Abstract
Cadmium sulfide nanoparticles were synthesized intracellularly in gene modified Escherichia coli ABLE C. The nanoparticles, a known semiconducting material, which have unique optical and electronic properties, have potential for application in the emerging field of nanoelectronics. To produce nanomaterial cheaply and efficiently, biological methods of synthesis are being explored. Schizosaccharomyces pombe were found having the capacity to synthesize CdS nanoparticles intracellularly in 1983. Recently, in 2004, Sweeney found that E. coli also have ability to synthesize CdS nanoparticles. Morever, in his study, he pointed out that the cellular glutathione can enhance the formation of nanoparticles. Inspried by Sweeney, we constructed a gene modified E. coli ABLE C which could use for glutathione overproduction and attempt to figure out how this parameter can enhance the synthesis of nanoparticles within bacterial cells. Our results showed that nanoparticles biosynthesis increased about 1.6 –fold in gene modified cells compared to wild type cells. HRTEM data showed that the nanoparticles had a Wurtzite hexagonal lattice structure and most of the nanoparticles were in the size range of 2-5 nm. We also observed that nanoparticles synthesized in gene modified cells were dispersed better in water than these in wild type cells. The well dispersion behavior was due to more glutathione coated on the nanoparticles. To our best knowledge, this is the first report using genetic modification to enhance biosynthsis of CdS nanoparticles and to unravel the siginificance of glutathione in this procedure. By understanding parameters of nanoparticles synthesis, it might be possible to modulate the properties of biosynthesized nanopartilces, such as size, shae, and crystal structure.