Selenium has an important role in the health of animals and humans. However, the most common forms of selenium, such as selenate and selenite, can easily be overdosed on in plants and animals. There is a small space between the essential and toxic effects of selenium. Surprisingly, selenium nanoparticles have shown higher biological properties with lower toxic risk than other forms. Therefore, the synthesis or production of selenium nanoparticles is attracting attention, and their application is increasing over the days in nutrition, medicine, and others. In our study, selenium nanoparticles were synthesized by biological and chemical reduction methods, toxicity and antidote efficacy were determined in a simple way, and nanofibers rich in different types of selenium nanoparticles were produced by electrospinning technique.
The results show that organic red selenium nanoparticles around 250 nm were transformed by bacteria, which is amorphous in shape. Organic selenium nanoparticles with sizes from 50 to 500 nm within yogurt as powder also have been produced by the combination of steps for conversion of selenium nanoparticles and yogurt making at the same time. Finally, 2000 mg/kg of selenium-enriched yogurt powder was obtained by lyophilization and grinding. Inorganic red amorphous selenium nanoparticles in liquid form with sizes from 100 nm to 100 µm have been synthesized from the reaction of 500 mg/L sodium selenite and 10 g/L ascorbic acids. Red selenium nanoparticles in powder form were produced by reacting sodium selenite at 10,000 mg/L and ascorbic acids at 100 g/L. Grey selenium nanopowder, which is hexagonal crystalline form, is converted by heat treatment at 85 ˚C for 10 min from red powder. The selenium nanolayer in the inner surface of the medical tube was created by a circulating flow of selenium nanosuspension using a peristaltic pump with a flow rate of 95 rpm at room temperature for 30 min. Also, the selenium nanolayer with crystal structure was converted at a higher temperature of 85 °C. PVC tubes are coated with selenium nanoparticles with a size of 100–200 nm, and these single and small particles attach to form more significant clusters with a size of 2 µm. The silicone surfaces were covered with a considerable amount of selenium nanoparticles with thickness of about 16 µm and are evenly distributed over all surfaces. We found that the biologically synthesized selenium nanoparticles at 800 mg/L have no toxic effect on P. caudatum. The supplementation with selenium nanoparticles reduced the lethal concentrations of toxicants by 2-fold compared to the un-supplemented group. Namely, the lethal concentrations were decreased in the selenium supplemented groups from 1.25 mg/L to 2.50 mg/L for silver nanoparticles, 2.50 mg/L to 5.0 mg/L for silver nitrate, 10.0 mg/L to 20.0 mg/L for sodium selenite, and from 20.0 mg/L to 40.0 mg/L for sodium selenate. Surprisingly, the survival time of Paramecium has significantly extended by supplementation with selenium nanoparticles in the experimental group. Red and grey selenium nanopowder of 1 to 10% enriched nanofibers are typically amorphous with a diameter range of 100 nm to 100 µm and a specific surface area of around 4 to 40 m2 g−1. Significantly, the mean diameter was approximately 500 nm with a specific surface area of 8 m2 g−1 at all concentrations of selenium nanopowder. The length of the nanofibers is 5093 km cm−3 with a diameter of 500 nm, which is derived from a 1 mL polymer solution. Bead formation was observed inside and outside the fiber, which is caused by the concentration of nanopowder. In the presence of in-situ synthesized selenium nanoparticles, we have synthesized selenium nanoparticles in a polymer solution by dissolving 500 mg/L of sodium selenite with 10 g/L of ascorbic acids in 80% ethanol. In that case, we have a pink nanofibrous sheet with a smooth and soft surface containing 1250 mg/L of selenium and smaller than 50 nm. They are also amorphous with 500 nm of average diameter size. The in-situ synthesized selenium nanoparticles are well dispersed in a PVB polymer solution and located inside the fiber.