Extracellular synthesis of cuprous selenide nanospheres by a biological‐chemical coupling reduction process in an anaerobic microbial system

Biosynthesis of metal nanoparticles represents a clean, eco‐friendly and sustainable “green chemistry” engineering. Lately, a number of metal selenides were successfully synthesized by biological methods. Here, cuprous selenide (Cu 2 Se) nanospheres were prepared under mild conditions by a novel biological‐chemical coupling reduction process. The simple process takes place between EDTA‐Cu and Na 2 SeO 3 in presence of an alkaline solution containing NaBH 4 and a selenite‐reducing bacteria , Pantoea agglomerans . It is noteworthy that the isolated Pantoea agglomerans and Cu + ions, where the latter are obtained from reducing Cu 2+ ions by NaBH 4 , play a key role, and Cu + ions not only can promote the generation of Se 2− ions as a catalyst, but also can react with Se 2− ions to form Cu 2 Se. XRD pattern, SEM, and TEM images indicated that Cu 2 Se nanoparticles were tetragonal crystal structure and the nanospheres diameter were about 100 nm. EDX, UV–vis, and FTIR spectra show that the biosynthesized Cu 2 Se nanospheres are wrapped by protein and have a better stability. This work first proposes a new biosynthesis mechanism, and has important reference value for biological preparation of metal selenide nanomaterials. © 2016 American Institute of Chemical Engineers Biotechnol. Prog ., 32:1264–1270, 2016