Selection of a DNA aptamer for the development of an electrochemical aptasensor for the detection of Pb2+

Abstract

In order to develop a simple, highly sensitive and cost-effective electrochemical sensor with high specificity for lead ions (Pb²⁺), the improved magnetic bead-systematic evolution of ligands by exponential enrichment (Capture-SELEX) method was employed to isolate Pb²⁺-specific aptamers. After nine rounds of screening, the aptamer (APTP-3) with a high binding affinity and an excellent specificity for Pb²⁺ was obtained, exhibiting a dissociation constant (K_d) of 535 ± 59 nM. Subsequently, an electrochemical aptasensor for Pb²⁺ detection was designed, utilizing a poly-L-lysine/black phosphorus (PLL/BP) nanocomposite film and AuNPs in conjunction with the APTP-3. The aptasensor demonstrated a significant linear relationship between the change in the DPV peak current and the logarithm of Pb²⁺ concentration, ranging from 0.01 nM to 1 µM, with a detection limit as low as 8.3 pM and good selectivity in the presence of various interfering metal ions. Furthermore, the electrochemical aptasensor exhibited satisfactory performance for Pb²⁺ detection in tap water.