Synthesis of gold nanoparticles via the chemical reduction methods

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Gold nanoparticles have generated a great deal of interest thanks to their unique physical and chemical properties, such as high electrical conductivity, tunable size- and shape-dependent optical properties, biocompatibility and convenient functionalization. They are useful in various applied domains, including but not limited to biotechnology, medicine, electronics, and catalysis. Consequently, optimally efficient large-scale production processes of gold nanoparticles are highly desirable, in order to meet their great market potential. This thesis describes two robust and scalable chemical synthesis methods to fabricate citrate-stabilized spherical gold nanoparticles in aqueous solution. Two modifications of the Turkevich process are used: a) the citrate reduction method, and b) the NaBH4 reduction method. The aim is to optimize the production of gold nanoparticles, resulting in integrated processes which are stable, continuous, efficient, and scalable. By studying the synthesis process, optimized parameters are discovered, and it is shown to be possible to produce gold nanoparticles around 10 nm (SD < 2.87 nm) at the liter scale. Two post-treatment processes, dialysis and diafiltration, were carried out and evaluated on the citrate-stabilized gold nanoparticles. Results revealed that post-treatment removal of byproducts from both HAuCl4 & Na3C6H5O7 reactions and HAuCl4, NaBH4 & Na3C6H5O7 reactions improves the quality of gold nanoparticles, in particular by yielding significantly increased morphological uniformity. In sum, the results described here represent a promising contribution to the industrial manufacture of spherical, citrate-stabilized gold nanoparticles.