Biosynthesis of inorganic nanoparticles

Usually for the synthesis of nanomaterials a combination of approaches are used. The approaches may be melting and solidification processes, followed by thermo mechanical treatments, or solution/vacuum deposition and other growth processes. For the biological systems researchers use physiological conditions to synthesize inorganic nanoparticles and avoid the use of drastic conditions like high temperature, pressure and use of caustic chemicals. In this way these organism fulfills the requirement of nanotechnology which concerns with the development of experimental procedures for the reproducible synthesis of nanomaterials of controlled size, shape and crystallinity under facile conditions. Biosynthesis of inorganic materials has received the most attention in last few years. Researchers have shown that metal resistant bacterium, Pseudomonas stutzeri AG 259, can result in the intracellular formation of silver and silver sulphide nanoparticles when higher conc. of Ag ions were used for their culture. Bacteria not normally exposed to large conc. of metal ions are also used to grow nanoparticles. Further lactobacillus strains present in butter milk, when exposed to silver and gold ions, will result in the large scale synthesis of nanoparticles with in the bacterial cells. Moreover lactic acid bacteria can be used to grow nanoparticles of alloys of gold and silver. Triangular shaped gold nanoparticles can be formed using lemon grass extract. Also biotransformation of gold acid into gold nanoparticles has control on shape and morphology.