Synthesis, functionalization and assembly of monodisperse gold nanoparticles with potassium sodium tartrate as reducing agent

Monodisperse gold nanoparticles (AuNPs) are an important guarantee of their scientific value and technical reproducibility in applications. The tartrate has a similar molecule structure and physicochemical properties to citrate, bur is much less reducibility and is usually not favorable for the formation of monodisperse AuNPs. We have prepared monodisperse AuNPs with tartrate (potassium sodium tartrate) as reducing and capping agent. Various parameters affecting the monodisperse properties during the preparation of tartrate-capped AuNPs were analyzed, such as reversing the order of reactant addition and ripening of seeds, while adjusting the synthesis parameters such as time, temperature, and pH value. The final results show that the addition of a trace amount of silver (Ag) ion into chloroauric acid, the monodispersed tartrate-capped AuNPs can be obtained with the size range of 9-40 nm. The fabricated gold seeds and grown tartrate-capped AuNPs have narrow size dispersions (or polydispersity, sigma<10 %). The minimum size dispersion of AuNPs with twice growth steps was as low as 5.73 %. So, the weak reducing agent of tartrate is one of good candidates to synthesize the monodispersity of AuNPs. Additionally, tartrate-capped AuNPs have good stability and can be easily modified and form a large two-dimensional (2D) monolayer nanostructure film.