Detection of Lead Ions in Water Based on the Surface Energy Transfer between Gold Nanoparticles and Fluorescent Dyes

In this paper, a sensitive method for the detection of lead ions in aqueous solution based on the surface energy transfer between gold nanoparticles and fluorescent dyes was established. The fluorescein-modified thrombin aptamer (5′-FAM-GGTTGGTGTGGTTGG-3′) could be selectively transformed to G-quadruplex structure in the presence of lead ions. The conformational change of the aptamer could alter the distance between the energy donor of fluorescent dyes and the energy receptor of gold nanoparticles, resulting in an enhanced fluorescence intensity. The fluorescence recovery efficiency (F/F0) was proportional to the concentration of lead ions in the range of 12.5−100 nM. The linear regression equation was y = 0.910 + 0.007c (R2 = 0.997) with the limit of detection (3σ) of 10 nM. The proposed method was applied to the determination of lead ions in tap water with satisfactory results.

Graphical abstractThe thrombin-binding aptamer wasselectively transferred from random coil to G-quadruplex structure induced by lead ions, which alter the distances and energy transfer efficiencies between FAM-TBA and gold nanoparticles.Figure optionsDownload full-size imageDownload as PowerPoint slide