UiO-67 decorated on porous carbon derived from Ce-MOF for the enrichment and fluorescence determination of glyphosate

Iron-ferrocenedicarboxylic nanozyme based colorimetric and photothermal dual-modal signal catalytic inhibition for detection of glyphosate

A novel dual-mode colorimetric and photothermal sensing platform for glyphosate (GLP) based on iron-ferrocenedicarboxylic metal-organic framework (Fe-FcMOF) nanozyme-mediated catalysis is presented. Specifically, the synthesized Fe-FcMOF nanozyme exhibits superior peroxidase (POD)-like activity, which can oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxidized TMB (ox TMB) in the presence of H2O2. Due to the photothermal effect of oxTMB, the catalytic system composed of Fe-FcMOF, H2O2 and TMB exhibits remarkable temperature changes (ΔT) before and after being irradiated by near-infrared light at 808 nm. Subsequently, Fe-FcMOF reacts with GLP through electrostatic attraction, hydrogen bonding and specific chemical coordination between the -FeO of Fe-FcMOF and -PO3H2 of GLP, resulting in the formation of stable Fe-O-P coordination bonds. This specific interaction leads to the decrease of the POD-like activity of Fe-FcMOF and the ultraviolet absorbance and ΔT of the system. Building upon these findings, we develop a colorimetric and photothermal dual-modal sensor, with detection limits of 0.0676 µg mL-1 and 0.0856 µg mL-1 respectively. Notably, the proposed dual-mode sensing platform enhances the reliability of the assay, which offers a potential approach for the on-site visual detection of pesticide residues to guarantee food safety.

In-situ preparation of CeO2@MIL-88B nanocomposite for improving "turn-on" fluorescent sensing toward Thiabendazole

A novel "turn-on" fluorescent sensor of CeO2@MIL-88B was constructed successfully via the facile in-situ strategy. The as-obtained CeO2@MIL-88B could be used for effectively detecting the analyte of thiabendazole (TBZ) by luminescence enhancement, which limit of detection (LOD) was as low as 0.294 μM (nearly 10.4 times smaller than that of MIL-88B). The detection behavior for TBZ exhibited the excellent selectivity and anti-interference ability. Systematic explorations were performed to shed light on the underlying mechanism of "turn-on" effect on fluorescence after adding TBZ. Moreover, the CeO2@MIL-88B was also employed for the determination of TBZ in the real samples of orange and cucumber.

Collaboratively removal of phosphate and glyphosate from wastewater by a macroscopic Zr-SA/Ce-UIO-66 adsorbent: Performance, mechanisms and applicability

Dissolved inorganic and organic phosphorus is a major factor in triggering the eutrophication of water bodies. At present, a novel Zr4+ cross-linked sodium alginate encapsulated in Ce-UIO-66 microspheres (Zr-SA/Ce-UIO-66) was prepared and systematically characterized. Its ability for capture of phosphate and glyphosate in their single and binary systems has been investigated comprehensively. Results showed that Zr-SA/Ce-UIO-66 exhibits excellent phosphate adsorption, achieving 92 % removal and a maximum adsorption capacity of 125 mg P/g at 313 K. Diversified mechanisms, including electrostatic attraction, ligand exchange and hydrogen bonding, have cooperatively participated in phosphate removal. Interestingly, in phosphate and glyphosate mixed solutions, the presence of phosphate significantly enhanced the removal of glyphosate for the formation of complexes between phosphate ions and the adsorbent. And that was similar to the presence of glyphosate in phosphate adsorption. Simulated wastewater experiments demonstrated the adsorbent's practical application in water contaminated with both organic phosphorus and glyphosate composites and its potential for recycling and reuse.

Bifunctional MOFs Nanozyme with Peroxidase Activity and Stimulus-responsive Fluorescent for Determination of Glyphosate

Establishing a fast and simple method for determining glyphosate (Glyp) is crucial for safeguarding the environment and protecting human well-being. In this work, a copper benzenedicarboxylate (CuBDC) metal-organic frameworks (MOFs) with peroxidase-like property and stimulus-responsive fluorescent was prepared by binding Cu2+ with terephthalic acid (TA). The presence of Glyp can coordination with Cu2+ ion and block the peroxidase-like properties of CuBDC, thereby suppressing the catalysis the oxidation of TA into fluorescent product 2-hydroxyterephthalic acid (HTA). Based on these facts, a simple, rapid and sensitive fluorescence detection strategy for Glyp was developed. The fluorescence decreases linearly in the 0.5-10 µg/mL Glyp concentration range, and the limit of detection was calculated to be 23.99 ng/mL. Furthermore, the dual-functional CuMOFs-based label-free strategy was effectively employed for detecting Glyp in river water samples. With good performance and practicability, this strategy provides a potential application in the convenient and reliable determination of Glyp in the environment.

Harnessing the UiO-67 metal-organic framework for advanced detection of cadmium ions in water bodies

Heavy metal ions are hazardous pollutants that pose serious threats to ecosystems and human health, making it imperative to detect and monitor their presence in water for environmental protection. This paper highlights the synthesis of the UiO-67 Metal-Organic Framework (MOF) without any dopants, offering a novel approach specifically for the detection of cadmium ions (Cd2+) in aqueous environments. Following solvothermal synthesis, Powder X-ray Diffraction (PXRD), BET nitrogen adsorption-desorption analysis, X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM) were used to characterize the structural and morphological features of UiO-67. The MOF exhibited a high pore volume and surface area, which are essential for enhancing its detection capabilities for Cd2+ ions. Based on experimental findings, the proposed sensor exhibits excellent selectivity towards Cd2+ ions and a sensitivity of 3.008 μA nM-1. Further, it achieves a low Limit of Detection (LoD) of 1.43 nM μA-1 and a Limit of Quantification (LoQ) of 4.34 nM μA-1. The sensitivity and reliability of the UiO-67-modified electrode are demonstrated by these values, which qualify it for trace-level cadmium ion detection. The ground-breaking potential of undoped UiO-67 serves as a cutting-edge and effective tool for environmental monitoring, particularly in the detection of toxic metal ions in water bodies.

An exceptional water stable terbium-based metal-organic framework for selective detection of pesticides

A terbium-based metal-organic framework (MOF) with exceptional water stability for highly selective detection of pesticide thiamethoxam (TMX) in aqueous solution is reported. To date, most reported lanthanide metal-organic frameworks (Ln-MOFs) still exhibit poor water stability, which may limit their practical applications in bio-sensing and detecting pollutants in environmental water samples. In this work, a Tb-MOF [Tb(BDC)1.5(DEF)·0.5H2O] n (1, BDC = 1,4-benzene dicarboxylate, DEF = N,N-diethylformamide) was prepared by hydrothermal reactions of 1,4-benzenedicarboxylic acid with the corresponding rare earth ions of Tb3+. Impressively, water stability surveys of compound 1 indicated that it maintained at least 90% of its emission intensity after storage in water for several months. This characteristic of long water stability is unusual as compared to other Ln-MOFs, making compound 1 an excellent candidate for sensing applications in the aqueous phase. In particular, the green emission of compound 1 could be quenched by the pesticide thiamethoxam (TMX), which was attributed to both the static and dynamic quenching processes based on an upward-curving Stern-Volmer plot. The quenching mechanism was speculatively attributed to the inner filter effect combined with the complex formation based on the electrostatic interaction of compound 1 and TMX, resulting in the promotion of the quenching efficiency. Finally, compound 1 was demonstrated to detect TMX in aqueous solution with rapid response and high selectivity.

Fluorescent chemosensors facilitate the visualization of plant health and their living environment in sustainable agriculture

Globally, 91% of plant production encounters diverse environmental stresses that adversely affect their growth, leading to severe yield losses of 50-60%. In this case, monitoring the connection between the environment and plant health can balance population demands with environmental protection and resource distribution. Fluorescent chemosensors have shown great progress in monitoring the health and environment of plants due to their high sensitivity and biocompatibility. However, to date, no comprehensive analysis and systematic summary of fluorescent chemosensors used in monitoring the correlation between plant health and their environment have been reported. Thus, herein, we summarize the current fluorescent chemosensors ranging from their design strategies to applications in monitoring plant-environment interaction processes. First, we highlight the types of fluorescent chemosensors with design strategies to resolve the bottlenecks encountered in monitoring the health and living environment of plants. In addition, the applications of fluorescent small-molecule, nano and supramolecular chemosensors in the visualization of the health and living environment of plants are discussed. Finally, the major challenges and perspectives in this field are presented. This work will provide guidance for the design of efficient fluorescent chemosensors to monitor plant health, and then promote sustainable agricultural development.

A dual-responsive RhB-doped MOF probe for simultaneous recognition of Cu2+ and Fe3

Based on the dual response of RhB@UiO-67 (1:6) to Cu2+ and Fe3+, a proportional fluorescent probe with (I392/I581) as the output signal was developed to recognize Cu2+ and Fe3+. Developing highly sensitive and selective trace metal ions probes is crucial to human health and ecological sustainability. In this work, a series of ratio fluorescent probes (RhB@UiO-67) were successfully synthesized using a one-pot method to enable fluorescence sensing of Cu2+ and Fe3+ at low concentrations. The proportional fluorescent probe RhB@UiO-67 (1:6) exhibited simultaneous quenching of Cu2+ and Fe3+, which was found to be of interest. Furthermore, the limits of detection (LODs) for Cu2+ and Fe3+ were determined to be 2.76 μM and 0.76 μM, respectively, for RhB@UiO-67 (1:6). These values were significantly superior to those reported for previous sensors, indicating the probe's effectiveness in detecting Cu2+ and Fe3+ in an ethanol medium. Additionally, RhB@UiO-67 (1:6) demonstrated exceptional immunity and reproducibility towards Cu2+ and Fe3+. The observed fluorescence quenching of Cu2+ and Fe3+ was primarily attributed to the mechanisms of fluorescence resonance energy transfer (FRET), photoinduced electron transfer (PET), and competitive absorption (CA). This work establishes a valuable foundation for the future study and utilization of Cu2+ and Fe3+ sensing technologies.

Glyphosate Separating and Sensing for Precision Agriculture and Environmental Protection in the Era of Smart Materials

The present article critically and comprehensively reviews the most recent reports on smart sensors for determining glyphosate (GLP), an active agent of GLP-based herbicides (GBHs) traditionally used in agriculture over the past decades. Commercialized in 1974, GBHs have now reached 350 million hectares of crops in over 140 countries with an annual turnover of 11 billion USD worldwide. However, rolling exploitation of GLP and GBHs in the last decades has led to environmental pollution, animal intoxication, bacterial resistance, and sustained occupational exposure of the herbicide of farm and companies' workers. Intoxication with these herbicides dysregulates the microbiome-gut-brain axis, cholinergic neurotransmission, and endocrine system, causing paralytic ileus, hyperkalemia, oliguria, pulmonary edema, and cardiogenic shock. Precision agriculture, i.e., an (information technology)-enhanced approach to crop management, including a site-specific determination of agrochemicals, derives from the benefits of smart materials (SMs), data science, and nanosensors. Those typically feature fluorescent molecularly imprinted polymers or immunochemical aptamer artificial receptors integrated with electrochemical transducers. Fabricated as portable or wearable lab-on-chips, smartphones, and soft robotics and connected with SM-based devices that provide machine learning algorithms and online databases, they integrate, process, analyze, and interpret massive amounts of spatiotemporal data in a user-friendly and decision-making manner. Exploited for the ultrasensitive determination of toxins, including GLP, they will become practical tools in farmlands and point-of-care testing. Expectedly, smart sensors can be used for personalized diagnostics, real-time water, food, soil, and air quality monitoring, site-specific herbicide management, and crop control.

A versatile platform for colorimetric, fluorescence and photothermal multi-mode glyphosate sensing by carbon dots anchoring ferrocene metal-organic framework nanosheet

Concerns regarding pesticide residues have driven attempts to exploit accurate, prompt and straightforward approaches for food safety pre-warning. Herein, a nanozyme-mediated versatile platform with multiplex signal response (colorimetric, fluorescence and temperature) was proposed for visual, sensitive and portable detection of glyphosate (GLP). The platform was constructed based on a N-CDs/FMOF-Zr nanosensor that prepared by in situ anchoring nitrogen-doped carbon dots onto zirconium-based ferrocene metal-organic framework nanosheets. The N-CDs/FMOF-Zr possessed excellent peroxidase (POD)-like activity and thus could oxide colorless 3, 3', 5, 5'-tetramethylbenzidine (TMB) into a blue oxidized TMB (oxTMB) in presence of H₂O₂. Intriguingly, owing to the blocking effect triggered by multiple interaction between GLP and N-CDs/FMOF-Zr, its POD-like activity of the latter was remarkably suppressed, which can modulate the transformation of TMB into oxTMB, generating tri-signal responses of fluorescence enhancement, absorbance and temperature decrease. More significantly, the temperature mode can be facilely realized by a portable home-made mini-photothermal device and handheld thermometers. The proposed multimodal sensing was capable of providing sensitive results by fluorescence mode and simultaneously realized visual/portable testing by colorimetric and photothermal channels. Consequently, it exhibited more adaptability for practical applications, which can satisfy different testing requirements according to sensitivity and available instruments/meters, presenting a new horizon for exploiting multifunctional sensors.

Green synthesized Ag decorated CeO2 nanoparticles: Efficient photocatalysts and potential antibacterial agents

Implication of natural resources for manufacturing of nanoparticles is sustainable, economical and contaminant free approach towards ecological and medical applications. Herein, CeO₂ and Ag/CeO₂ nanoparticles are green synthesized from Morinda tinctoria plant extract. The phase structure, surface morphology, optical identity, Ce(III) and Ce(IV) valency of the synthesized CeO₂ and Ag/CeO₂ nanoparticles are explored. The X-ray diffraction analysis indicated the formation of cubic phase CeO₂ and cubic silver decorated CeO₂ nanoparticles. Fourier transform infrared (FTIR) spectroscopy revealed the metal decoration of CeO₂ nanoparticles, metal-oxygen stretching, indicating the plant molecules reduction and stabilization. UV-visible spectroscopy shown the decreased band gap owing to silver modification. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs displayed spherical morphology of the nanoparticles. Elemental composition and sample purity is assessed by energy dispersive spectroscopy (EDS). Double oxidation of Ce, double splitting energy of Ag and lattice oxygen are observed from X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of Ag/CeO₂ exposed the enhanced photocatalytic activity up to 94% where CeO₂ nanoparticles gave 60% degradation of bromophenol blue (BB). The plasmonic decoration of silver on the ceria surface induced the charge separations and free radical reactions. Moreover, Ag/CeO₂ nanoparticles are seen as superior antibacterial agents than CeO₂ towards both E.coli and S.aureus. Hence, the silver decorated metal oxide photocatalyst successfully degraded the BB dye and inactivated the bacterial strains. This report established a future research in green synthesis of multipurpose metal nanoparticles.

An Overview of the Design of Metal-Organic Frameworks-Based Fluorescent Chemosensors and Biosensors

Taking advantage of high porosity, large surface area, tunable nanostructures and ease of functionalization, metal-organic frameworks (MOFs) have been popularly applied in different fields, including adsorption and separation, heterogeneous catalysis, drug delivery, light harvesting, and chemical/biological sensing. The abundant active sites for specific recognition and adjustable optical and electrical characteristics allow for the design of various sensing platforms with MOFs as promising candidates. In this review, we systematically introduce the recent advancements of MOFs-based fluorescent chemosensors and biosensors, mainly focusing on the sensing mechanisms and analytes, including inorganic ions, small organic molecules and biomarkers (e.g., small biomolecules, nucleic acids, proteins, enzymes, and tumor cells). This review may provide valuable references for the development of novel MOFs-based sensing platforms to meet the requirements of environment monitoring and clinical diagnosis.