Process Parameter Screening Through Fractional Factorial Design for the Synthesis of Gold Nanoparticles

Nanoparticles (NPs) of noble metals such as gold have garnered significant attention due to their novel optical and catalytic properties, their theranostic properties, as they are biocompatible, and they attract considerable interest in a range of applications including targeted drug delivery. In this study, a fractional factorial design (FFD) is applied to systematically investigate the influence of key synthesis parameters (independent variables) at a low level (−1) and a high level (+1), including the reducing agent type (chitosan or trisodium citrate), concentration of reducing agent (10 to 40 mg), pH (3.5 to 8.5), temperature (60 to 100 °C), agitation time (5 to 15 min), and agitation speed (400 to 1200 rpm), on the dependent parameters—particle size and polydispersity index of gold nanoparticles (GNPs). The goal of this study was to provide a comprehensive understanding of the interplay between these parameters and their interaction effect on the characteristics of gold nanoparticles. A fractional factorial design allowed for efficient screening of the parameter space while minimizing the number of experiments required. The results demonstrated that pH, reducing agent, reducing agent–concentration, reducing agent–concentration of reducing agent–pH, and reducing agent–temperature interactions played significant roles in determining the particle size of the synthesized GNPs. Moreover, pH and reducing agent–concentration were identified as the major factors influencing the dispersity of the NPs. This study sheds light on the complex relationships between synthesis parameters and NP characteristics, offering an insight into the capacity for optimizing the synthesis process in order to tailor the desired properties of GNPs. The findings contribute to the growing field of NP synthesis and advance the understanding of the underlying mechanisms governing the formation of GNPs with specific size and dispersity characteristics.