Abstract
Abstract Recently, forming a monolayer of nanomaterials is desired for a variety of application. We characterize the nanostructure of Langmuir monolayer of gold nanoparticles (AuNPs) mixed with amphiphilic molecules such as surfactants and lipids by X-ray scattering methods and transmission electron microscopy (TEM). The AuNPs are protected from fusing by hexadecanethiol (Au-16cthiol) or octanethiol (Au-8chtiol). The present results indicate that the interparticle spacing of Au-16chtiol and Au-8cthiol increase while additional anionic surfactant sodium dodecyl sulfate (SDS) was added, but does not alter as increasing surface pressure. The interparticle spacing also increases in Au-8cthiol system by adding lipids. The experimental results indicate that nanoparticles were ordered-packing like “parallelogram” in Au-16cthiol system, but packing randomly in Au-8cthiol system. Besides, the results show that zwitterionic 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine (DPPC) molecules compete for surface site with SDS while anionic 1,2-dihexadecanoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG) molecules compete with SDS not easily due to the electrical repulsion. Furthermore, we also reveal that the AuNPs can form a nanocrystal of (0 0 1) oriented FCC lattice at the air-water interface by mixing with the additional octanethiol. Besides, the thiolated gold nanoparticle monolayer is supported by the lipid monolayer. X-ray reflectivity could reveal the detail structure of such complex monolayers.