Zr-MOF@Apt-mediated ratiometric fluorescence aptasensor for sensitive detection of capsaicin

Capsaicin serves as a specific marker for the identification of gutter oil. High-performance liquid chromatography (HPLC) is usually used to detect the capsaicin which is time-consuming and often fails to meet the detection requirements. Hence, establishing precise and swift methods for capsaicin detection is essential to safeguard food safety. In this study, a ratiometric fluorescence aptasensor (Zr-MOF@Apt) based on a zirconium-based nanoflower metal-organic framework (Zr-MOF) was innovatively constructed through the Zr-O-P bond for the high-sensitivity and high-selectivity detection of capsaicin. This aptasensor integrates the intrinsic advantages of both Zr-MOF and nucleic acid aptamers. The binding affinity of the Zr-MOF@Apt aptasensor for capsaicin was determined by isothermal titration calorimetry (ITC) experiment, with a Kd value of 111 ± 25.9 nM. The affinity of the aptasensor to capsaicin was much higher than that of free nucleic acid aptamers. Between 0.5 and 120 ng·mL −1 , the Zr-MOF@Apt aptasensor exhibited excellent linearity and a detection limit as low as 1.34 ng·mL −1 , achieving sensitive detection of capsaicin. This aptasensor has a low detection limit, high sensitivity and good stability, providing an important tool for accurately detecting harmful substances in food.