Controllable synthesis and SERS characteristics of hollow sea-urchin gold nanoparticles

Abstract

Hollow sea-urchin gold nanoparticles (HSU-GNPs) were successfully prepared through a novel one-step galvanic replacement strategy, and their corresponding optical properties was studied in detail. During the synthesis process, the sizes of the interior hollows of the HSU-GNPs could be changed by adjusting the amount of silver nitrate added into hydrogen tetrachloroaurate trihydrate solution. The absorption spectra of the HSU-GNPs showed that the localized surface plasmon resonance (LSPR) peaks were red-shifted with increasing size of the interior hollows in the HSU-GNPs. When the added amount of silver nitrate was up to 6 μl, the LSPR peak of the synthesized HSU-GNP reached 726 nm as a maximum red-shift. Furthermore, the absorption spectra of the HSU-GNPs with different morphologies were theoretically simulated by the finite element method, which was consistent with the experimental results and explained the origin of the red-shift of the LSPR peaks. In addition, the surface-enhanced Raman scattering (SERS) of the sea urchin gold nanoparticles were also investigated using 4-mercaptobenzoic acid as a Raman reporter molecule. Both the experimental and calculated results showed that the HSU-GNPs had stronger SERS enhancement than the solid sea-urchin gold nanoparticles. In particular, the HSU-GNPs prepared by adding 6 μl silver nitrate exhibited a maximum SERS enhancement factor, EF = 1.1 × 10(9), due to the LSPR peak at 726 nm which is near to the excitation wavelength, 785 nm. This feature is significant for designing a biosensor with a super-high sensitivity based on the morphology of the HSU-GNPs.

Facile Synthesis of 64Cu‐Doped Au Nanocages for Positron Emission Tomography Imaging

“…Au-based nanostructures with rough surfaces. [28] In summary, all the Cu-dopedA un anocages synthesized in this study showedL SPR peaks in the NIR region while their wall thicknesses were varied in the range of 4.1-6.4 nm. The NIR absorption makes these nanomaterials ideal for biomedical applications, such as photothermal therapy,p hotoacoustic imaging, and controlled release, due to the high transparency of water and soft tissues in this "biological transparency window".…”

“…When the Cu content was increased by raising the molar ratio of Cu to Au, the resulting rough surface caused a redshift for the LSPR peak to 880 nm. A similar trend has been reported in literature for Au‐based nanostructures with rough surfaces . In summary, all the Cu‐doped Au nanocages synthesized in this study showed LSPR peaks in the NIR region while their wall thicknesses were varied in the range of 4.1–6.4 nm.…”

“…Furthermore, more than 10 5 dipoles were used in all simulations to ensure accurate results. The dielectric constants of pure Au and Cu were taken from Johnson and Christy while the dielectric constant of the Au 52 Ag 48 alloy was extracted from Peña‐Rodríguez . The dielectric constant of the Au‐Cu alloy was taken to be pure Au.…”

“…The dielectric constants of pure Au and Cu were taken from Johnson and Christy [35] while the dielectric constant of the Au 52 Ag 48 alloy was extracted from PeÇa-Rodríguez. [28] The dielectric constant of the Au-Cu alloy was taken to be pure Au. The dielectric constant of the medium and void spaces was taken to be e m = n 2 = 1.78.…”

In situ controlled sputtering deposition of gold nanoparticles on MnO2 nanorods as surface-enhanced Raman scattering substrates for molecular detection

“…The chemical compositions of one bare MnO 2 nanorod and the six MnO 2 @Au nanostructures were all analyzed by energy dispersive spectroscopy (EDS) under FESEM as shown in Fig. 27 It is obvious that the maximum electric field appears mostly around the tiny tips to form the so-called hot spots. The peaks of oxygen and manganese from the MnO 2 nanorods were dominant and a peak for potassium was also observed.…”