Green Synthesis of Silver Nanoparticles Using Crocus Sativus (Saffron) in Various Physical Conditions

Synthesis of nanoparticles by biological systems is a reliable and eco-friendly process. Silver nanoparticles are applied to medical and industrial processes because of their specific properties. Because of antioxidant property of saffron plant (Crocus sativus), it is considered as a reducing agent to synthesize metal nanoparticles. The objective of this study was to investigate the ability of different parts of the saffron plant in reducing silver salt to silver nanoparticles (Ag-NPs) in various temperatures, and present or absent of light.

Three aqueous extracts were prepared from different parts of the plant (stigma, stamen, and purple petal). The Ag-NP synthesize was performed at various temperatures in the present and absent of light in final concentration of 1 mM silver nitrate solution. The prepared Ag-NPs were characterized by ultraviolet-visible spectroscopy (UV-Vis).</em> The mean particle size was investigated using dynamic light scattering (DLS).

The UV-Vis spectrum showed absorption peaks at 400-460 nm. Moreover, the size range of the synthesized nanoparticles was about 15-20 nm. The red stigma and purple petal extracts produced Ag-NPs in the present of light at room temperature. In the absent of light, the absorbance was also observed for the petal extract, whereas the UV-Vis absorption was not observed in stigma extract in the absence of light at room temperature. The stamen extract produced nanoparticles at 60 0</sup>C and 80 0</sup>C in the presence and absent of light, respectively.

Various parts of saffron flower (except green part) showed appropriate ability as reducing and capping agent for synthesis of silver nanoparticles. In addition, light and temperature seemed to have critical effects on the efficiency of plant extracts for producing nanoparticles.