The most effective method for synthesizing gold nanoparticles is the Turkevich method, also known as the citrate reduction method. This method involves the reduction of gold salts, typically gold III chloride AuCl3 , using sodium citrate as both a reducing agent and a stabilizing agent. The method is simple, cost-effective, and produces monodisperse, spherical gold nanoparticles.The parameters of synthesis, such as temperature, reactant concentration, and solvent choice, play a crucial role in determining the size, shape, and properties of the gold nanoparticles obtained.1. Temperature: The reaction temperature can significantly affect the size and shape of the nanoparticles. Higher temperatures usually result in smaller nanoparticles due to faster reduction rates, while lower temperatures may lead to larger nanoparticles. Additionally, higher temperatures can promote the formation of anisotropic shapes, such as rods or triangles.2. Reactant concentration: The concentration of gold salt and reducing agent can also influence the size and shape of the nanoparticles. Higher concentrations of gold salt can lead to larger nanoparticles, while higher concentrations of reducing agent can result in smaller nanoparticles. The ratio of gold salt to reducing agent is crucial for controlling the size and shape of the nanoparticles.3. Solvent choice: The choice of solvent can affect the solubility of the gold salt and the reducing agent, which in turn influences the reaction kinetics and the size and shape of the nanoparticles. Polar solvents, such as water, are commonly used for the synthesis of gold nanoparticles. However, non-polar solvents can also be used to synthesize nanoparticles with different shapes and properties.4. pH: The pH of the reaction mixture can also impact the size and shape of the nanoparticles. A higher pH can lead to smaller, more uniform nanoparticles, while a lower pH can result in larger, more irregularly shaped nanoparticles.5. Stabilizing agents: The choice of stabilizing agent can affect the stability, size, and shape of the nanoparticles. Common stabilizing agents include citrate, thiol-containing molecules, and polymers. The choice of stabilizing agent can also influence the surface properties of the nanoparticles, which can impact their applications in areas such as drug delivery, catalysis, and sensing.In summary, the most effective method for synthesizing gold nanoparticles is the Turkevich method. The parameters of synthesis, such as temperature, reactant concentration, solvent choice, pH, and stabilizing agents, can significantly affect the size, shape, and properties of the obtained nanoparticles. By carefully controlling these parameters, it is possible to synthesize gold nanoparticles with desired properties for various applications.