Accumulation of silver nanoparticles and its effect on the antioxidant capacity in Allium cepa L

Abstract

Nanotechnology is currently an important worldwide study field because it provides control on matter at a nanometric scale. In food and agricultural fields, the applications of this technology are in early stages. Onion is one of the main vegetables grown in the world. Onion is a low calorie food which contains a large amount of flavonoids. In this work, silver nitrate application in onion was evaluated. An onion crop was developed at the University Antonio Narro in Saltillo, Mexico. Two methods of silver nitrate application were used (a nutritive solution: 0, 20, 40 and 80 mg/L of AgNO₃; and foliar spray: 0, 20 and 40 mg/L of AgNO₃). The samples were taken at 30, 60 and 90 days after transplanting. Total antioxidant capacity, silver accumulation and silver nanoparticles formation were determined. The results showed that silver nitrate had a positive effect on total antioxidant capacity when it was applied as a nutritive solution. Silver accumulation in different tissues depended on the silver nitrate application method. The silver nanoparticles formation was positive; furthermore, these nanoparticles were found at a greater extent on samples where the AgNO₃ foliar spray application method was used. The average of silver nitrate nanoparticles size was from ~300 nm to ~1000 nm.