Unfunctionalised gold nanoparticles, when imaged using TEM, were dispersed appearing as individual nanoparticles or in small clusters (<10 gold nanoparticles), Figure . In comparison, gold-aptamer-nanoconstructs were composed of large nanoparticle complexes (>50 gold nanoparticles), Figure . The distribution of unfunctionalised gold nanoparticles and gold-aptamer-nanoconstructs and the interaction of light with surface plasmon on free and aggregated nanoparticles could be attributed to the observed visual and spectral differences . Dispersed gold nanoparticles absorb and reflect light at ~ 500 nm and ~700 nm producing a deep red colour. Whereas, gold-aptamer-nanoconstructs behave like larger gold-nanoparticles and the surface plasmon resonance absorption wavelength is shifted, such that red light is absorbed, and blue light is reflected, producing a purple colour. These observed visual and spectral differences between disaggregated nanoparticles and goldaptamer-nanoconstructs were used as a signal transduction mechanism to detect conserved target enteroviral nucleic acid sequences.