Gold nanoparticles synthesized by laser ablation in saline medium: an assessment of colloidal stability

Abstract

Gold nanoparticles (AuNPs) produced via pulsed laser ablation in liquids (PLAL) offer significant advantages due to their high purity and absence of ligands. However, their long-term stability is often compromised by aggregation and colloidal destabilization, which are not yet fully understood. This study investigates the influence of different saline agents (NaCl, NaNO3, Na2SO3) and storage conditions on the stabilization of PLAL-produced AuNPs over three months. The nanoparticles were characterized using UV-Vis spectroscopy, XRD, ZP, DLS, XPS, and HRTEM, while computational studies based on density functional theory (DFT) explored the adsorption mechanisms of counterions on the AuNP surface. The results demonstrated that stabilization is strongly influenced by the type of salt and storage conditions, with NaNO3 increasing oxidation and NaCl and Na2SO3 improving size distribution and reducing aggregation. Light exposure negatively affected stability, whereas dark conditions promoted long-term suspension stability. Experimental findings were supported by DFT simulations, revealing strong counterion adsorption on the nanoparticle surface. These findings provide a critical understanding of the interactions governing nanoparticle stability, also offer practical solutions for extending the shelf life of AuNPs. This work paves the way for the development of more robust, contamination-free gold nanoparticles, promising significant advancements in biomedical, electronic, and catalytic applications.