Construction of a Heterostructure Composite of Fe-Doped CeO₂ With Buckypaper: Integration as an Electrochemical Aptasensing Platform for Ochratoxin A Detection

The incorporation of nanotechnology into electrochemical sensing has transformed the field of biosensors. Developing smart electroactive heterostructure of 10% Fe-doped CeO2 (Fe0.1Ce0.9O2) and laboratory-prepared buckypaper from multiwalled carbon nanotubes (MWCNs) (L-BP) has resulted in considerable advances in electrochemical aptasensing assays. This heterostructure, when combined with aptamers, acts as redox-active switches that enable the detection and quantification of biomolecular recognition events. The unique redox properties of the Fe0.1Ce0.9O2-L-BPs heterostructure, coupled with the conformational changes of the aptamers upon conjugation, were carefully considered when designing surface-based switchable aptasensing platforms. Moreover, the redox properties of the Fe0.1Ce0.9O2-L-BP heterostructure at the surface changed upon incubation with the aptamer and target analyte, which enabled rapid and highly sensitive detection and measurement of biomolecular interactions. Physical and electrochemical evidences indicated that the Fe0.1Ce0.9O2-L-BP heterostructure aptaswitch developed for the aptasensing detection of ochratoxin A (OTA), could detect concentrations as low as 0.08 nM within the dynamic linear range of 0.1–120 nM. Importantly, this assay does not require any nucleotide modification of the heterostructured particles’ surface, demonstrating a novel approach and new route for electrochemical sensing based on aptamer recognition.