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The establishment of a reliable and sensitive method for the detection of flavonoids, such as kaempferol (Kae) and quercetin (Que), is important and challenging in food chemistry and pharmacology because numerous structural analogues may interfere with the detection. Until now, designing an efficient switch-on fluorescence sensing strategy for Kae and Que was still in the unachievable stage. In this work, a switch-on near-infrared (NIR) luminescence sensing assay for Kae and Que was fabricated based on a metal-organic framework (MOF) called IQBA-Yb for the first time. The fluorescence enhancing mechanism was that analytes served as additional "antenna" of Yb 3+ , leading to the efficient switch-on NIR emission under excitation at 467 nm. Meanwhile, the combination results of experiment and theoretical calculation revealed that there existed hydrogen bonds between Kae, Que, and the MOF skeleton, further promoting the energy transfer between the analyte and Yb 3+ and facilitating fluorescence enhancement response. The developed probe possessed excellent sensing capability for Kae and Que, accompanied by a wide linear range (0.04-70, 0.06-90 μM), low detection limit (0.01, 0.06 μM), and short response time (20 min, 6 min), which was used to determine the Kae and Que contents in Green Lake and eatable Que samples with satisfactory results.

The development of analytical method for selective and sensitive detection of gossypol (Gsp), an extraction from the cotton plants, is important but still challenging in food safety and medical field. Herein, we reported a turn-on near infrared (NIR) fluorescence detection strategy for Gsp based on a metal-organic framework (MOF), QBA-Yb, which was prepared from 4,4'-(quinolone-5, 8-diyl) benzoate with Yb(NO 3 ) 3 ·5H 2 O by solvothermal synthesis. The Gsp acted as another "antenna" to sensitize the luminescence of Yb 3+ , leading to the turn-on NIR emission upon 467 nm excitation. As Gsp concentration increased, the NIR emission at 973 nm enhanced gradually, thus enabling highly sensitive Gsp detection in a turn-on way. The experiment and theoretical calculation results revealed the presence of strong hydrogen bonds between Gsp molecules and the MOF skeleton. The developed QBA-Yb probe showed excellent characteristics for detection of Gsp molecules, accompanied by wide linear range (5-160 μg/mL), low detection limit (0.65 μg/mL) and short response time (within 10 min). We have further demonstrated that the QBA-Yb probe was successfully applied for the determination of Gsp in real samples of cottonseeds., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Rational design of controllable drug release systems is important for tumor treatments due to the nonspecific toxicity of many chemotherapeutics. Herein, laser or light responsive pharmaceutical delivery nanoparticles are designed, by taking the advantages of redox responsive selenium (Se) substituted polymer as shell and photosensitive porphyrin zirconium metal-organic frameworks (MOF) as core. In detail, redox cleavable di-(1-hydroxylundecyl) selenide (DH-Se), biocompatible poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) are randomly polymerized to form poly(DH-Se/PEG/PPG urethane), which is used to coat the reactive oxygen species' (ROS) producible porous porphyrin zirconium metal organization formulation (PCN-224 MOF) to form the final poly(DH-Se/PEG/PPG urethane)@MOF shell-core nanoparticle with spherical shape by emulsion approach. Interestingly, poly(DH-Se/PEG/PPG urethane)@MOF nanoparticles with loading of chemotherapeutic doxorubicin (DOX) experience a fast and controllable release, which can realize the combination of chemotherapy and photodynamic therapy upon irradiation with laser light, due to the light-triggered ROS production by MOF which further causes the cleavage of poly(DH-Se/PEG/PPG urethane) polymer chain and the release of encapsulated DOX. To the best of the authors' knowledge, this is the first design of utilizing MOF and selenium substituted polymer as controllable drug release carriers, which might be beneficial for precise chemotherapy and photodynamic therapy combination., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Covalent organic frameworks (COFs) are a class of crystalline porous materials utilized in various potential applications. However, the development of hollow-structured COFs with defined morphology is important for their further applications, which is rare. Herein, COF with unique hollow shuttle morphology was prepared by a Schiff condensation reaction between 4-(4-aldehyde phenyl)ethylene (TPE) and tetra-(4-aminophenyl) porphyrin (TAP). A detailed mechanistic investigation reveals that an initial self-assembly followed by a similar inside-out Ostwald ripening process is responsible for the hollow capsule formation. The hollow microshuttle-shaped capsule COF is used for studying hemoglobin adsorption, which shows an uptake of 550.82 mg g -1 of hemoglobin. These studies could foreshadow new avenues for the development of porous materials with defined morphologies for the adsorption of biomolecules.

Metal–organic framework (MOF) materials with aqueous stability have a good potential application in the field of mimetic enzymes. However, most of them have poor robustness in aqueous solution due to competitive coordination effects between water molecules and central metal ions. Herein, a copper-based MOF (Cu-SM MOF) was prepared using copper ions and 5-(sulfomethyl) isophthalic acid (5-SMIPA) by a hydrothermal process. Considering the similarity of coordination and morphology with HKUST-1, the aqueous stability and laccase-like activity of the Cu-SM MOF were investigated using HKUST-1 as the reference. The Cu-SM MOF shows superior aqueous stability to HKUST-1 after immersion in buffer solutions, especially under alkaline conditions. Moreover, the Cu-SM MOF possesses higher catalytic activity than HKUST-1 at a high salt concentration, high temperature, etc., because the Cu-SM MOF exhibits lower Km and higher Vmax values than those of laccase and reported mimetic enzymes. The mimetic enzyme behavior of the Cu-SM MOF is demonstrated in the oxidation of phenols, as well as in the detection of 2,4-dichlorophenol (2,4-DP) and p-nitrophenol with linear ranges of 1–100 μM and 2–250 μM, and limits of detection of 0.53 μM and 1.62 μM, respectively. Owing to the excellent aqueous stability and laccase-like activity of the Cu-SM MOF, it has great application prospects in many fields, such as the determination of phenols and the treatment of industrial wastewater. [ABSTRACT FROM AUTHOR]

The YNU-1 nanobelts possessing abundant free carboxyl groups was applied for wastewater treatment of Fe3+, which exhibited highest adsorption capacity of 456.37 mg/g among all previous adsorbents. • Most adsorbents own poor adsorption performance due to the less binding sites. • 2D MOFs possess more unsaturated coordination centers and accessible active sites. • YNU-1 nanobelts can be obtained facilely by immersing YNU-1 crystals in water. • YNU-1 nanobelts showed an excellent adsorption performance for Fe3+. Ultrathin metal-organic frameworks (MOFs) have emerged as a novel class of two-dimensional materials for their unique properties, such as the larger surface area, enriched unsaturated coordination centers and more accessible active sites, which are beneficial for improving their performances in catalysis, sensing and separation. In this work, the MOF (named YNU-1 nanobelts) was exploited to selectively remove Fe3+ from aqueous solutions, which showed an excellent adsorption performance with the adsorption capacity of 456.37 mg/g. The value is the highest among all reported adsorbents of Fe3+, owing to the coordination between the Fe3+ and abundant carboxyl groups on the surface of YNU-1 nanobelts. The adsorption behavior can be well-described with a pseudo-second-order kinetic model, which revealed a chemisorption process. The α-Fe 2 O 3 on the surface of YNU-1 nanobelts after adsorption was confirmed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and element mapping measurements. The YNU-1 nanobelts was successfully applied for iron treatment in real sample. Our study provided a facile and efficient method for the removal of iron ions from water. [ABSTRACT FROM AUTHOR]