Context: In the present investigation, acute and subacute toxicity of the biogenic Se nanoparticles (Se NPs) has been reported. Objective: To characterize the Se NPs produced by a bacterium species and to evaluate their toxicity and impact on clinical chemistry and hematological parameters of NMRI mice. Materials and methods: The Se NPs were prepared by Bacillus sp. MSh-1 in a culture medium containing SeO₂ (1.26 mM) and their physiochemical properties investigated using TEM, XRD and FT-IR. The LD₅₀ of Se NPs and SeO₂ were determined and the subacute toxicity evaluated by orally administration of 0, 2.5, 5, 10 and 20 mg kg⁻¹ of Se NPs to male mice for 14 consecutive days. Parameters of blood cells, AST, ALT, ALP, creatinine, BUN, cholesterol, bilirubin, triglyceride and CPK were experimentally measured. Results: The XRD and TEM analyses showed that the spherical NPs were amorphous, in the size range of 80–220 nm. The toxicological evaluation showed that the LD₅₀ values of SeO₂ and Se NPs were 7.3 and 198.1 mg kg⁻¹, respectively. No biochemical changes were observed from the administration of 2.5, 5 and 10 mg kg⁻¹ of Se NPs, but a dose of 20 mg kg⁻¹ was accompanied with signs of toxicity including lower body weight and changes in clinical chemistry and hematological parameters. Conclusion: The biogenic Se NPs were less toxic than synthetic Se NPs and much less (26-fold) toxic than the SeO₂, which demonstrates the important role of Bacillus sp. MSh-1 in conversion of a highly toxic Se compound to the less toxic Se NPs.

Background: Fungal infections affect various parts of the body and can be difficult to treat. Aspergillus infection causes a spectrum of diverse diseases particularly in lung according to host immunity. The two major entities are invasive pulmonary aspergillosis and chronic pulmonary aspergillosis. Candida infections can be superficial or invasive. Superficial infections often affect the skin or mucous membranes. However, invasive fungal infections are often life-threatening. Advances in nanotechnology have opened new horizons in nanomedicine, allowing the synthesis of nanoparticles that can be assembled into complex architectures. Novel studies and technologies are devoted to understanding the mechanisms of disease for the design of new drugs. Objectives: In the present study, the antifungal activity of biogenic selenium nanoparticles (Se NPs) against Aspergillus fumigatus and Candida albicans was investigated. Materials and Methods: Se-reducing bacteria previously identified as Bacillus sp. MSh-1 were used for the intracellular biosynthesis of elemental Se NPs. The shape, size, and purity of the extracted NPs were determined with various instrumental techniques. The nanoparticles antifungal characterization mainly derives from the following pathways: (i) to generate sustained flux of nano-ions from the compounds that deposited on special substrates or imbedded in colloidal or semisolid matrices. (ii) To transport active those ions to sensitive targets on plasma membrane of fungi. Results: The results of energy-dispersive X-ray demonstrated that the purified NPs consisted of only Se. In addition, transmission electron micrographs showed that 120- to 140-nm spherical Se NPs were the most common. An antifungal assay was performed with a standard Clinical and Laboratory Standards Institute broth microdilution method. Minimum inhibitory concentration (MIC) measurements of the antifungal activity of the Se NPs against C. albicans (70 μg/mL) and A. fumigatus (100 μg/mL) showed that yeast cells were more sensitive than mold cells. Conclusions: The MICs against A. fumigatus (100 μg/mL) and C. albicans (70 μg/mL) showed that biogenic Se NPs are useful antifungal agents. Keywords: Selenium Nanoparticles; Antifungal Activity; Metal Nanoparticle; Antifungal Agent; Fumigatus; Aspergillus fumigates; Candida albicans