An aptasensor for selective, sensitive and fast detection of lead(II) based on polyethyleneimine and gold nanoparticles.

Lead (Pb), as a major environmental contaminant, could be harmful to humans when inhaled or ingested. In this study, we developed a sensitive, selective and fast colorimetric aptasensor for Pb(+2) based on polyethylenimine (PEI) and gold nanoparticles (AuNPs). In the absence of Pb(+2), aptamer binds to PEI. So the well-dispersed AuNPs remain stable with a wine-red color. Upon the addition of Pb(+2), a conformational change happens and a G-quadruplex aptamer/Pb(+2) complex is formed, leading to the aggregation of AuNPs and a color change to blue. This sensor showed a high selectivity toward Pb(+2) with a limit of detection (LOD) as low as 702pM. Moreover, our fabricated sensor was successfully applied for Pb(+2) detection in rat serum and tap water.