Split-type Assay for Wide-Range Sensitive Sensing of Ochratoxin A with Praseodymia Nanorods

The ubiquitous presence of ochratoxin A (OTA), a toxic food contaminant, requires development of fast and sensitive detection tools. However, it is difficult to find a method that can address high sensitivity and wide detection range simultaneously. In this work, a sensing platform composed of praseodymia nanorods (Pr6O11NRs) and aptamers for OTA is established. Under the dual-readout modes, this platform provides a highly sensitive detection of OTA with extra-wide range, over three orders of magnitude with limit of detection (LOD) of 0.8 ng/mL. Both fluorometric and colorimetric signals were obtained because of the excellent fluorescent quenching and oxidase-like activity of Pr6O11-NRs. This probe enables a detection range of OTA which covers the maximum acceptable levels of most foods. Real samples were tested with this method, demonstrating high sensitivity and good recoveries. This sensing strategy has great potential for an expanded application in point-ofcare detection of other toxins via portable devices.