Rapid Detection of Ochratoxin A in Corn Using a Digoxin-Modified Aptamer-Based Lateral Flow Test Strip

To establish a rapid and sensitive method for detecting ochratoxin A (OTA), a lateral flow test strip was developed using a gold nanoparticle-c DNA conjugate (Au NPs-SH-c DNA) by a freezing method as the detector probe on the conjugate pad as well as using anti-digoxin monoclonal antibodies as the test line and aptamers as the control line on the nitrocellulose membrane. Digoxin-modified aptamers (Dig-Apt) were used as recognition elements for binding to OTA in the loading buffer. Under optimal conditions, the limit of detection (LOD) of the method was 0.3 ng/mL, and the half-maximal inhibitory concentration (IC₅₀) was 12.5 ng/mL. The recoveries in spiked corn samples ranged from 100.82% to 106.30%, with coefficients of variation between 2.54% and 6.78%, a false positive rate ≤ 0% and a false negative rate ≤ 1%. The developed test strip provides an effective method for detecting OTA in corn, demonstrating promising application potential.