The aim of this research was to develop stable dye-labelled oligonucleotidenanoparticle conjugates for the detection of DNA related to disease using surface enhanced resonance Raman scattering (SERRS) spectroscopy. In order to achieve this, both gold and silver nanoparticle conjugates were successfully functionalised with thiol- and thioctic acid-modified oligonucleotides. To investigate their viability as biosensors, the stability of the conjugates and their hybridisation efficacy was investigated. It was discovered that the thioctic acidmodified oligonucleotide-nanoparticle conjugates remain stable under these conditions for a substantial period of time compared to thiol-modified oligonucleotide nanoparticle conjugates. The nanoparticle conjugates were functionalised for use in surface enhanced resonance Raman scattering (SERRS) spectroscopy by the incorporation of an isothiocyanate dye molecule. Not only were the conjugates SERRS active, they were also proven to exhibit enhanced stability for both thiol- and thioctic acid-modified oligonucleotide nanoparticle conjugates. The thioctic acid-modified oligonucleotide nanoparticle conjugates were investigated for their use as sensors to detect specific DNA sequences. Both gold and silver nanoparticle conjugates were shown to retain their biological activity by hybridising with complementary DNA sequences. This was monitored colorimetrically, due to the characteristic colour changes associated with aggregation of gold and silver nanoparticles, and by monitoring the hybridisation-induced red-shift of the surface plasmon band by UV-Vis spectroscopy. The hybridisation-induced aggregation methodology was also extended to dye-labelled nanoparticle conjugates that were investigated by SERRS. A method for characterising oligonucleotide-nanoparticle conjugates using a fluorescent DNA intercalator, SYBR green I, was developed. This study showed that SYBR green I can be used as a rapid method for determining the melting profiles of individual nanoparticle conjugates and the hybridisation efficiency of the immobilized oligonucleotides.