Surface‐enhanced Raman scattering from analytes adsorbed on gold nanoparticles inside polymer beads

Porous polymer beads with a large inner area were used as a stabilizing matrix for SERS‐active gold particles. A commercially available ion exchanger (SOURCE TM ) was used together with HAuCl 4 . Absorbance measurements and an x‐ray diffraction study confirmed that nanocrystalline gold was obtained in the polymer beads. Transmission electron microscope measurements were performed and showed that larger nanoparticles, 20–100 nm, were obtained on the surface, whereas in the interior smaller particles, approximately 2–10 nm, could be found. Three analytes, mercaptoethanesulfonate, mercaptopropionic acid and thiocyanate, were adsorbed on the gold particles inside the polymer beads. From all analytes enhanced Raman spectra could be obtained. The distribution of analytes adsorbed on gold nanoparticles was investigated by confocal Raman spectroscopy. SERS spectra from the analytes could be observed throughout the polymer bead, indicating a fairly uniform distribution of analytes adsorbed on gold nanoparticles.