PSEUDOPEROXIDASE ACTIVITY OF SILVER NANOPARTICLES (AgNPs) AND CHANGES IN PEROXIDASE ACTIVITY IN MAIZE PLANTS EXPOSED TO AgNPs

Some types of nanoparticles such as gold and silver show interesting chemical properties. Pseudoperoxidase activity has been found in iron- or gold-based materials, but some silver nanoparticles (AgNPs) also exhibit such properties. Pseudoperoxidase activity of AgNPs prepared by green synthesis using sage leaves was studied. The AgNPs (prepared by green synthesis using sage leaves) size ranged from 20 to 50 nm and zeta potential was found to vary from -10 to 20 mV, with absorption maximum being 430 nm. The peroxidase-like activity was monitored in the presence of 5 mM 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (30%). The nanoparticles showed about 80% activity of 1 mU horseradish peroxidase (HRP). In addition, AgNPs were applied to maize seedlings (5 days in hydroponics system) at concentrations of 1 mg/L, 50 mg/L, and 150 mg/L. Peroxidase activity in leaves after 48 hours was 59.5, 67.5, and 57.2 µg.mL-1 of HRP, respectively. Peroxidase activity of untreated plant leaves was 58.8 µg.mL-1 of HRP. Peroxidase activity in roots after 48 hours was 101.6, 109.0, and 156.7 µg.mL-1 of HRP, respectively. The peroxidase activity level of the control variant in root of treatment was 98.7 µg.mL-1 of HRP. The results indicate that the determination of peroxidase activity could be used to assess the phytotoxicity of nanoparticles in plants.