A Europium–Organic Framework Sensing Material for 2-Aminoacetophenone, a Bacterial Biomarker in Water

Abstract

2-Aminoacetophenone (2-AA) is a metabolite produced in large quantities by the pathogenic bacteria Pseudomonas aeruginosa (PA), which is a biomarker for PA in water. State-of-the-art analytical techniques to detect PA usually require expensive instruments and a long analysis time which are not suitable for real-time water quality monitoring, especially for high-quality drinking water. Herein, we reported the application of a europium metal–organic framework (Eu-MOF) as a luminescent sensing material, which provides a facile, environmentally friendly and low-cost way for the fast detection of PA in water. Eu-MOF shows a high sensitivity toward 2-AA with a K SV value of 3.563 × 104 M–1, rapid luminescence response in 12 s and high-selectivity and anti-interference ability with the existence of common detection indexes in drinking water owing to the good match of the energy levels of Eu-MOF and 2-AA. A systematical optimization of the sensing conditions to enhance the sensing function of Eu-MOF for 2-AA was discussed in detail, to give fundamentals for the rational design of MOF-based sensing materials.

Dual-Functional Metal–Organic Framework for Luminescent Detection of Carcinoid Biomarkers and High Proton Conduction

“…First, PXRD patterns and IR spectra of 1 after immersion in HT and HIAA solutions are similar to those of the as-synthesized 1 (Figures S1 and S5), indicating that the luminescence quenching does not result from decomposition of the framework. , Second, to further understand the quenching mechanism of the luminescence sensor, the luminescence lifetimes of 1 at 546 nm with and without HT and HIAA were measured. As seen in Figure S20 and Table S5, the luminescentce lifetimes of 1 displayed different degrees of decay after HT and HIAA were added, suggesting a dynamic quenching process should be responsible for the quenching effect. ,, As is known to all, luminescence quenching may also be attributed to the competitive absorption of the excitation light between sensors and analytes. , It can be observed that the absorption spectra of HT and HIAA displayed an obvious overlap with the absorption band of 1 , indicating the occurrence of a competitive absorption between 1 and the biomarkers. The irradiated light for 1 can be partially absorbed by HT and HIAA, diminishing the efficiency of energy transfer from ligands to the Tb III ion and subsequently leading to luminescence quenching.…”

“…First, PXRD patterns and IR spectra of 1 after immersion in HT and HIAA solutions are similar to those of the as-synthesized 1 (Figures S1 and S5), indicating that the luminescence quenching does not result from decomposition of the framework. 42,43 Second, to further understand the quenching mechanism of the luminescence sensor, the luminescence lifetimes of 1 at 546 nm with and without HT and HIAA were measured. As seen in Figure S20 and Table S5, the luminescentce lifetimes of 1 displayed different degrees of decay after HT and HIAA were added, suggesting a dynamic quenching process should be responsible for the quenching effect.…”

“…In recent years, the detection of biomarkers has become more and more important in health risk assessment and early diagnosis of diseases as well as monitoring in the process of treatment. − Among them, serotonin (5-hydroxytryptamine, HT), an inhibitory neurotransmitter in the central nervous system, at an abnormal level can cause a variety of diseases, including carcinoid, schizophrenia, migraine, anxiety disorder, Alzheimer’s disease (AD), and so on . Abnormalities of HT and its metabolite 5-hydroxyindole-3-acetic acid (HIAA) can be detected in the blood plasma or urine components of patients with malignant tumors; thus, HT and HIAA are regarded as discriminating biomarkers for the early detection of carcinoid tumors .…”

“…In order to achieve the luminescence sensing of HT and HIAA with high selectivity and sensitivity, the synergistic effects of multiple sensing mechanisms are conducive to achieving this goal. According to the mechanism of competitive absorption, an effective overlap between the UV–vis absorption spectra of the analytes and MOFs can achieve the selective detection of target analytes by luminescence quenching. ,,, At the same time, the process of energy transfer can also be affected by intermolecular interactions (hydrogen-bonding and π–π interactions) between the host and guest molecules, giving rise to higher sensitivity and a stronger luminescence quenching effect. , Together with the structural features of HT and HIAA, introducing π-conjugated systems with acidic groups such as −COOH, −SO 3 H, and −PO 3 H 2 is an alternative strategy. The uncoordinated acidic groups may form hydrogen-bonding interactions with the analytes, which can increase the effect of energy transfer and then improve the sensitivity of detection.…”

“…According to the mechanism of competitive absorption, an effective overlap between the UV−vis absorption spectra of the analytes and MOFs can achieve the selective detection of target analytes by luminescence quenching. 27,42,53,54 At the same time, the process of energy transfer can also be affected by intermolecular interactions (hydrogen-bonding and π−π interactions) between the host and guest molecules, giving rise to higher sensitivity and a stronger luminescence quenching effect. 55,56 Together with the structural features of HT and HIAA, introducing π-conjugated systems with acidic groups such as −COOH, −SO 3 H, and −PO 3 H 2 is an alternative strategy.…”