Gold Nanoparticles Self-Assemble Into Large Arrays

Scientists in China have have devised a method to induce self-assembly of gold nanoparticles into centimeter-scale arrays for use in biosensors and catalysis.

AsianScientist (Nov. 17, 2017) – In a study published in the Advanced Materials Interfaces, scientists in China have developed a method to induce the self-assembly of gold nanospheres into centimeter-sized arrays.

Regular assemblies of gold (Au) nanoparticles into two-dimensional (2D) monolayer films have received increasing attention in recent years because of their potential applications in chemical and biological sensors, photocatalysis and photonic or electronic devices. Traditional self-assembling approaches to fabricate Au nanoparticle array films include the Langmuir–Blodgett (LB) technique and oil-water interfacial self-assembly technique.

However, the LB technique requires special and precise equipment and is usually limited to hydrophobic nanoparticles. On the other hand, the oil-water interfacial self-assembly method is only suitable for hydrophilic nanoparticles, and forms fragile array films that break easily when the oil phase evaporates. The self-assembly of highly ordered 2D Au nanosphere arrays at an ultra-large scale remains a great challenge.

In this study, a group of researchers at the Hefei Institutes of Physical Science succeeded in using a bi-solvent system at the air-water interface to cause spherical Au nanoparticles to self-assemble into ultra-large arrays.

Their method consisted of two steps. Firstly, Au nanoparticles were induced to float on the water surface. The sparse Au nanoparticles were then compressed into a densely-packed array by creating an effective capillary gradient along the water surface.

The researchers reported that the effects of the capillary gradient depends on the water solubility and vapor pressure of the compressing solvent. They were able to organize monodispersed Au nanospheres into dense, periodic 2D Au nanosphere arrays at a centimeter-sized scale.

The assembled Au nanoparticle arrays could provide a promising and important platform for practical applications in biosensors and catalysis because of the unique size-, shape-, and dielectric-dependent optical properties of Au nanoparticles.

The article can be found at: Liu et al. (2017) Capillary Gradient-Induced Self-Assembly of Periodic Au Spherical Nanoparticle Arrays on an Ultralarge Scale via a Bisolvent System at Air/Water Interface.


Source: Chinese Academy of Sciences.
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