Gold nanoparticle based colorimetric probe for dopamine detection based on the interaction between dopamine and melamine

We report on a probe for the colorimetric and bare-eye detection of dopamine (DA). The optical effect is based on the finding that DA inhibits the melamine-induced aggregation of red gold nanoparticles (AuNPs) to form blue AuNP clusters. We presume that the aggregation induced by melamine is due to its strong hydrogen-bonding interactions with DA. The color changes can be monitored by spectrophotometry or the bare eye. The probes works over the 33 nM to 3.33 mM DA concentration range, and levels down to 33 nM can be quantified. The nanoprobe was successfully applied to the determination of DA in spiked serum.