Surface-Enhanced Raman Scattering Investigation of Hollow Gold Nanospheres

Hollow gold nanospheres (HGNs) provide a tunable surface plasmon resonance from 550 to 820 nm by controlling their inner diameter and wall thickness. Although they have been used for biological imaging based on their optical properties in the near-infrared region, their surface-enhanced Raman scattering (SERS) performance has not been thoroughly studied. Herein, HGNs with different surface plasmon resonances were synthesized and functionalized with different Raman reporters. HGNs coupled with Raman reporters, on and off resonant with the laser excitation wavelength, were systematically interrogated in isolated and partially aggregated situations. HGNs with thicker shells generated higher SEAS responses than thinner shells no matter whether they were isolated, or partially aggregated, or whether their surface plasmon resonances were resonant with the excitation wavelength or not. This study gives insight into the basis of the SERS properties for these kinds of materials.