In this research, the biosynthesis of glutathione-modified gold nanoparticles was investigated and evaluation of modified nano-adsorbent for its application in loading of flutamide (FLUT) was also performed. Gold nanoparticles (AuNPs) were synthesized in the presence of the Dracocephalum Kotschyi Boiss extract. The response surface methodology (RSM) based on central composite design was used to evaluate and optimize the effect of main factors. The significance of the independent variables and their interactions was tested by means of analysis of variance with 95% confidence level. Results showed that the extract volume, volume of nanogold solution, temperature, extraction time and pH of the sample solution were the main parameters affecting flutamide loading capacity. The optimum operating conditions to achieve maximum loading capacity were determined. The synthesis of AuNPs was confirmed using ultraviolet–visible spectroscopy, FT-IR spectroscopy and X-ray diffraction. The scanning electron microscope (SEM) showed that gold nanoparticles were spherical in size in the range of 30–70 nm. The surface of nanoparticles was chemically modified by glutathione to enhance the bio-stability of the gold nanoparticles and proper interaction between nanoparticles and FLUT. The absence of a peak of 2520.70 cm−1 related to S–H bond in the spectrum of glutathione-modified gold nanoparticles was indicative of the formation of a bond between the sulfur atom and the AuNPs. In the FT-IR spectrum of flutamide-loaded glutathione-modified gold nanoparticles, all the specific peaks of flutamide were observed.
