Disclosed are Surface Enhanced Resonance Raman Spectroscopy (SERRS) probes and their use in detection methods for bioassays. Further disclosed is signal optimization of surface enhanced resonance Raman probes achieved by chemical modification of the probes. Also disclosed are methods for increasing the Raman cross-section by varying the chemical composition of a linker group linking a signal molecule to a nanoparticle surface. The signal molecules, such as dyes, may be modified with a linker group designed to both enhance the SERRS signal and to couple the signal molecule to the nanoparticle surface.