Colorimetric detection of epinephrine using an optimized paper-based aptasensor

A simple label-free colorimetric detection of epinephrine has been demonstrated based on its interaction with aptamer functionalized gold nanoparticles. The role of different parameters such as morphology of AuNPs, aptamer concentration and salt destabilization has been thoroughly investigated to enhance the performance of the sensor in terms of sensitivity and specificity. A range of common interfering agents such as 3,4-dihydroxyphenylacetic acid (DOPAC), tryptophan, dopamine, ascorbic acid etc. showed very little/no aggregation in the solution which indicates the specificity of the sensor. The sensor was then tested on a hydrophobic paper substrate for the development of a cheap, portable and point of care diagnostic tool. A visible change in colour from red to blue was observed in the solution with increasing concentration of epinephrine. The present approach gave a detection limit of 0.9 nM using UV-visible spectroscopy which is by far the lowest detection limit of epinephrine using any colorimetric approach.