Preparation of Gold Nanocomposites with Tunable Charge and Hydrophobicity via the Application of Polymer/Surfactant Complexation

Abstract

During the synthesis of gold nanoparticle (NP) assemblies, the interfacial charge and hydrophobicity of the primary particles play a distinguished role. In the present article, we demonstrate that the association of poly(ethyleneimine) (PEI) capped gold NPs with sodium alkyl sulfates provide a powerful route for the manipulation of these interfacial properties. Dynamic light-scattering, electrophoretic mobility, UV–vis–near-infrared spectroscopy, nanoparticle tracking analysis, and transmission electron microscopy measurements were used to characterize the PEI/surfactant/gold nanoassemblies. The results indicate the formation of gold NPs surrounded by a PEI/surfactant shell with composition-dependent charge and hydrophobicity. The mean size and the aggregation of the nanoassemblies can be fine tuned by the amount of surfactant bound to the primary gold NPs as well as by the application of controlled mixing methods. The specific features of the prepared nanocomposites may be further exploited in next-generation applications.

Reduction of Tetrachloroaurate(III) Ions With Bioligands: Role of the Thiol and Amine Functional Groups on the Structure and Optical Features of Gold Nanohybrid Systems

“…[8,9]) and chemical approaches [3,4,10]. In the latter case, depending on the applied reducing and stabilizing agents (e.g., sodium borohydride [11,12], sodium citrate [13,14,15], surfactants [16,17], various amines [18], peptides [19,20], or biological organisms [21,22,23]), particles of different shapes and sizes can be produced. In the last decade, the sub-nanometer sized gold nanoclusters (Au NCs) have also became increasingly dominant.…”

Effect of Added Surfactant on Poly(Ethylenimine)-Assisted Gold Nanoparticle Formation

“…In our previous work, it was shown that the charge and hydrophobicity of the PEI-capped AuNPs, prepared at 80 °C, can be modified via their rapid mixing with sodium alkyl sulfate surfactants due to their interaction with the remaining protonated amine groups of PEI . This is attributable to those earlier findings, which revealed that the charge, structure, and hydrophobic character of aqueous PEI-SDS complexes were largely dependent on the protonation degree of PEI as well as on the bound amount of SDS. − These studies also indicated that the various properties of this system could be largely affected through the application of adequate solution preparation methods, due to the nonequilibrium nature of oppositely charged polyelectrolyte/surfactant association at low ionic strengths. − ,− …”

“…In that case, dispersions of overcharged gold nanohybrids with much smaller particle size (d H ≈ 25 nm) and pronounced SPR peaks were produced. 32 The reasons behind these deviations are primarily attributable to the temperature dependent mechanism of gold NP nucleation and growth as well as its interference with the surfactant binding and repartitioning processes. As we have shown previously, in the investigated PEI and HAuCl 4 concentration range, the Au-PEI NP synthesis was completed within 2 h at 80 °C.…”

“…As we have shown previously, in the investigated PEI and HAuCl 4 concentration range, the Au-PEI NP synthesis was completed within 2 h at 80 °C. 32 However, the reduction of Au(III) ions through the amine groups of PEI is a much slower process at 25 °C. This is illustrated in Figure 6a, through the variation of the UV−vis spectrum of HAuCl 4 /PEI premix solution in time (c Au(III) = 0.2 mM, c PEI = 1.2 mM) after its preparation together with the time independent spectrum of the aqueous HAuCl 4 solution.…”

“…33−35,39−42 In the present paper, we provide an economic and simple synthesis method of Au-PEI/SDS nanoassemblies with more versatile structure and size distribution than in the case of the high temperature method. 32 For this aim, we will manipulate various processes, which occur simultaneously at room temperature and primarily governed by the available amine groups of PEI; i.e. the anionic surfactant binding, formation of gold complexes, the reduction of Au(III) ions, and the stabilization of the gold NPs.…”