Magnetic reduced graphene oxide/nickel/platinum nanoparticles (rGO/Ni/PtNPs) micromotors for mycotoxin analysis in food samples were developed for food-safety diagnosis. While the utilization of self-propelled micromotors in bioassays has led to a fundamentally new approach, mainly due to the greatly enhanced target-receptor contacts owing to their continuous movement around the sample and the associated mixing effect, herein the magnetic properties of rGO/Ni/PtNPs micromotors for mycotoxin analysis are additionally explored. The micromotor-based strategy for targeted mycotoxin biosensing focused on the accurate control of micromotor-based operations: 1) on-the-move capture of free aptamers by exploiting the adsorption (outer rGO layer) and catalytic (inner PtNPs layer) properties and 2) micromotor stopped flow in just 2 min by exploiting the magnetic properties (intermediate Ni layer). This strategy allowed fumonisin B1 determination with high sensitivity (limit of detection: 0.70 ng mL-1 ) and excellent accuracy (error: 0.05 % in certified reference material and quantitative recoveries of 104±4 % in beer) even in the presence of concurrent ochratoxin A (105-108±8 % in wines). These results confirm the developed approach as an innovative and reliable analytical tool for food-safety monitoring, and confirm the role of micromotors as a new paradigm in analytical chemistry.
Keywords: adsorption; analytical methods; electrochemistry; micromotors; mycotoxins.
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