Rapid and specific sensing of tetracycline in food using a novel upconversion aptasensor

- Developed a novel and high effective UCNPs aptasensor for detection of tetracycline.
- A good linearity and a low LOD of the UCNPs' biosensing platform was observed.
- This biosensor shows satisfactory performance for detection of targets in real samples.

Rare earth-doped upconversion nanoparticles (UCNPs) have a promising potential in biodetection due to their unique frequency upconverting capability and high detection sensitivity. This study developed a novel and sensitive aptamer-based UCNPs (NaY0.48Gd0.3F4:Yb0.2, Ho0.02) biosensor for sensing tetracycline (TET) in foodstuffs. The aptamer-magnetic nanoparticles (aptamer-MNPs) and the complementary DNA-UCNPs (cDNA-UCNPs) conjugates were prepared and used as the capture and signal probes, respectively. They formed the complex of MNPs-aptamer-cDNA-UCNPs with complete binding. With TET addition, the aptamer preferentially bound with TET and caused the dissociation of some cDNA; and the liberation of some cDNA-UCNPs. This led to a decreased fluorescent signal on the surface of MNPs. Under the optimal conditions, a wide linear detection range from 0.01 to 100 ng/mL was achieved, with a limit of detection of 0.0062 ng/mL, for detection of TET. The proposed method was successfully applied to measure TET in contaminated samples. Results showed that the proposed UCNPs biosensor offers an efficient, specific, and simple approach for the detection of TET in food, and has high potential for food safety and quality control.