Two-Photon Sensing Of Dopamine By Using Au Nanoparticles
In this paper, we demonstrated a gold nanoparticle based two-photon photoluminescence (TPPL) assay for the detection of dopamine with the detection limit of 0.3 μM. Protonated dopamine molecules can bind bidentately to surface of gold atoms through the catechol group. The adsorption of dopamine displaces the stabilizing agent of citrate groups, and neutralizes the charge of solution, resulting in non-cross linking aggregation of Au NPs. Aggregation of Au NPs could induce significantly enhanced TPPL. Thus, a simple TPPL assay was designed. We have shown that when Au NPs solution was mixed with dopamine, TPPL intensity increased by about 47 times. The mechanism of sensing assay has been discussed. In addition, the TPPL assay was highly selective to dopamine and it can distinguish from uric acid, ascorbic acid and metal ions.