The sensitivity of gold-aptamer-nanoconstructs was assessed by challenging the assay to conserved enteroviral sequence containing thymine (or 5-methyuracil, T) (5'ACT ACT TTG GGT GTC CGT GTT TC 3'). Uracil (U) and 5-methyuracil are nucleotide bases that are found in RNA and DNA, respectively, and form hydrogen bonded base pairs with adenine (A). The A-U hydrogen bond is stronger than the A-T hydrogen bond , such that our reported sensitives are likely to be an underestimate of the ultimate limit of detection. The signal transduction mechanism was investigated using 1) spectroscopy, through observation of the changes in absorbance intensity and shift in absorbance maxima, 2) visually inspecting the colour changes of aggregates and 3) application of lateral flow assay. Spectroscopic analysis of the absorbance response of the gold-aptamer-nanoconstructs to log dilutions of target enteroviral nucleic acid, from 1x10 -4 M to 1x10 -14 M, showed that there is a decrease in absorbance amplitude and a blue shift in the absorbance wavelength maxima (Figure ). The response of the gold-aptamer nanoparticle hybrids is sigmoidal, due to finite number of aptamer-based sensing elements that lead to initiation of a signal transduction cascade, in the presence of conserved target enteroviral nucleic acid sequences. Absorption maxima intensity of gold-aptamer-nanoconstructs at 524 nm were significantly reduced in the presence of target enteroviral nucleic acid ≥ 1x10 -7 M (≥ 6.02x10 -13 copies/mL, ≥ 13 log10 copies/mL, ≥ 1.4×10 -14 g/mL, p<0.01, Figure ). These findings were mirrored for the wavelength shift of gold-aptamer-nanoconstructs to changes in target enteroviral nucleic acid (Figure ), such that shifts in peak absorbance wavelength were also observed to 1x10 -7 M (Figure ). Spectroscopic shifts in wavelength of gold-aptamer-nanoconstructs to conserved target enteroviral nucleic acid were also visually observed for conserved target enteroviral nucleic acid concentrations ≥ 1x10 -7 M, which is above the detection limit of spectroscopy (≥ 1x10 M). This difference can be attributed to both the enhanced sensitivity of spectroscopy as a detection technique and the limitations of the human eye to determine subtle changes in absorbance and the submaximal spectroscopic response in absorbance and wavelength shift at 1x10 -7 M . Therefore, to produce an economical detection technique, that is independent of spectroscopy, but demonstrate comparable sensitivity, lateral flow assays were investigated.