Development of an ultrasensitive rGO/AuNPs/ssDNA-based electrochemical aptasensor for detection of Pb2+

The present work is performed on Pb2+ detection via electrochemical sensor. The novel aptasensor was developed by modification of glassy carbon electrode (GCE) with reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) modified with ssDNA. The synthesized nanoparticles were characterized by HRTEM (high resolution transmission electron microscopy), SAED (selected area electron diffraction), UV-Vis spectrophotometer, FTIR, and XPS. The rGO was prepared by electrochemical reduction and thickness of rGO sheet was 0.5 to 1 nm. The average AuNPs size was 20-25 nm. The Pb2+ ion binds with specific ssDNA, and it will induce conformational changes of the aptamer and corresponding modulation of electrochemical signals. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for Pb2+ detection and optimization of sensor. The proposed aptasensor exhibits high sensitivity toward detection of Pb2+ ions with a detection limit of 1.52 nM and linear range of 5-50 nM at a signal-to-noise ratio of 3. Moreover, this aptasensor produces satisfactory results in environmental water samples analysis. The results of the newly developed aptasensor show better sensitivity and selectivity than the previously described electrochemical sensor.