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 (Cu2Se) nanospheres were prepared under mild conditions by a novel biological‐chemical coupling reduction process. The simple process takes place between EDTA‐Cu and Na2SeO3 in presence of an alkaline solution containing NaBH4 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 Cu2+ ions by NaBH4, play a key role, and Cu+ ions not only can promote the generation of Se2− ions as a catalyst, but also can react with Se2− ions to form Cu2Se. XRD pattern, SEM, and TEM images indicated that Cu2Se nanoparticles were tetragonal crystal structure and the nanospheres diameter were about 100 nm. EDX, UV–vis, and FTIR spectra show that the biosynthesized Cu2Se 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