Hybridization Mechanism of Nonamphiphilic Capped Gold Nanoparticles in the Presence of a Surfactant

The functionalization of gold nanoparticles is necessary to obtain a stable dispersion in organic solvents. For this purpose, different types of ligands, soluble or insoluble in aqueous solutions, have been developed. The character of the ligand and the presence of nonpolar or polar sides of the molecules determine the ability to create monolayers at the air–water interface. Thus, to investigate optical resonances of nanoparticle assemblies in Langmuir monolayer amphiphilic stabilizing ligands, their presence should be avoided or their concentrations should be accurately controlled. In this work, citrate-stabilized and PEGylated gold spherical nanoparticles are used to examine and describe the mechanism of their hybridization in situ. This strategy enables an understanding of the hybridization phenomenon of gold nanoparticles, which are not perturbed by capping agents capable of creating a monolayer. For the first time, we have shown that the mechanism of hybridization is strongly dependent on the presence and molecular orientation of the model amphiphilic molecules. Moreover, the zigzag character of hybridization can be controlled by tailoring the amount of the surfactant in the monolayer and its physical state.