Ratiometric fluorescence aptasensor for the detection of patulin in apple juice based on the octahedral UiO-66-TCPP metal-organic framework and aptamer systems

Patulin (PAT) is a potentially harmful mycotoxin to human health and is known to contaminate apple juice. In this work, we developed a ratiometric fluorescence aptasensor using tetrakis(4-carboxyphenyl)porphyrin (H 2 TCPP)-treated octahedral UiO-66-NH 2 (defined as UiO-66-TCPP) to detect PAT. This 2-aminoterephthalic acid and H 2 TCPP functionalized metal-organic framework showed multiple adsorption effects (hydrogen bonding and π–π stacking) on the aptamer (Apt) and served as a quenching material. When the target PAT bound specifically to the Apt, the fluorescence of the 6-carboxyfluorescein-labeled Apt would recover, and the fluorescence of the H 2 TCPP ligand remained unchanged. This ratiometric fluorescence property improved the accuracy of PAT detection. Moreover, the introduction of the H 2 TCPP ligand enhanced the quenching efficiency of UiO-66-NH 2 , thus improving the sensitivity of the fluorescent aptasensor (UiO-66-TCPP vs. UiO-66-NH 2 : 0.0162 ng/mL vs. 1.8 ng/mL). In addition, we used UiO-66-TCPP to detect PAT in apple juice samples. This work provides a good paradigm for the construction of ratiometric fluorescence aptasensors with high sensitivity and accuracy.