Malihe Samadi Kazemi - Department of Chemistry, Faculty of Science, Bojnourd Branch. Islamic Azad University, Bojnourd, Iran
Zarrin Eshaghi - Department of Chemistry, Faculty of Science, Payme Noor University, Tehran, Iran.
Saeideh Rasaeinezhad - Department of Chemistry, Faculty of Science, Payme Noor University, Tehran, Iran.

The development of green processes for the synthesis of nanoparticles is evolving in to an important branch of nanotechnology [1] gold nanoparticles (Au-NPs) hare many applications in biology such as biosensors and DNA labeling [2]. In this study, Au-NPs were synthesized by extract of Dracocephalum kotschyi Boiss. The synthesized gold nanoparticles were characterized by UV- visible spectroscopy, X –ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). The selection of optimum conditions for synthesis of Au-NPs was applied a central composite design (CCD) using Minitab 17software. An analysis of variance (ANOVA) with 95% confidence level was then carried out for each response in order to test the model significance and suitability. The variables were volume of extract, concentration of HAuCl4, pH, temperature and time of extraction. The appearance of a absorption peak at 530 nm of UV- visible spectroscopy and peaks of absorption at 3432, 1631, 1599 and 1384 cm-1 for FT-IR spectroscopy and also, the peaks at 2θ = 38.48, 44.69, 64.05 and 77.50 degree in XRD confirmed the synthesis of nanoparticles of gold. The average of Au-NPs obtained 37.87 nm (Fig. 1). Also, the optimum conditions synthesis of Au-NPs for the studied variables was 1mL, 0.001 mM, pH 8, 60 min and 90C.