fungi have many advan- tages for nanoparticle synthesis compared with other organisms. In this study, Geotricum sp. found to successfully produce Ag nanoparticles. Geotricum sp. was grown in SDA (Sabro Dextrose Agar) medium at 25 ± 1 °C for 96 h. The mycelia were used to convert silver nitrate solution into nano-silver. Silver nanoparticles were synthesized using these fungi (Geotricum sp.) extracellularly. UV–VIS spec- troscopy, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy images shows the nanoparticle formation in the medium. Energy-dispersive X-ray spectroscopy (EDX) also confirmed that silver nanoparticles in the range of 30–50 nm were synthesized extracellularly. FTIR analyses confirmed the presence of amide (I) and (II) bands of protein as capping and stabilizing agent on the surface of nanoparticles. Keywords Silver Á Nanoparticle Á Biosynthesis Á Geotricum sp. A. Jebali Á F. Ramezani (&) Á B. Kazemi Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran e-mail: Fr_750@yahoo.com 123 J Clust Sci (2011) 22:225–232 DOI 10.1007/s10876-011-0375-5