Green synthesis and characterization of silver nanoparticles using Thevetia peruviana: Optimization of temperature and reaction time

Abstract

The present study explores the green synthesis of silver nanoparticles (Ag⁺ NPs) using aqueous extract of stem of Thevetia peruviana, yellow Oleander, a plant rich in bioactive phytochemicals. Nanobiotechnology, a convergence of nanotechnology and biological sciences, enables an eco-friendly and cost-effective synthesis of nanoparticles with tailored physicochemical properties. In this investigation, various synthesis parameters, including temperature (30 °C, 50 °C, and 80 °C) and reaction time (20 to 60 minutes), were optimized to obtain a significant yield of Ag⁺ NPs showing good stability. The biosynthesis of the Ag+ NPs was confirmed by a visible color change from pale yellow to brown and further validated through UV-Visible spectroscopy, which exhibited a characteristic surface plasmon resonance (SPR) peak in 400-450 nm range. Scanning Electron Microscopy (SEM) revealed the morphological characteristics of the synthesized nanoparticles where size of the particles ranged from 0.5-1 micrometre. Optimal synthesis was obtained at 50°C temperature where reaction mixture was processed for 30 minutes, which facilitated efficient reduction and stabilization of Ag⁺ ions. The presence of phytochemicals such as flavonoids, terpenoids, and alkaloids in the stem extract likely contributed to the dual role of reducing and capping agents. This study underscores the potential of T. peruviana as a sustainable bioreductant in the synthesis of silver nanoparticles, offering promising applications in biomedicine, catalysis, and material science under optimized synthesis conditions.