“Green” one-pot synthesis of hemin complex with excellent peroxidase activity: Efficient enhanced chemiluminescence immunosensor for ultrasensitive detection of ochratoxin A

Compared with natural enzymes, nanozymes have the advantages of easy preparation, low cost and high stability. With the booming development of nanozymes, scientists have further defined them as "nanomaterials with enzyme-like properties". Here, on the one hand, ZIF-L has the characteristics of simple preparation, good stability and large specific surface area. Meanwhile, the array structure of Zn2+ and imidazole in the ZIF-L can replace the amino acids precisely located in the natural enzymes, thus mimicking the microenvironment of the natural peroxidase. On the other hand, based on the chemical similarity of hemin to natural heme, we encapsulated hemin into the ZIF-L backbone by a straightforward "green" one-pot technique. According to the symbiotic stability-enhancing effect, the encapsulated biomolecules can make the ZIF-L matrix more stable while the ZIF-L backbone protects the enzyme from denaturation. Whereupon. Based on this, ZIF-L-Hemin composites with excellent peroxidase properties was successfully prepared. Using ZIF-L-Hemin composites, we constructed a flow-injection chemiluminescence immunoassay for the quick and ultrasensitive detection of ochratoxin A (OTA) in food. The experimental results showed that the detection range of OTA was 0.0015 ∼ 1500 ng mL−1, and the limit of detection (LOD) was 0.47 pg mL−1 (S/N = 3). The OTA analysis of wheat, corn and feed samples showed that the recoveries ranged from 80.83 % to 115.54 %, which successfully demonstrated the usability and potential applications of immunosensor.