A sensitive and rapid sensing platform for ochratoxin A detection based on triple-helix molecular switch and CMC-EDC/NHS covalent immobilized paper

Ochratoxin A (OTA) is the most common mycotoxin contaminant that is widely distributed in food products. Herein, a sensitive and rapid sensing platform was constructed based on triple-helix molecular switch and CMC-EDC/NHS covalent immobilized paper. The aptamer-based triple-helix molecular switch (THMS) released signal transduction probe (STP) upon the addition of OTA, which was then enriched on the TR512-peptide function-alized paper modified with CMC-EDC/NHS chemistry. The sensing platform achieved a lower detection limit of 0.012 ng/mL with the linear range of 0.025-100 ng/mL. Notably, the sensing could be finished in less than 15.5 min without complex concentration process or expensive equipment. Additionally, the TR512-peptide based fusion protein was strongly-immobilized on the paper substrate via carbodiimide coupling, which prevented the fusion protein from leaching and enabled a large amount of solution molecules to bind with the fusion protein (up to 1 mL). Finally, a full-set of device was developed and applied in real samples with good accuracy. Taken together, the sensing platform integrating THMS with functionalized paper possesses practical application prospects in food samples and may offer a new protocol for the detection of multifarious target analytes by virtue of altering the aptamer sequence in THMS.