Biosynthesis and antioxidation of nano-selenium using lemon juice as a reducing agent

Nano-selenium was synthesized using lemon juice as a reducing agent. The experiments showed that pH value affected greatly the shape and the size of the prepared nano-selenium. At pH 9, lemon juice could reduce 50 mmol/L of selenite ions to nano-selenium with particle size between 50 and 90 nm, which was spherical and well dispersed. Lemon juice acted as both a reducing agent and a stabilizer in the synthesis of nano-selenium, in which the chemical interaction between biomolecules and the nano-selenium surface was the basis for the stable existence of nano-selenium. The selenite concentration influenced the formation of nano-selenium, and a low selenite concentration was beneficial to obtain small particles. The achieved nano-selenium exhibited a strong antioxidant activity positively related to concentration. The comparative study showed that the antioxidation of nano-selenium is weaker than that of vitamin C but higher than that of lemon juice. Graphical abstract Green synthesis of nano-selenium from lemon juice, selenium nanoparticles coated with macromolecules, and antioxidant activity.