The design of a peptide linker group to enhance the SERS signal intensity of an atto680 dye-nanoparticle system

The Surface enhanced resonance Raman spectroscopy (SERRS) spectra of three modified atto680 dyes were recorded using Au nanoparticles and an excitation laser operating at 670 nm. The dyes were modified with linker groups based on the small peptides, Cys, Cys-Gly and Cys-Gly-Gly. The Cys thiol group acted as the coupling point to the Au surface and the Gly -NH2 group used to attach the dye. The maximum signal was recorded for the Cys-Gly linker. This gave a signal intensity for the 577 cm(-1) Raman peak of the atto680 dye that was more than 27 times greater than the unmodified dye. The Au nanoparticles used had a diameter of 49.8 +/- 1.2 nm and were synthesised by the citrate reduction method. The Raman dye-AuNP probes were also used in an immunoassay to detect mouse IgG in the femto mole range. Copyright (C) 2010 John Wiley & Sons, Ltd.