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

•Lead is a major environmental contamination.•We developed a sensitive, selective and fast colorimetric aptasensor for Pb+2.•The designed sensor was based on polyethylenimine and gold nanoparticles.•The sensor showed a high selectivity toward Pb+2 with a low limit of detection.•Our designed aptasensor was successfully used to detect Pb+2 in serum and water.

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 702 pM. Moreover, our fabricated sensor was successfully applied for Pb+2 detection in rat serum and tap water.