Green synthesis of biocompatible silver nanoparticles mediated by Osmanthus fragrans extract in aqueous solution

A practical, convenient and green method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 2 nm to 30 nm is reported. Silver nitrate was used as silver precursor, and Osmanthus fragrans extract was acted as capping agent as well as reducing agent. The formation of silver nanoparticles was observed by the change of color from colorless to yellow. The as-prepared silver nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopic (HRTEM), UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD) and Fourier transform infra-red spectroscopic (FT-IR). The formation of silver nanoparticles was confirmed by its characteristic surface plasmon absorption peak at 400-450 nm in UV-vis spectra. The TEM and SEM images showed that the as-synthesized silver fine spherical particles are distributed uniformly with a narrow distribution from 2 nm to 30 nm. The HRTEM and XRD results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles. FT-IR data revealed that the silver nanoparticles are coated with Osmanthus fragrans extract. The effects of the silver nitrate and Osmanthus fragrans extract concentrations on the particle size were investigated. The green synthesis method is simple and may be extended to preparation of other noble metal nanoparticles.