A low Cost Microwave Synthesis Method for Preparation of Gold Nanoparticles

The gold nanoparticles (GNPs) in 15-20 nm size range have attracted attention for fabrication of smart sensing devices in biomedical sciences as diagnostic tools. Citrate capped GNPs are negatively charged, which can be exploited for electrostatic interactions with some positively charged biomolecules like antibody. In this study, we are developing a low-cost technique by using a common microwave system with medium power for synthesizing gold nanoparticles with using sodium citrate (Na\(_{3}\)Ct) reduction in chloroauric acid (HAuCl\(_{4}|).3H\(_{2}\)O). It was found that the comparing with normal thermal method, the reaction by the microwave irradiation was much faster. Besides, effects of the sodium citrate concentration and optical properties of gold nanoparticle swere studied. The optical properties of gold nanoparticles suspension were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-VIS absorption spectroscopy (UV-Vis). Maximum absorbance wavelengths \((\lambda _{max})\) for gold nanoparticles are \(\sim 518-524\) nm with the size of 12-25 nm. The size of gold nanoparticles decreases with increasing concentration of sodium citrate. Besides, the morphology of gold nanoparticles has spherical shape with face-centered-cubic (fcc) crystalline structure.