Electrochemical aptasensing of cadmium (II) on a carbon black-gold nano-platform

A study on the electrochemical aptasensing of Cd(II) on a screen printed carbon electrode (SPCE) modified with carbon black (CB) and gold nanoparticles (AuNPs) is reported. The nano-platform was prepared by drop casting CB and electrodepositing AuNPs by cycling potential from -400 mV to 1100 mV at 50 mVs(-1) scan rate. The immobilized 36-base thiolated ssDNA aptamer on the SPCE-CB-AuNPs, upon interaction with Cd(II), underwent a conformational change that resulted in change in electrochemical current response. After the optimization of incubation time and aptamer concentration at 30 min and 2 mu M, respectively, the aptasensor detected Cd(II) in the linear range of 1-50 ppb with a limit of detection of 0.14 ppb using square wave voltarrunetry (SWV). The aptasensor was applied in real water sample analysis and the results were validated with inductively coupled plasma-optimal emission spectroscope (ICP-OES). The aptasensor demonstrated good reproducibility, acceptable stability and excellent selectivity towards Cd(II), endorsing potential application in environmental monitoring of Cd(II). (C) 2019 Elsevier B.V. All rights reserved.