A Review on Gold Nanoparticles Aggregation and Its Applications

Abstract

In recent years, nanoparticles have been classified in three categories namely nanocrystals, films, and quantum dots. Due to the various properties of composites in comparison to individual particles, the studies that are related to the understanding and characterization of these materials have gained much importance. Solvated metal atom dispersion (SMAD) is a technique which includes the vaporization of the metal in a high vacuum reactor and the co-deposition of metallic vapor on the freeze reactor walls at liquid nitrogen temperature. An organic solvent is used to stabilize the metal atoms in the reaction, to form a solvation sphere, before they reach the frozen reactor walls. After the reaction, nanoparticles are warming at room temperature to form metal colloids. In this stage, depending on the metal concentration, metal type, organic solvent and delay time to stabilize the colloidal nanoparticles, the nanoparticles aggregation produce in different shapes (spherical, clusters, and fractals). The SMAD technique due to reducing and stabilizing the metal nanoparticles in a polymer matrix at the time of synthesis, avoiding metal agglomeration and oxidizing of metal nanoparticles does not produce salt. There is great concentration on these compounds as they can be used in medicine as antibacterial coatings, due to the biocidal action of Au nanoparticles (AuNps). Undeniably, numerous selective homogeneous catalysts from nanoparticles have been reported; however, the only feature is the ability of the polymer chain to protect and stabilize the metal particles from oxidation, therefore, the penetration of the reagents for the desired catalytic reactions is possible.