The Quenching Effect of Dopamine Fluorescence in the Presence of Gold Nanorods

Steady-state fluorescence can be used as spectroscopic method for the determination of the binding parameters between a fluorophore and a ligand. If a ground-state complex is formed, the quenching of the fluorescence signal of the fluorophore in the presence of increasing concentrations of a ligand provides information about the binding parameters. But there are many factors involved in the quenching effect of a fluorescence signal. In the present study, I investigated the inner-filter effect on the fluorescence quenching of dopamine molecules in the presence of gold nanorods. The conclusion was that the inner-filter effects were responsible for the quenching of dopamine fluorescence, and not the formation of a ground-state complex between dopamine and gold nanorods. UV-Visible absorption studies did not provide any proof that dopamine has bound onto the surface of gold nanorods.