Biosensors-based polypyrrole/metal-organic framework core-shell for mycotoxins detection

Ochratoxin A (OTA) is a naturally occurring carcinogenic mycotoxin that poses critical risks to human health due to its presence in our daily consumed foods and beverages. Electrochemical aptasensor-based assays have been developed as an alternative to classical methods such as HPLC. However, they need many steps for their construction and labeling, which leads to constrained signal output and reduced large-scale production. It's clear that a highly sensitive, selective, and rapid autosensing platform with high stability and printing technology for large-scale production is still needed for mycotoxins detection.

Here, we showed that biosensor based on core-shell nanostructure formed with conductive polypyrrole (Ppy) and Zirconium nanosized metal-organic framework (Zr-NMOF) allows an electrochemical detection of an ultra-trace of OTA in foods. The nanostructure was formed by controlled chemical polymerization of Ppy on Zr-NMOF to form a core-shell nanostructure followed by DNA aptamers interaction through electrostatic interaction thanks to the positively charged nanostructure provided by P-doping Ppy. We demonstrated that the aptasensor detects OTA through the modification of the electrical properties of the nanostructure thanks to the synergetic effect of the two nanomaterials. A limit of detection of 0.24 pM (0.1 ng/L), and high dynamic linear range were demonstrated. The biosensor also shows high selectivity when compared to OTB detection and can determine OTA directly in red wine with high recovery compared to the standard method.

This work presents the first design of a biosensor based on Ppy/Zr-NMOF/DNA with improved electrical properties and stable properties that can be used as a bioelectronics interface to follow the detection of mycotoxins at a very low concentration of 0.1 ng/L and allows the detection directly in food without any sample treatment. This is an innovative approach that could be adapted for the detection of numerous contaminants by tailoring the specific aptamers.