Label-free electrochemical biosensor based on GR5 DNAzyme/Ti3C2Tx Mxenes for Pb2+ detection

Abstract

• The interactions of Ti 3 C 2 T x Mxenes toward different DNA molecules were studied. • Pb 2+ could enhance the oxidation peak current of GR5 DNAzyme/Ti 3 C 2 T x Mxenes GCE. • Label-free sensor was fabricated based on GR5 DNAzyme/Ti 3 C 2 T x Mxenes GCE. • This sensor was successfully applied to detect Pb 2+ in rat and chicken samples. The interactions between nucleic acids and nanomaterials have been often utilized to design the electrochemical biosensor due to easy preparation, adsorptive tunability and high sensitivity. In this study, we have prepared a new electrochemical biosensor for Pb 2+ detection based on GR5 DNAzyme/Ti 3 C 2 T x Mxenes modified glassy carbon electrode (GR5 DNAzyme/Ti 3 C 2 T x Mxenes-GCE). GR5 DNAzyme is an RNA-cleavage-type DNAzyme that shows high specificity towards Pb 2+ . With the presence of Pb 2+ , the cleavage of GR5 DNAzyme is activated at a ribo -adenine (rA) site in the substrate stranded DNA, leading to the unwinding of double-helix structure. This can enhance the adsorptive property of Ti 3 C 2 T x Mxenes toward GR5 DNAzyme, which favors the ion intercalation into the Ti 3 C 2 T x Mxenes and induces the increase of oxidation peak current. Therefore, we have successfully applied GR5 DNAzyme/Ti 3 C 2 T x Mxenes-GCE to detect Pb 2+ with a linear range from 0.5 to 32 nM and a detection limit of 0.1 nM. This electrochemical biosensor is simple, sensitive and selective for Pb 2+ determination that it should find some potential applications in food safety inspection and environmental monitoring.