Dual-emissive Eu(III)-functionalized metal-organic frameworks for visual, rapid, and intelligent sensing of albendazole and albendazole sulfoxide in animal-origin food.

Albendazole (ABZ), a benzimidazole-based anthelmintic, is widely used to treat helminth infections. The extensive and improper use of ABZ may cause drug residues in animal-origin food and anthelmintics resistance, which potentially threaten human health. Meanwhile, albendazole sulfoxide (ABZSO), a metabolite of ABZ, also exhibits toxic effects. Therefore, the detection of ABZ and ABZSO in animal-derived food is significantly necessary. Herein, a dual-emission europium fluorescent sensor (EuUHC-30) was rationally designed and constructed. EuUHC-30 exhibits high selectivity and sensitivity towards ABZ and ABZSO with a detection limit of 0.10 and 0.13 µM, respectively. Furthermore, EuUHC-30 was successfully applied for quantification of ABZ and ABZSO in milk and pig kidney, which were verified by HPLC analysis. Moreover, a smartphone-assisted EuUHC-30 fluorescent paper sensor was fabricated for the practical determination of ABZ and ABZSO in real food. Overall, this work provides a visual, rapid, and intelligent method for the detection of ABZ and ABZSO in animal-origin food.

A recyclable Eu3+-functionalized dual-emissive metal-organic framework for portable, rapid detection and efficient removal of malachite green.

A europium-functionalized, dual-emissive, metal-organic framework-based fluorescence sensor (EuUCNDA) was constructed via post-synthetic modification of an UiO-66-type precursor through coordination interactions. EuUCNDA exhibited extremely high selectivity and sensitivity for malachite green (MG) with a low detection limit of 13.01 nM, a wide linear concentration range (0.05-50 µM), excellent anti-interference properties, a rapid response (<1 min), and the possibility of recycling. The good sensing performance of EuUCNDA enables the practical detection of MG in fish pond water and grass carp with good recoveries. Moreover, EuUCNDA can be reused for sensing MG and over 90% of fluorescence intensity can be restored after 7 cycles. Furthermore, EuUCNDA-embedded paper-based sensors combined with smartphone imaging afford portable and visual monitoring of MG in real samples. Notably, besides good sensing performance, EuUCNDA could efficiently remove MG from water. Hence, this work provides a recyclable and sensitive fluorescence sensor for portable, visual, rapid detection and efficient removal of MG.

A highly water-stable dual-emission fluorescent probe based on Eu3+-loaded MOF for the simultaneous detection and quantification of Fe3+ and Al3+ in swine wastewater.

A novel dual-emissive Eu3+-loaded metal-organic framework (MOF) is designed and successfully fabricated by introducing 2-hydroxyterephthalic acid (H2BDC-OH) and Eu3+ ions into an UiO-66-type MOF material. The obtained MOF, here referred to as EuUCH, exhibits dual emission at 450 and 614 nm, and both emissions are quite stable in aqueous media in the pH range of 4-11. EuUCH is characterized by a high selectivity and sensitivity toward Fe3+ and Al3+, which yield different responsive modes. The two emissions of EuUCH are quenched by Fe3+; by contrast, only the emission at 450 nm is quenched by Al3+ showing a ratiometric fluorescence signal. More importantly, as there is no clear interference between the signals of Fe3+ and Al3+, EuUCH is successfully utilized for the simultaneous detection of Fe3+ and Al3+ in their mixtures. In addition, the simultaneous quantification of Fe3+ and Al3+ is achieved in more complicated swine wastewater with good recoveries. This work provides a water-stable dual-emissive probe and the possibility to achieve the simultaneous quantification of Fe3+ and Al3+ in complicated environment wastewater.

A luminescent Eu3+-functionalized MOF for sensitive and rapid detection of tetracycline antibiotics in swine wastewater and pig kidney.

Tetracyclines (TCs), a type of antibiotics, are widely used in human therapy and animal husbandry. Public concerns about tetracyclines residues have been raised due to their negative impact on the environment and food, causing bacterias drug resistance and human health concerns. In this work, a luminescent europium MOF (EuUCBA) is constructed via post-synthetic attachment of Eu3+ into a UiO-66 type MOF. The luminescent of EuUCBA exhibits high stability in aqueous media in the pH range of 4-11. Among 36 common veterinary drugs, the synthesized probe is highly selective and sensitive to six tetracyclines with low detection limits of 0.118 µM, 0.228 µM, 0.102 µM, 0.138 µM, 0.206 µM, and 0.078 µM for oxytetracycline (OTC), chlortetracycline (CTC), methylenetetracycline (MTC), minocycline (MOC), tetracycline (TC), and doxycycline (DOXY), respectively. Furthermore, the probe shows good anti-interference ability and fast response. Finally, EuUCBA was successfully to detect DOXY in swine wastewater and pig kidney with good recoveries. This work provides an excellent fluorescent sensor for highly selective and rapid detection of TCs residues in wastewater and complex biological samples.

Recyclable europium functionalized metal-organic fluorescent probe for detection of tryptophan in biological fluids and food products.

An europium functionalized metal-organic fluorescent probe, Eu3+@UiO-66-FDC was constructed by post-synthetic modification through coordination interactions. Eu3+@UiO-66-FDC displayed high selectivity and sensitivity toward Tryptophan (Trp) among all the 20 natural amino acids and other general compounds in food and biological samples, with a wide linear concentration range (0-1000 µM), low detection limit (0.29 µM), and a rapid response (<1 min). Besides, this probe was utilized to detect Trp in rabbit blood serum and milk samples with good recoveries, which were verified by high-performance liquid chromatography (HPLC). Notably, this fluorescent probe proved to be a recyclable material. Hence, this work provides a reliable and recyclable fluorescent probe applicable toward the detection of Trp in biological fluids and/or food products.

Highly sensitive and rapid detection of thiabendazole residues in oranges based on a luminescent Tb3+-functionalized MOF.

Thiabendazole (TBZ), has been extensively employed as a pesticide and/or a fungicide in agriculture, while its residues would threaten to public health and safety. Simple, rapid and sensitive probes for detection of TBZ in real food samples is significantly desirable. In present work, a highly selective and sensitive luminescent sensor for monitoring TBZ in oranges has been constructed based on a Tb3+-functionalized Zr-MOF (Tb3+@1). Tb3+@1 exhibited many attractive sensing properties toward TBZ, including broad linear range (0-80 µM), high selectivity, low LOD (0.271 µM) and rapid response time (less than1 min). Moreover, the probe was employed to determine TBZ in real orange samples, in which good recoveries from 98.41 to 104.48% were obtained. It only takes 35 min for the whole process of detection TBZ in real orange samples combined with QuEChERS method. Therefore, this work provided a reliable and rapid method for monitoring the TBZ in real orange samples.

Highly selective detection of Cu2+ in aqueous media based on Tb3+-functionalized metal-organic framework.

In this work, a metal-organic framework UiO-66-(COOH)2 has been synthesized and is further functionalized with Tb3+ through coordination interactions. The functionalized MOF, denoted as Tb3+@UiO-66-(COOH)2, is fully characterized and further developed as an excellent fluorescent probe to monitor Cu2+ ions in aqueous media by fluorescence quenching effect. Tb3+@UiO-66-(COOH)2 exhibits high selectivity and sensitivity, broad linear concentration range (0-200 µM), low detection limits (0.23 µM), fast response speed (within 1 min), as well as in situ naked eye observation under UV light for sensing Cu2+ ion. Furthermore, this probe was successfully employed to detect Cu2+ ion in real water with good recovery. Hence, this work developed a very excellent fluorescent sensor with high potential practical applications for detection of Cu2+ ion in environmental water samples.