A simple fluorescence and electrochemical
dual-channel biosensor
based on bifunctional Zr(IV)-based metal–organic framework
(Zr-MOF) was proposed to detect Ochratoxin A (OTA). The bifunctional
Zr-MOF, with photoluminescence properties and enormous electroactive
ligands, was exploited to load OTA-specific aptamers for designing
signal probes, greatly simplifying the probe-fabrication process and
improving sensing reliability. Upon specific recognition of aptamer
toward OTA, the anchored probe was released from the sensing interface
into the reaction solution. In this circumstance, the increased amount
of the signal probe in reaction solution led to an enhanced fluorescence
response, while the decreased amount of the signal probe on the sensing
interface resulted in a diminished electrochemical response. According
to the dual-channel signal change with increasing OTA concentration,
the visual fluorescence strategy was established for intuitive OTA
detection, and meanwhile, sensitive electrochemical assay with a detection
limit of 0.024 pg/mL was also achieved with the help of one-step electrodeposition
as a sensing platform. Moreover, the proposed dual-channel assay has
been successfully applied to determine OTA levels in corn samples
with rapid response, superior accuracy, and high anti-interference
capability, providing a promising method for food safety monitoring.