Optimization of Processing Time, Temperature, and Stirring Rate to Synthesize the Ag Nanoparticles Using Oregano Extract

The plant-based extract can be used to synthesize silver nanoparticles (Ag NPs) as a reducing agent. In the present study, Oregano leaves’ extracts were extracted using ethanol to synthesize Ag NPs. The effects of different parameters such as the processing time, temperature, and stirring rate on the mean particle size, concentration, and zeta potential of the synthesized Ag NPs solutions were optimized using Response Surface Methodology (RSM). At the optimum condition, which includes processing time (30.48 min), temperature (70 ºC), and stirring rate (370.530 RPM), Ag NPs were obtained with 33 nm of the mean particle size, 76.109 ppm of concentration, and +17.2 mV of zeta-potential. In this condition, Ag NPs displayed high antibacterial activity against Gram-negative and Gram-positive bacteria. In addition, the maximum antioxidant activity of 11.7% was obtained at optimum synthesizing conditions.