RESUMO
We established a sensitive method for the detection of lead ions in aqueous solution based on the surface energy transfer between gold nanoparticles and fluorescent dyes. The fluorescein-modified thrombin aptamer (5′-FAM-GGT TGG TGT GGT TGG-3′) can be selectively transformed to G-quadruplex induced by lead ions. The conformation changes of the aptamer can alter the distance between the energy donor of fluorescent dyes and the energy receptor of gold nanoparticles, and further enhance the fluorescence intensity. The fluorescence recovery efficiency ( F/F0 ) is proportional to the concentration of lead ions in the range of 12. 5-100 nmol/L following the linear regression equation of y=0. 910﹢0. 007c(R2=0. 997)and the limit of determination is about 10 nmol/L. The proposed method has been applied to the determination of lead ions in tap water with satisfied results.