Ligand exchange based water-soluble, surface-enhanced Raman scattering-tagged gold nanorod probes with improved stability

We report the preparation of water-soluble, surface-enhanced Raman scattering (SERS)-tagged Au nanorod (NR) probes. That was accomplished by direct ligand exchange of the initial stabilizer with a synthesized Raman-active poly(ethylene glycol) (PEG). The SERS-tagged Au NR probes were characterized by transmission electron microscopy, SERS, and UV–Vis spectroscopy. The Au NR probes exhibited optimized SERS signals due to the coupling of the longitudinal surface plasmon resonance of the Au NRs with the excitation wavelength. Furthermore, they were stable in adverse conditions because the outer PEG protecting layer provided steric stability to them. These multifunctional nanoprobes are expected to have wide applications in biological analysis and biomedicine.