Controlling the morphology of multi-branched gold nanoparticles

Abstract

We demonstrate a simple and versatile way to achieve high yield synthesis of shape- and size-controlled multi-branched gold nanoparticles (MBNPs). Control over the shape of the MBNPs was achieved by varying the ratio of gold to the mild reducing agent ascorbic acid, using a seed-mediated growth approach. Higher ascorbate concentrations resulted in the smoothing of branches, leading to the yield of relatively more isotropic particles. Furthermore, we found that using much higher silver concentrations in the growth solution resulted in the formation of rod-shaped micro-features together with MBNPs; we postulate them to be cetyltrimethyl ammonium silver bromide crystals. The as-prepared MBNPs show interesting tunable optical properties that are strongly influenced by the particle shape. The results are discussed in terms of plasmon coupling between the core and branches of the MBNPs.

One-step Synthesis of Cetyltrimethylammonium Bromide Stabilized Spherical Gold Nanoparticles

“…Furthermore, the synthesis of CTAB coated Au NPs can be carried out near room temperature which makes them economically viable for large scale production. However, for the synthesis of CTAB capped NPs in the size range of tens of nanometer, usually a seed-mediated, two-step method is followed [16][17][18][19][20][21][22]. First, seed particles are synthesized by reducing Au ions with a strong reducing agent, which are then added to a growth solution.…”

“…The growth solution contains Au precursor, growth directional agents AgNO 3 and CTAB, and a weak reducing agent, ascorbic acid (AA). It is widely believed that AA can only reduce Au(III) to Au(I) in a low pH reaction medium [21,22]. Therefore, for complete reduction of Au ions, seed particles must be added to the growth solution [16,17].…”

To see or not to see: Imaging surfactant coated nano-particles using HIM and SEM

“…Today, nano-particles can be synthesized with a variety of shapes [1][2][3][4][5] and arrangements [6,7], allowing for different applications. To unveil the full potential of these nano-particle based applications [8,9] in general, it is imperative to understand and characterize the wide range of intriguing properties of these nanoscale entities.…”

“…This method is very successful in this research field as it is minimal invasive and can achieve the required resolution of a few nano-meters down into the sub-nanometer * Correspondence to: e.s.kooij@utwente.nl 1 These authors contributed equally to the manuscript range [11]. With the advent of new detectors that allow energy filtering and separation of the different contributions to the signal as well as the possibility to use ultra-low acceleration voltages, the surface sensitivity of the method has also increased substantially.…”

Facile synthesis of hollow urchin-like gold nanoparticles and their catalytic activity

“…In addition, the urchin-like structure leads to large SPR shift from 500 to 800 nm and tunable SPR enhancement light scattering and absorption, making them novel and highly effective contrast agents for in vivo cancer diagnosis and therapy [10]. Many strategies emerge for the construction of size and branchcontrolled urchin-like gold particles [11], mainly through seeding growth approach [12][13][14], where the preferential deposition of atoms on certain facets is dominant [12]. Besides, various molecules are adapted as stabilizer or capping agent to guide the formation of urchin-like structures, such as thiol-terminated molecules [15], cetyltrimethylammonium bromide [8], and sodium dodecyl sulfate [16].…”