Selenium as an essential trace element for the health of the humans was used to hydrothermally synthesis of selenium nanoparticle (Se NPs) using Aloe vera leaf extract (ALE). Effects of synthesis parameters namely; amount of ALE (1–5 ml) and amount of Na2SeO3 solution (10–30 ml), on the particle size and colour intensity of the solution containing Se NPs were studied using response surface methodology. FT-IR spectroscopy, UV-Vis spectrophotometry, DLS analyzer and TEM were used to determine the specifications of the ALE and synthesized Se NPs. Obtained results indicated that the ALE contained several bioactive compounds, which they had hydroxyl and amide І groups in their structures and these two functional groups had key roles in the reduction of the selenium ions to form Se NPs and stabilizing of them. Furthermore, spherical fabricated Se NPs using obtained optimum synthesis parameters, 4.92 mL of ALE and 13.03 mL of Na2SeO3 solution, had colour intensity, mean particle size, zeta potential and polydispersity index values of 3.0% a.u., 50 nm, -18 mV and 0.344, respectively according to the DLS analysis. The synthesized Se NPs had also high antibacterial and antifungal activities against 4 selected pathogenic bacteria and spoilage fungi strains.

The present study focuses on the biogenic synthesis of selenium nanoparticles (Se NPs) using Pelargonium zonale leaf extract under microwave irradiation. Response surface methodology was used to evaluate the effects of the synthesis parameters, namely amounts of the leaf extract (0.5–2.5 ml) and amounts of the 10 mm sodium selenite solutions (15–65 ml), at constant microwave heating (4 min), on the concentration and particle size of the fabricated Se NPs, optimize the synthesis conditions and verify the generated models and the procedures. The obtained results indicated that Se NPs with preferable attributes of mean particle size (50 nm), zeta potential (−24.6 mV), absorbance [34.6% absorbance units (a.u.)] and broad absorption peak (319 nm) were formed at the optimum synthesis conditions including amounts of 1.48 ml and 15 ml Pelargonium leaf extract and sodium selenite solution, respectively. The antibacterial activities of the synthesized Se NPs against Escherichia coli and Staphylococcus aureus indicated that the created NPs had higher antibacterial activities toward the Gram-positive bacteria. Furthermore, the synthesized Se NPs indicated higher antifungal activities against Colletotrichum coccodes and Penicillium digitatum.