Morphology modification of gold nanoparticles from nanoshell to C-shape: Improved surface enhanced Raman scattering

Abstract

Morphology modification of nanostructures is of great interest, because it can be used to fabricate nanostructures which are hard to be done using other methods. Different from traditional lithographic technique which is slow and expensive, morphology modification is easy, cheap, and reproducible. In this paper, modification of the optical and morphological properties of a hollow gold nanoshell (HGNS) is achieved by using H2O2 as an oxidizer. The reshaping of these nanostructures has been demonstrated as a consequence of an oxidation process in which HGNSs are dissolved by H2O2 under the acidic conditions provided by HCl. We investigate the oxidation process by a transmission electron microscope and propose a reshaping model involving four different shapes (HGNS, HGNS with hole, gold nanoring, and C-shaped gold nanoparticle) which are corresponding to the oxidation products of HGNSs at different pH values. Besides, the surface enhanced Raman scattering (SERS) activity of each oxidation product has been evaluated by using rhodamine 6G as the Raman active probe. It has been observed that the C-shaped gold nanoparticles which are corresponding to the oxidation products at the minimum pH value have the highest SERS activity and this result can also be interpreted by discrete-dipole approximation simulations. We demonstrate that the morphology modification of HGNSs becomes possible in a controlled manner using wet chemistry and can be used in preparation of gold nanoparticles such as HGNS with hole, gold nanoring, and C-shaped gold nanoparticle with large SERS activity. These nanostructures must have potential use in many plasmonic areas, including sensing, catalysis, and biomedicine.

Specific Detection of Carcinoembryonic Antigen Based on Fluorescence Quenching of Hollow Porous Gold Nanoshells with Roughened Surface

“…Xia’s group uses PVP as the surfactants for the preparation of Ag template and the following reaction of synthesizing hollow gold nanocubes . In our previous report, sodium citrate is used in the preparing of Ag nanoparticles, and CTAB is used in the fabrication of hollow gold nanoparticles . Both CTAB and PVP are commonly used surfactants in preparing hollow gold nanoparticles.…”

“…33 In our previous report, sodium citrate is used in the preparing of Ag nanoparticles, and CTAB is used in the fabrication of hollow gold nanoparticles. 34 Both CTAB and PVP are commonly used surfactants in preparing hollow gold nanoparticles. However, the influence of PVP and CTAB on the fluorescence quenching efficiency remains uninvestigated.…”