Biocompatible gold/silver nanostars for surface-enhanced Raman scattering

Raman-enhancing properties of chitosan (CS)-coated gold/silver nanostars (Au/AgNSs) were demonstrated by using them as a surface-enhanced Raman scattering (SERS) probe. Based on the energy-dispersive X-ray spectroscopy element distribution maps and highly enhanced SERS spectra, we suggest that the incorporation of silver into the NS tips leads to a stronger SERS behavior. The SERS spectra of the proteins adsorbed on the NS surface greatly differ from their respective Raman spectra in both the band positions and relative intensities, indicating that the protein molecules penetrate through the CS coating layer and interact closely with the NS surface. Raman and SERS spectra of Chlamydia trachomatis protease/proteasomelike activity factor are reported for the first time, demonstrating the potential of these NSs for the development of a diagnosis method for Chlamydia based on SERS. The results showed a good SERS performance of the Au/AgNSs and their potential for SERS detection of biomolecules.