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Updated: Apr 12, 2026
A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay
Published on: February 28, 2015
An aptasensor for selective, sensitive and fast detection of lead(II) based on polyethyleneimine and gold
Seyed Mohammad Taghdisi1, Noor Mohammad Danesh2, Parirokh Lavaee3
1Targeted Drug Delivery Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
Abstract:
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.
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