Biological synthesis of metal nanoparticles

The development of techniques for the controlled synthesis of nanoparticles of well-defined size, shape and composition, to be used in the biomedical field and areas such as optics and electronics, is a big challenge. The use of the highly structured physical and biosynthetic activities of microbial cells for the synthesis of nanosized materials has recently emerged as a novel approach for the synthesis of metal nanoparticles. A number of different organisms, including bacteria, yeast and fungi, were screened for their ability to produce gold nanoparticles and examples of results demonstrating the formation of gold nanoparticles of different sizes and shapes are presented. The cellular mechanism leading to the reduction of the gold ions and formation of gold nanoparticles is not well understood and therefore the potential to manipulate key parameters, which control growth and other cellular activities, to achieve controlled size and shape of the nanoparticles was investigated. The results provided some insight as to which parameters may impact on the cellular mechanism involved in the reduction of gold ions and formation of gold nanoparticles. (C) 2006 Elsevier B.V. All rights reserved.