Deep eutectic solvent-assisted synthesis of La–Ce hybrid nanorods for the colorimetric determination of tetracycline in foods

Abstract

Tetracycline (TC) as a broad-spectrum antibiotic, is widely used in the prevention and treatment of various bacterial diseases. However, its abuse in the livestock industry may lead to interference in human microecology, thereby causing various side effects. In this study, deep eutectic solvents (DESs) were synthesized using L-(–)-threonine (L-(–)-Thr) and cerium nitrate hexahydrate (Ce(NO₃)₃·6H₂O), and later lanthanum nitrate hexahydrate (La(NO₃)₃·6H₂O) was doped to synthesize La–Ce hybrid nanorods. These nanorods can be used for the determination of TC with high sensitivity and selectivity by the colorimetric method. This approach has a linear response to TC between 0.05 μM and 10 μM, with a detection limit of 0.016 μM. In this system, good dispersion provides the substance with a distinct peroxidase activity, which is used to create a colorimetric sensor for detecting TC. Mechanism studies show that the superoxide radical generated by the La–Ce nanomembrane plays a key role in peroxidase catalysis. Finally, the practicality of the method was verified by the determination of TC in food products (milk, pork and honey), which demonstrated that a good recovery rate can be obtained (91.4–102%).