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.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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