Mannose-engineered Eu-MOF for ratiometric fluorescent/colorimetric dual-detection and inhibition of E. coli.

A ratiometric fluorescence sensor based on Eu3+@tetrafluorosuccinic acid functionalized UiO-67: Enhancing the detection performance of ofloxacin through pre-concentration effect.

The excessive use of ofloxacin (OFL) has led to its persistent residues in water sources and animal-derived foods, posing a threat to human health. Therefore, it is urgent to develop fluorescent sensing materials capable of detecting ofloxacin in water environments and food matrices. Herein, a novel Eu3+@tetrafluorosuccinic acid-functionalized ratiometric fluorescent material Eu3+@UiO-67-TFSA was prepared by a two-step post-synthetic modification of UiO-67. In the concentration range of 1-15 μM, the Eu3+@UiO-67-TFSA had a limit of detection (LOD) of 0.42 μM for OFL, which was approximately 3.90 times lower than that of the non-fluorinated Eu3+@UiO-67-SA (LOD = 1.64 μM). The improved sensing performance could be attributed to the pre-concentration effect provided by the Eu3+@UiO-67-TFSA. The possible detection mechanism was systematically elucidated through relevant experiments and density functional theory (DFT) calculation. Moreover, the constructed smartphone-assisted visual sensing platform was successfully applied to detect OFL in actual food samples and real water environment samples.

Pt@Fe-MIL-88 Enabled Natural-Enzyme-Free Dual-Mode Assay for Highly Selective Detection of Glyphosate.

Compared with natural-enzyme-based detection strategies, nanozymes offer notable advantages in stability, environmental tolerance, and cost-effectiveness. In this study, we designed and synthesized a Pt@Fe-MIL-88 composite with both oxidase (OXD)-like activity and intrinsic fluorescence. The material efficiently catalyzes 3,3',5,5'-tetramethylbenzidine (TMB) oxidation, generating a color change while quenching its fluorescence. Glyphosate (Gly) specifically inhibits the OXD-like activity of Pt@Fe-MIL-88, reducing oxTMB production and thereby alleviating fluorescence quenching, enabling dual colorimetric and fluorometric signal readout. The inhibition mechanism was elucidated through FTIR, XRD, XPS characterization, molecular dynamics simulations, and DFT calculations. Accordingly, a natural-enzyme-free, colorimetric-fluorometric dual-mode sensing platform for Gly was established. The platform exhibits high sensitivity, excellent selectivity, and strong anti-interference capability, with accuracy and reliability validated by spike recovery tests in real samples. This work presents a new strategy for developing stable, rapid, and low-cost multimodal detection methods for pesticide residues.

Carambola-like metal-AIEgen framework-based fluorescent lateral flow assay for the sensitive detection of zearalenone

Engineering a Mn3O4/Eu MOF nanocomposite for ratiometric dual-mode sensing: mechanistic insight and ultrasensitive detection of nitrite in complex food matrices.

Rapid, sensitive, and reliable detection of nitrite remains a critical analytical challenge, given its importance for food safety and public health. Herein, we report a dual-mode, dual-ratiometric colorimetric-fluorescent sensor based on a Mn3O4/Eu-MOF hybrid for the ultrasensitive detection of nitrite. The Mn3O4 component exhibits prominent oxidase-mimicking activity and can rapidly catalyze the oxidation of TMB to its blue oxidized product, ox-TMB. Owing to the highly specific diazotization reaction between nitrite and ox-TMB under acidic conditions, the blue reaction solution gradually fades, accompanied by the formation of a yellow diazotization product. This process generates a characteristic ratiometric colorimetric response, manifested by a marked decrease in absorbance at 652 nm and a simultaneous increase at 450 nm. Meanwhile, ox-TMB quenches the red emission of Eu3+ at 615 nm via the inner filter effect. Upon nitrite addition, consumption of ox-TMB restores Eu3+ fluorescence, whereas the ligand emission at 360 nm remains essentially unchanged, enabling built-in ratiometric fluorescence self-calibration. Together, these two sensing modes provide an ultrawide linear range of 0.2-55 μg·mL-1 and low detection limits of 0.095 μg·mL-1 for colorimetry and 0.084 μg·mL-1 for fluorometry, meeting regulatory requirements for nitrite in drinking water and meat products. Practical application in sausage, pickled vegetable, tap water, and lake water samples shows excellent agreement with the Griess method, with relative deviations below 5%, recoveries ranging from 93.27% to 101.09%, and RSDs below 3.5%. This Mn3O4/Eu-MOF platform therefore enables simple, sensitive, and reliable on-site nitrite detection and offers a general strategy for constructing multifunctional MOF-based dual-ratiometric sensors.

Amino-Acid/Protein-Engineered Zr/Ce-MOF Nanozyme for Dual-Channel Smart On-Site Detection of Tetracyclines and d -Penicillamine

The threat of drug residues drives an urgent demand for shifting from centralized laboratory testing to point-of-need intelligent diagnostics. Herein, we construct a smartphone-regulated sensing platform that integrates a wavelength-programmable dual-light source module with a custom-developed “FluoChroma X” App for parallel dual-channel monitoring of tetracycline antibiotics (TCs) and d-penicillamine (d-PA). The core of this system is a hierarchical bio-nanostructured sensor consisting of an arginine/histidine-modulated zirconium/cerium bimetallic organic framework conjugated with bovine serum albumin (BSA) and designated as ZCDA@Arg@His. TCs quench the intrinsic blue emission of ZCDA@Arg@His through inner filter effect and photoinduced electron transfer, while the BSA-confined microenvironment restricts the intramolecular rotation of TCs, triggering intense aggregation-induced green luminescence for high-fidelity ratiometric sensing. The ratiometric sensor array achieves 100% classification accuracy for structurally analogous TCs using machine learning algorithms. In addition, arginine and histidine cooperatively regulate the Ce4+/Ce3+ redox microenvironment by promoting substrate-active-site interactions and metal-site coordination, thereby enhancing the metalloenzyme-mimicking activity of ZCDA@Arg@His to catalyze the chromogenic cascade reaction, while d-PA acts as a radical scavenger to interrupt the colorimetric process. The sensing platform exhibits unprecedented analytical performance with limits of detection as low as 3.9 nmol·L−1 for TCs and 0.31 μmol·L−1 for d-PA. This work is validated across multiple food matrices and establishes a machine learning-assisted, structurally constrained biophotonic strategy for broad-scale, high-throughput monitoring.

Multiemission Ln-MOF Fluorescence Sensing Array for Identification of Antibiotic Residues in Environmental and Food Samples.

The environmental residues and drug resistance resulting from antibiotic abuse urgently call for the development of efficient multicomponent detection technologies. Therefore, single-lanthanide metal-organic frameworks [Ln(BDPO)(H2O)4](H2O) (DMF): Ln = Eu, Tb, Gd, Dy; BDPO= N,N'-bis(3,5-dicarboxyphenyl)-oxalamide are designed and synthesized, and the ternary mixed-metal MOFs are constructed. Single-crystal X-ray diffraction analysis shows that the series MOFs belong to the triclinic P1̅ space group with a one-dimensional chain structure. Optical performance tests confirm that Eu-MOF and Tb-MOF exhibit ligand-to-rare-earth ion ″antenna effect″ that allows for dual-emission ratio fluorescence response. Based on this, Eu-MOF and Tb-MOF exhibit high sensitivity and quantitative detection capabilities for ciprofloxacin and ofloxacin. The multiemission centers of EuTbGd-MOF show differential responses identify seven types of antibiotics when combined with linear discriminant analysis (LDA), principal component analysis (PCA), and hierarchical cluster analysis (HCA). Real sample testing demonstrate that the sensor array can effectively identify target antibiotics even in milk and tap water matrices. This study provides a new sensing platform for the highly selective detection of multicomponent pollutants in complex systems, offering significant application prospects in environmental monitoring and food safety.