Synthesis and Characterization of Gold Nanoparticles

The synthesis of GNP was carried out using the trisodium citrate method, following a previously described protocol [34 (link),57 (link),77 (link)]. To initiate the synthesis, a solution of 26.2 mM trisodium citrate dihydrate (Na₃C₆H₅O₇·₂H₂O; molecular weight: 294.10) was prepared in distilled water. Simultaneously, chloroauric acid (HAuCl₄, 2 mM) was dissolved in 10 mL of boiled distilled water, and 4 mL of the prepared trisodium citrate dihydrate solution was added to it. The reaction mixture, composed of the combined trisodium citrate dihydrate and chloroauric acid solutions, was boiled for 1.5 h. After boiling, the mixture was cooled to room temperature and then subjected to centrifugation. The supernatant obtained from the centrifugation was collected and used as the GNP solution.
The synthesized GNP underwent several characterizations to assess their properties. ultraviolet-visible (UV-Vis) spectroscopy was performed to determine the surface plasmon resonance (SPR) peak. Moreover, the structure and shape of the GNP were examined using transmission electron microscopy (TEM), following a previously reported protocol [78 (link)]. The size of the newly synthesized GNP was determined through the quantification of the polydispersity index (PDI) and zeta potential, using dynamic light scattering (DLS) techniques as outlined in previous studies [57 (link),77 (link)]. Overall, these characterization methods provided valuable insights into the properties and morphology of the synthesized GNP.