Analyte-induced enhancement of oxidase-like activity of cerium-based metal-organic frameworks for "turn-on" detection of 2-amino-3-methylimidazo[4,5-f]quinoline.

Heterocyclic aromatic amines (HAAs), formed during the thermal processing of meat, are a group of carcinogenic and mutagenic compounds that pose significant risks to food safety and human health. Among them, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) is considered one of the most hazardous substances, making its monitoring critically important. However, conventional detection techniques are often limited by sophisticated and costly instruments, complex operation process, and highly trained personnel. In this study, we proposed a "turn-on" colorimetric sensing strategy for the detection of IQ based on the analyte-triggered enhancement of oxidase-like activity of Ce-UiO-66 nanozyme. Ce-UiO-66 was synthesized using a simple solvothermal method via the self-assembly of terephthalic acid and Ce4+ ions. The resulting Ce-UiO-66 exhibited excellent oxidase-like activity, catalyzing the oxidation of 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) via the generation of superoxide anions from oxygen. In the presence of IQ, electrostatic interactions facilitated the rapid adsorption of IQ onto the negatively charged Ce-UiO-66 surface, reversing the surface charge to positive. This charge shift enhanced the affinity of Ce-UiO-66 for negatively charged ABTS, significantly accelerating its oxidation. Based on this principle, we established a "turn-on" colorimetric sensing strategy for the detection of IQ, achieving a detection limit of 5.41 μM. This Ce-UiO-66 nanozyme-based detection method demonstrated high selectivity and anti-interference performance and could efficiently distinguish its analog 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in complex food matrices. Further experimental data illustrated that this strategy was successfully applied to the detection of IQ in roasted meat samples. This work might offer a simple, cost-effective, and robust approach for rapid screening of IQ in highly contaminated processed meats.