Functionalized Surface Enhanced Raman Scattering Gold Nanoparticles: Size Correlation of Optical and Spectroscopic Properties and Stabilities in Solutions

Qi Jing Sun, Gilbert C. Walker

Abstract


Gold nanoparticles can be used as surface enhanced Raman scattering (SERS) substrates to amplify the Raman scattering intensities of molecules adsorbed to their surfaces via localized surface plasmon resonance (LSPR). The utility of SERS probes in application depends on the design, therefore it is crucial to understand the impact of nanoparticle diameter on SERS scattering intensity, ease of functionalization, and longevity. Although the optical and spectroscopic properties of gold nanoparticles have been extensively investigated for chemical, bioanalytical, and biomedical applications, the study of the size correlation with such properties for nanoparticles in solutions had rather been limited. This study reports the functionalization of gold nanoparticles of various sizes, ranging from 30 to 90 nm, for use as SERS probes. With the intention of studying monomeric particles, we show that the surface plasmon resonance band and SERS intensities red-shifted and increased with particle size, respectively. Further evaluation revealed that the functionalized particles remained stably dispersed, with no detectable change in SERS signal intensities for up to seven days of storage in biologically-relevant solutions. These findings serve as a promising basis for the further development and exploitation of diagnostically relevant and therapeutically important SERS probes.

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