Bacteria-Mediated Ultrathin Bi2Se3 Nanosheets Fabrication and Their Application in Photothermal Cancer Therapy

Bismuth selenide (Bi2Se3) attracts a lot of attention nowadays due to its unique electronic and thermoelectric properties. In this study, fabrication of Bi2Se3 nanosheets by selenite-reducing bacterium (SeRB) was first reported. Morphology, size, and location of the biogenic Bi2Se3 are bacteria-dependent. It is difficult to separate Bi2Se3 generated by Bacillus cereus CC-1 (Bi2Se3-C) from the biomass because of strong interaction with the cell membrane. However, Bi2Se3 produced by Lysinibacillus sp. ZYM-1 (Bi2Se3-Z), is highly dispersed in extracellular space with high stability. Further characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) on Bi2Se3-Z indicates that the product is a rhombohedral-phase, ultrathin nanosheet-like structure with an average size of similar to 100 nm. Subsequently, the photothermal performance of Bi2Se3-Z with the irradiation of 808 nm near-infrared (NIR) laser was determined. When the Bi2Se3-Z concentration was 26 mg and irradiation power was 2 W, the photothermal conversion efficiency was calculated as 30.7%. At the same condition, 100% of the MCF7 and A549 cancer cells were killed within 10 min of irradiation in vitro. Moreover, using 1% (v/v) PVP as surfactant, a novel nanodumbbell structure of Bi2Se3 was obtained. Overall, this bacteria-driven Bi2Se3 fabrication paves a new way for biocompatible photothermal nanomaterials.