A novel disposable dual-sensing platform based on DNA-aptamer amplified with gold nanoparticles/Nb4C3-MXene for simultaneous detection of lead and cadmium
Hassan Karimi‐Maleh, Zhouxiang Zhang, Najmeh Zare, Onur Karaman, Yangpin Wen, Tom Wu, Nianbing Zhong, Li Fu
Abstract
Herein, we designed a special screen-printing carbon electrode system with two independent zones to realize the immobilization of two kinds of aptamers on electrode surface. Nb 4 C 3 -MXene is a remarkable member from MX 3 MXene with many excellent properties. In this study, Nb 4 C 3 -MXene nanosheets were firstly modified onto the screen-printing carbon electrode surface as the substrate materials to offer big surface area and then gold nanoparticles were loaded onto the surface of Nb 4 C 3 -MXene nanosheets through electrodeposition. Afterward, the aptamer-containing double-stranded DNA was spontaneously assembled onto the modified electrode surface through the Au–S bond. Owing to high affinity of aptamers towards the heavy metal ions (Cd 2+ and Pb 2+ in this case), the aptamers tagged with methylene blue and ferrocene would specifically bond with heavy metal ions to form folded structures and competed off from the electrode surface, and then the change of electrochemical signals can be detected by square wave voltammetry. The aptasensor exhibits a good linear response towards Cd 2+ and Pb 2+ from 1 × 10 −10 to 1 × 10 −7 M, and their detection limits are 59.8 pM of Pb 2+ and Cd 2+ of 146.2 pM; LOQ are 93.7 pM of Pb 2+ and 164.8 pM of Cd 2+ , respectively.