Biosynthesis of silver nanoparticles using E.coli bacteria

Today, the synthesis of silver nanoparticles is very common due to their many applications in various fields. The synthesis of these nanoparticles is done by means of physical, chemical, or biological methods. However, due to its inexpensive and environmentally friendly features, the biological method is more preferable than the other two methods. Previous research has shown that nitrate reductase enzyme released by microorganisms, is a major factor in the synthesis of silver nanoparticles. In the present paper the effects of nitrate reductase enzyme amount and silver nitrate concentration on nanoparticles synthesis were studied. Silver nanoparticles obtained from biosynthesis using E. coli supernatant were synthesized. Finally, to be more accurate, Uv-VIS spectrophotometer and dynamic light scattering DLS were applied. Using Uv-Vis spectrophotometer, wavelengths for silver nanoparticles in concentrations of 0.001M silver nitrate, one with 5 and the other with 20 cc of the bacterial supernatant containing the soluble nitrate reductase enzyme was calculated as 415, and 405 nm, respectively. Also, the climax was seen in 435 nm for 0.01M silver nitrate with 20 cc of the bacterial supernatant. The spectrophotometer determined the silver nanoparticles’ sizes for 0.001M containing 5 and 20 cc bacterial supernatant as 74.47, and 45.73 nm, respectively. The results showed that by increasing the amount of bacterial supernatant containing the soluble nitrate reductase enzyme, the size of produced silver nanoparticles will be smaller. Also, it was found that by increasing the concentration of silver nitrate the size of produced nanoparticles increases.