Microcapsules of PEGylated Gold Nanoparticles Prepared by Fluid−Fluid Interfacial Assembly

Abstract

Amphiphilic, PEGylated gold nanoparticles, of approximately 2 nm average core diameter, were synthesized by reduction of hydrogen tetrachloroaurate in the presence of the ligand (1-mercaptoundec-11-yl)tetra(ethylene glycol). These PEGylated gold nanoparticles were found to assemble cleanly at the oil-water interface. This self-assembly process gave a microencapsulated oil phase, water as the continuous phase, and a monolayer of gold nanoparticles at the oil-water interface. The capsules could be cross-linked from the organic phase by reaction of the chain-end hydroxyl groups of the PEG ligands with suitable electrophiles such as terephthaloyl chloride.

Forced Desorption of Nanoparticles from an Oil–Water Interface

“…Gold nanoparticles stabilized by the amphiphilic ligand thioalkylated tetraethylene glycol 33 spontaneously adsorb at water-trichlorobenzene 8 and water-octafluoropentylacrylate 13 (OFPA) interfaces. For this study we used the latter system, with gold (Au) cores of radii € a core = 2.3 nm and € a core = 5 nm, respectively.…”

“…The spontaneous assembly of nanoparticles to form adsorbed monolayers at fluid-fluid interfaces has been exploited for stabilization of emulsions and foams [1][2][3][4][5] , for creating capsules and nanoporous membranes [6][7][8] , and has found application in phase-transfer catalysis 9,10 and enhanced oil recovery 11 .…”

Synthesis of Nano/Microstructures at Fluid Interfaces

“…[83][84][85] Furthermore, poly(methyl methacrylate-co-acrylic acid) latex particles could be used to generate pH-sensitive colloidosomes. [86] In addition to colloidal particles, nanoparticles, and nanorods, such as silica nanoparticles, [87][88][89][90] CdSe nanoparticles, [27,91] CdSe/ZnS nanoparticles, [92] gold nanoparticles, [93,94] Fe 3 O 4 nanoparticles, [95,96] single-walled carbon nanotubes, [97,98] and CdSe nanorods, [44] can also self-assemble at immiscible fluid interfaces to produce stable emulsions. To obtain mechanically stable capsules from the nanoparticle assemblies, the absorbed nanoparticles need to be fixed at the interface.…”

Adsorption of core-shell nanoparticles at liquid–liquid interfaces

“…19,36 However, the unknown stability of the dispersant anchoring groups at the interface combined with limited hydrophobic shell thickness and homogeneity is likely to lead to aggregation at the oil-water interface and precludes the possibility of obtaining particle spacings larger than 1-2 nm. Regarding water soluble NPs, the very limited available examples include 2 nm Au NPs functionalized with short chain alkyl-oligo(ethylene glycol) thiols, 23 8-40 nm charge-stabilized, citrate-capped Au NPs 29 and tobacco mosaic virus. 37 However, in the first case the use of only four ethylene glycol units led to weak stability and very short interparticle separations.…”