A colorimetric aptasensor based on NH2-MIL-88B for highly selective detection of trace oxytetracycline in water

Abstract

Oxytetracycline (OTC) residues in the environment seriously endanger ecosystems and human health. Hence, it is critical to develop a selective and sensitive sensor for trace OTC detection. In this work, a facile and highly selective colorimetric aptasensor was constructed for OTC detection by the surface electrostatic assembly between aptamers and Fe-MOFs. Due to the steric effects and the decrease in the electron transfer rate, the peroxidase-like activity of NH₂-MIL-88B was significantly inhibited after the adsorption of aptamers. Furthermore, the selective binding between aptamers and OTC triggered the release of aptamers from the surface of NH₂-MIL-88B, which led to the reactivation of peroxidase-like activity. The colorimetric aptasensor exhibited a satisfactory detection range (1.0 × 10⁻¹⁰ M to 3.0 × 10⁻⁷ M) and the limit of detection (LOD) was as low as 1.9 × 10⁻¹¹ M. Additionally, the colorimetric aptasensor was successfully used to detect OTC in real samples. The developed colorimetric aptasensor provided an important reference value for the sensitive detection of other antibiotics in the environment.