MXene–CeO2 Nanorod-Based Optical Biosensor for Ochratoxin A Detection in Real Food Samples

Ochratoxin A (OTA) is a potentially harmful mycotoxin that is widely found in agricultural products and animal by-products. In order to ensure our physical health, OTA testing is very important. Therefore, we chose to use an optical fiber biosensor based on the principle of local surface plasmon resonance (LSPR), and we designed an asymmetric optical fiber structure using single-mode optical fiber (SMF) to detect different concentrations of OTA. Gold nanoparticles (AuNPs) were applied to the sensing region to stimulate the LSPR effect, and then Nb 2 CTxMXene and CeO 2 -nanorods were sequentially fixed on the probe to change the dielectric environment around the sensing region to improve the performance of the sensor. The sensor has a linear range of 0.5 ng/mL to 60 ng/mL, a sensitivity of 0.0805 nm/(ng/mL), and a limit of detection (LOD) of 3.95 ng/mL. After that, we evaluated it through a series of tests, including repeatability, reproducibility, pH, stability, and selectivity. Finally, we also tested and verified the real samples. According to the experimental results, the sensor shows good performance in OTA detection, indicating that the sensor has good application potential and broad development prospects. This work designed an asymmetric optical fiber biosensor based on LSPR, achieving a broad detection range and a low LOD for OTA detection by coating with AuNPs, Nb 2 CTxMXene, and CeO 2 -nanorods. Its reliability and vast prospects in practical applications were validated through repeatability, stability, and real sample testing.