In situ reduction of gold nanoparticles-decorated MXenes-based electrochemical sensing platform for KRAS gene detection

Abstract

In this work, gold nanoparticles@Ti₃C₂ MXenes nanocomposites with excellent properties were combined with toehold-mediated DNA strand displacement reaction to construct an electrochemical circulating tumor DNA biosensor. The gold nanoparticles were synthesized in situ on the surface of Ti₃C₂ MXenes as a reducing and stabilizing agent. The good electrical conductivity of the gold nanoparticles@Ti₃C₂ MXenes composite and the nucleic acid amplification strategy of enzyme-free toehold-mediated DNA strand displacement reaction can be used to efficiently and specifically detect the non-small cell cancer biomarker circulating tumor DNA KRAS gene. The biosensor has a linear detection range of 10 fM -10 nM and a detection limit of 0.38 fM, and also efficiently distinguishes single base mismatched DNA sequences. The biosensor has been successfully used for the sensitive detection of KRAS gene G12D, which has excellent potential for clinical analysis and provides a new idea for the preparation of novel MXenes-based two-dimensional composites and their application in electrochemical DNA biosensors.

Keywords: CtDNA; MXenes; biomarker; biosensor; electrochemical; gold nanoparticle.

SCHEME 1

Schematic illustrations of (A) the synthesis route for AuNPs@Ti3C2 MXenes nanocomposites, and (B) electrochemical sensing platform for KRAS gene detection via toehold-mediated strand displacement reaction.

FIGURE 1

SEM images of Ti₃AlC₂ (A). TEM images of Ti₃C₂ (B) and AuNPs@Ti₃C₂ MXenes (C). (D) XRD of Ti₃AlC₂ (a), Ti₃C₂ (b), AuNPs@Ti₃C₂ (c). (E) Elemental mapping images of AuNPs@Ti₃C₂.

FIGURE 2

Electrochemical impedance spectroscopy (EIS) response of bare GCE (a), gold nanoparticles @ Ti₃C₂ MXenes/GCE (b), DNA double-strand probes/gold nanoparticles @Ti₃C₂ MXenes/GCE (c), MCH/DNA double-strand probes/gold nanoparticles@ Ti₃C₂ MXenes/GCE (d), probe DNA/target DNA/MCH/DNA double-strand probes/gold nanoparticles@Ti₃C₂ MXenes/GCE (e) in 5 mM [Fe(CN)₆]^3−/4− containing 0.1 M KCl.

FIGURE 3

(A) Square wave voltammetry (SWV) curves of the DNA biosensor to KARS G12D gene at a series of concentrations, from down to top (black arrow): 0, 10⁻⁵, 10⁻⁴,10⁻³, 10⁻², 10⁻¹, 1, 10 nM. (B) The logarithmic plot of the current value of the oxidation peak versus the KARS G12D gene concentrations from 10⁻⁵ nM–10 nM. Error bars represent the standard deviations of three independent experiments.

FIGURE 4

Specificity investigation of five different DNA sequences: Target DNA KARS G12D (T), single-base mismatched DNA (1 M), two-base mismatched DNA (2 M), three-base mismatched DNA (3 M), random DNA sequence (R). Error bars represent the standard deviations of three independent experiments.