A label-free electrochemical biosensor for highly sensitive detection of gliotoxin based on DNA nanostructure/MXene nanocomplexes.

The use of new functional two-dimensional nanomaterials for construction of advanced biosensors has attracted great attention. Herein, we report an electrochemical DNA (E-DNA) biosensor to detect gliotoxin based on DNA nanostructure-modified MXene (Ti3C2) nanosheets. Tetrahedral DNA nanostructures (TDNs) were facilely immobilized onto the surface of MXene nanosheets through coordination interactions between the phosphate groups on DNA and titanium, which avoids cumbersome and expensive modification of DNA probes. MXene nanosheets possess large surface area to modify a large number of DNA probes and excellent conductivity to facilitate the electron transfer between electrochemical species and the underlying electrode surface. Meanwhile, the unique configuration of TDN enables efficient and rapid binding of target molecules onto electrode surface, thereby producing amplified electrochemical signals. Through combining the merits of the two nanomaterials, the proposed sensor exhibits a wide detection range from 5 pM to 10 nM with a low limit of detection (LOD) of 5 pM. We believe that this work opens a new avenue for development of MXene-based E-DNA biosensors and could be further extended to detect other mycotoxins.