Three accelerated methods based on microwave, hydrothermal and conventional heating in the green synthesis of selenium nanoparticles using garlic aqueous extract: Screening and characterization

Abstract

Selenium nanoparticles (Se NPs) have unique biological characteristics, including anticancer, antioxidant and antimicrobial activities. Furthermore, the green synthesis of Se NPs using plant extracts, due to their natural reductant and stabilizer molecules, can intensify the process with minimal toxic effects on the human body and the environment. Se NPs have been synthesized using an aqueous extract of garlic and three accelerated heating methods based on microwave (800 W for 2.5 min), hydrothermal (temperature and pressure of 121 ºC and 1.5 atm, for 15 min) and conventional (at 150 ºC for 1 h) heating using a heater with stirring. Solution mixtures containing 20 mL of the prepared extract and 5 mL of sodium selenite solution (10 mM) were exposed to these three mentioned heating methods. Fourier transform infrared spectroscopy, UV-Vis spectrophotometry, dynamic light scattering analysis and transmission electron microscopy were used to assess characteristics of the formed Se NPs. The results showed that the fabricated Se NPs via microwave, autoclave and conventional heating methods had minimum particle size (107 nm) and polydispersity index (0.155), and maximum zeta potential (-38.7 mV) values. Furthermore, the spherical formed Se NPs using garlic extract and under microwave, conventional and autoclave heating methods had antioxidant activity of 44.2, 34.8 and 32.6 %, respectively. The formed Se NPs also indicated high antibacterial activity toward Escherichia coli and Staphylococcus aureus bacteria strains.