posted on 2023-01-09, 10:03authored byXuan Zhou, Zongbao Sun, Xiaoyu Su, Kaiyi Zheng, Xiaobo Zou, Wen Zhang
Ochratoxin A (OTA) frequently contaminates grains and
consequently
threatens human health. Herein, we develop a regenerable signal probe
and apply it to a Au-based screen-printed electrode module (SPE) for
OTA determination. The signal probe, containing a structural covalent
organic framework, gold nanoparticles (AuNPs), indicative methylene
blue (MB), and a highly selective aptamer, is synthesized with hydrothermal
and self-assembly methods. The SPE is permanently functionalized with
Prussian blue (PB), AuNPs, and semicomplementary ssDNA. The signal
probe, absorbed onto this SPE via hybridization, is competitively
expelled by OTA, providing a ratiometric readout of ΔIMB/IPB. Probe regeneration,
to erase expired COF-Au-MB-Apt after each analysis, is established
with the synergy of OTA-conducted Apt-ssDNA dissociation and on-chip
thermal regulation. This advantage powerfully guarantees reduplicative
analyses by avoiding irreversible Apt-OTA combination and accumulation
on the sensing interface. Regenerations are performed in repetitive
cycles (N = 7) with 98.5% reproduction efficiency,
and IMB and IPB fluctuations are calculated as 1.45 and 1.12%. This method shows
log-linear OTA response in a wide range from 0.2 pg/mL to 0.6 μg/mL,
and the limit of detection is 0.12 pg/mL. During natural OTA determinations,
recommended readouts match well with HPLC with less than 4.82% relative
error.