Preparation of iron-based MIL-101 functionalized polydopamine@Fe3 O4 magnetic composites for extracting sulfonylurea herbicides from environmental water and vegetable samples

Nanocomposites Based on Magnetic Nanoparticles and Metal-Organic Frameworks for Therapy, Diagnosis, and Theragnostics

In the last two decades, metal-organic frameworks (MOFs) with highly tunable structure and porosity, have emerged as drug nanocarriers in the biomedical field. In particular, nanoscaled MOFs (nanoMOFs) have been widely investigated because of their potential biocompatibility, high drug loadings, and progressive release. To enhance their properties, MOFs have been combined with magnetic nanoparticles (MNPs) to form magnetic nanocomposites (MNP@MOF) with additional functionalities. Due to the magnetic properties of the MNPs, their presence in the nanosystems enables potential combinatorial magnetic targeted therapy and diagnosis. In this Review, we analyze the four main synthetic strategies currently employed for the fabrication of MNP@MOF nanocomposites, namely, mixing, in situ formation of MNPs in presynthesized MOF, in situ formation of MOFs in the presence of MNPs, and layer-by-layer methods. Additionally, we discuss the current progress in bioapplications, focusing on drug delivery systems (DDSs), magnetic resonance imaging (MRI), magnetic hyperthermia (MHT), and theragnostic systems. Overall, we provide a comprehensive overview of the recent advances in the development and bioapplications of MNP@MOF nanocomposites, highlighting their potential for future biomedical applications with a critical analysis of the challenges and limitations of these nanocomposites in terms of their synthesis, characterization, biocompatibility, and applicability.

Magnetite Metal-Organic Frameworks: Applications in Environmental Remediation of Heavy Metals, Organic Contaminants, and Other Pollutants

Due to the increasing environmental pollution caused by human activities, environmental remediation has become an important subject for humans and environmental safety. The quest for beneficial pathways to remove organic and inorganic contaminants has been the theme of considerable investigations in the past decade. The easy and quick separation made magnetic solid-phase extraction (MSPE) a popular method for the removal of different pollutants from the environment. Metal-organic frameworks (MOFs) are a class of porous materials best known for their ultrahigh porosity. Moreover, these materials can be easily modified with useful ligands and form various composites with varying characteristics, thus rendering them an ideal candidate as adsorbing agents for MSPE. Herein, research on MSPE, encompassing MOFs as sorbents and Fe₃O₄ as a magnetic component, is surveyed for environmental applications. Initially, assorted pollutants and their threats to human and environmental safety are introduced with a brief introduction to MOFs and MSPE. Subsequently, the deployment of magnetic MOFs (MMOFs) as sorbents for the removal of various organic and inorganic pollutants from the environment is deliberated, encompassing the outlooks and perspectives of this field.

Adsorption and removal of organophosphorus pesticides from Chinese cabbages and green onions by using metal organic frameworks based on the mussel-inspired adhesive interface

Based on the mussel-inspired adhesive interface (Fe₃O₄-g-C₃N₄@PDA), a novel bionic metal-organic framework (Fe₃O₄-g-C₃N₄-PDA@MIL-101) was successfully prepared. The composite featured a high specific surface area and a multi-microchannel structure, as well as strong thermochemical stability. The structural property of Fe₃O₄-g-C₃N₄-PDA@MIL-101(Fe) was characterized, and the results indicated that Fe₃O₄, PDA, and MIL-101(Fe) were uniformly coated on the g-C₃N₄ surface. The adsorption and desorption of organophosphorus pesticides with Fe₃O₄-g-C₃N₄-PDA@MIL-101(Fe) were evaluated by batch experiments. This composite showed high adsorption efficiency and selective removal of coralox, phosalone, and chlorpyrifos. Under the optimal conditions, three organophosphorus pesticides were adsorbed from Chinese cabbage and green onion samples with Fe₃O₄-g-C₃N₄-PDA@MIL-101(Fe). The analytical method exhibited high sensitivity (LOD, 0.19-2.34 μg/L; LOQ, 0.65-7.82 μg/L), excellent practicality, and good stability, suggesting that Fe₃O₄-g-C₃N₄-PDA@MIL-101 was an ideal candidate magnetic adsorbent for the removal of organophosphorus pesticides in Chinese cabbage and green onion samples.

Amino functionalized magnetic covalent organic framework for magnetic solid-phase extraction of sulfonylurea herbicides in environmental samples from tobacco land

An amino-functionalized magnetic covalent organic framework composite TpBD-(NH2 )2 @Fe3 O4 (Tp=Tp1,3,5-triformylphloroglucinol, BD-(NH2 )2 is 3,3',4,4'-biphenyltetramine) was prepared by post-synthesis modification. Due to its abundant benzene rings and amino groups, large specific surface area and porous structure, the prepared TpBD-(NH2 )2 @Fe3 O4 exhibits high extraction efficiency toward sulfonylurea herbicides. Based on this, a new method of magnetic solid-phase extraction with TpBD-(NH2 )2 @Fe3 O4 as the sorbent combined with high-performance liquid chromatography and ultraviolet detection was developed for trace analysis of sulfonylurea herbicides in environmental water, soil and tobacco leaves samples from tobacco land. Under the optimized conditions, the limits of detection within 0.05-0.14 μg/L were achieved with a high enrichment factor of 217-260-fold, and the relative standard deviations were 4.9-7.5% (n = 7, c = 0.5 μg/L). The linear range was around three orders of magnitude with the square of correlation coefficient higher than 0.9936. The method was applied to analyze five sulfonylurea herbicides in the environmental water, soil, and tobacco leave samples collected from tobacco land. No sulfonylurea herbicides were detected in these samples. The recoveries of target sulfonylurea herbicides in spiked environmental water, soil, and tobacco leaf samples were found in the range of 90.7-104, 70.7-99.0, and 59.3-97.8%, respectively. The results illustrate that the established TpBD-(NH2 )2 @Fe3 O4 -magnetic solid-phase extraction- high-performance liquid chromatography-ultraviolet detection method is efficient for the analysis of trace sulfonylurea herbicides in environmental samples.

Preparation of magnetic metal-organic framework MIL-101(Fe) and its application in the extraction of anthraquinones in rhubarb

In this work, a magnetic octahedral metal organic framework (Fe₃ O₄ @NH₂ -MIL-101(Fe)) was synthesized for the magnetic solid phase extraction of three anthraquinones, including aloe-emodin, emodin, and physcion, in rhubarb. The Fe₃ O₄ @NH₂ -MIL-101(Fe) exhibited a high specific surface area of 259.2 m² /g with an average pore size of 6.0 nm and a high magnetic responsivity of 23.4 emu/g, which may be used as an adsorbent for rapid preconcentration and separation of target analytes. The main parameters for magnetic solid phase extraction of anthraquinones, including the amount of adsorbent, extraction time, extraction temperature, extraction pH, elution solvent, and elution time, were systematically optimized. The whole extraction process required a very low amount of adsorbent and a small volume of the sample. Besides, under the optimized conditions, the method showed satisfactory spiked recovery for anthraquinones in the range of 93.3%-109.1%, and the LODs were 1.7-3.4 ng/mL. The RSDs for intra- and inter- day precision were 0.2%-1.3% and 0.2%-0.6%, respectively. The experimental results indicate that the developed method is feasible for the analysis of anthraquinones in rhubarb. This article is protected by copyright. All rights reserved.

Metal-Organic Frameworks in Agriculture

Agrochemicals, which are crucial to meet the world food qualitative and quantitative demand, are compounds used to kill pests (insects, fungi, rodents, or unwanted plants). Regrettably, there are some important issues associated with their widespread and extensive use (e.g., contamination, bioaccumulation, and development of pest resistance); thus, a reduced and more controlled use of agrochemicals and thorough detection in food, water, soil, and fields are necessary. In this regard, the development of new functional materials for the efficient application, detection, and removal of agrochemicals is a priority. Metal-organic frameworks (MOFs) with exceptional sorptive, recognition capabilities, and catalytical properties have very recently shown their potential in agriculture. This Review emphasizes the recent advances in the use of MOFs in agriculture through three main views: environmental remediation, controlled agrochemical release, and detection of agrochemicals.

Anti-Influenza Virus Study of Composite Material with MIL-101(Fe)-Adsorbed Favipiravir

Nanomaterial technology has attracted much attention because of its antibacterial and drug delivery properties, among other applications. Metal-organic frameworks (MOFs) have advantages, such as their pore structure, large specific surface area, open metal sites, and chemical stability, over other nanomaterials, enabling better drug encapsulation and adsorption. In two examples, we used the common pathogenic bacterium Staphylococcus aureus and highly infectious influenza A virus. A novel complex MIL-101(Fe)-T705 was formed by synthesizing MOF material MIL-101(Fe) with the drug favipiravir (T-705), and a hot solvent synthesis method was applied to investigate the in vitro antibacterial and antiviral activities. The results showed that MIL-101(Fe)-T705 combined the advantages of nanomaterials and drugs and could inhibit the growth of Staphylococcus aureus at a concentration of 0.0032 g/mL. Regarding the inhibition of influenza A virus, MIL-101(Fe)-T705 showed good biosafety at 12, 24, 48, and 72 h in addition to a good antiviral effect at concentrations of 0.1, 0.2, 0.4, 0.8, 1.6, and 3 μg/mL, which were higher than MIL-101(Fe) and T-705.

Efficiency and mechanism of C18-functionalized magnetic nanoparticles for extracting weakly polar pesticides from human serum determined by UHPLC-QTOF-MS and molecular dynamics simulations

Detecting pesticide residues in human serum is a challenging process due to trace-level chronic exposure. Several methods using magnetic adsorbents have been developed for analyzing pesticide residue levels in human serum, but it is still difficult to achieve lower quantitative levels, and the adsorption mechanism for extracting pesticides is unclear. Herein, we propose a feasibility concept of using C₁₈-functionalized magnetic nanoparticles for the adsorption of target pesticides, focusing on the extensively used weakly polar pesticides based on molecular dynamics (MD) simulations. To support this, the facilitated target nanoparticles of Fe₃O₄@SiO₂-C₁₈ were synthesized at a size of 12-13 nm with a magnetic saturation of 40 emu/g. After optimizing and establishing the extraction conditions (1.8 mL C₁₈ modifier, 10 mg sorbents, 3 min adsorption time, 1000 μL ACN for desorption eluent at pH 3.8 and 5 min desorption time), which exhibited recovery = 72.3%-118.3% with RSDs = 0.03-6.57, linearity at 0.01-10 ng/mL with R² = 0.9561-0.9993, and LODs = 0.01-0.30 ng/mL for the 11 weakly polar pesticides in human serum. Furthermore, the mechanism by which the C₁₈ group selectively extracts weakly polar pesticides was confirmed by binding van der Waals and electrostatic interactions under stable and strong binding energy. The extraction process of efficient adsorption and desorption with C₁₈ functional magnetite nanoparticles suggests a simple method for detecting weakly polar pesticides. The concept may lead to a general approach to analyzing multiple pesticide residues in human serum at trace levels.

Adsorptive removal of dyes from wastewater using a metal-organic framework: A review

Water pollution from synthetic dyes is a growing environmental concern because many dyes have carcinogenic effects on humans and aquatic life. Adsorption is a widely used technology for the separation and removal of dyes from wastewater. However, the dye removal process using conventional adsorbents is not sufficiently efficient for industrial wastewater. Metal-organic frameworks (MOFs) addresses these drawbacks. MOF showed excellent dye removal and degradation capacity owing to its multifunctionality, water-stability, large surface area, tunable pore size and recyclability. Magnetic MOFs retained excellent performance up to several consecutive cycles. Modified MOFs performed as Fenton-like catalysis process which generated abundant reactive radicals that degraded complex organic dyes into simple and less toxic forms which were further adsorbed onto the MOF. This review systematically compiles in-depth studies on the adsorptive removal of dyes from wastewater, MOF adsorption mechanisms, major influencing factors, to adsorption efficiency of MOFs. While all MOFs adsorb dyes through electrostatic attraction, the type of MOF, presence of functional groups, ligands, and pH significantly control the adsorption mechanism. Before developing an MOF, optimization and upgradation of factors and interaction between available adsorption site and adsorbate is needed. Finally, the prospects and new frontiers of MOFs in sustainable water treatment is discussed.

On the use of metal-organic frameworks for the extraction of organic compounds from environmental samples

The determination of trace metals and organic contaminants in environmental samples, such as water, air, soil, and sediment, is until today a challenging process for the analytical chemistry. Metal-organic frameworks (MOFs) are novel porous nanomaterials that are composed of metal ions and an organic connector. These materials are gaining more and more attention due to their superior characteristics, such as high surface area, tunable pore size, mechanical and thermal stability, luminosity, and charge transfer ability between metals and ligands. Among the various applications of MOFs are gas storage, separation, catalysis, and drug delivery. Recently, MOFs have been successfully introduced in the field of sample preparation for analytical chemistry and they have been used for sample pretreatment of various matrices. This review focuses on the applications of MOFs as novel adsorbents for the extraction of organic compounds from environmental samples.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine.

Extraction and electrochemical sensing of pesticides in food and environmental samples by use of polydopamine-based materials

Polydopamine has high adsorption capacities for pollutants such as pesticides in food and environmental matrices. Consequently, it has found applications in some sorbent-based micro-extraction techniques such as solid phase micro-extraction and magnetic solid phase extraction. This paper gives a detailed review of the application of polydopamine-based adsorbents for the extraction of pesticides in food and environmental matrices using these techniques. The adhesive properties of polydopamine have made it to be a suitable material for the immobilisation of the components of electrochemical sensors used to detect pesticides in food and environmental matrices. This paper also gives a comprehensive review on the application of polydopamine in electrochemical sensors such as acetylcholinesterase sensors, molecularly imprinted sensors and aptasensors. The use of polydopamine-based adsorbents during the extraction and electrochemical sensing of pesticides in food and environmental matrices is not free of challenges. In this review, the challenges encountered during the use of polydopamine-based adsorbents are also discussed.

Photocatalytic Degradation of Tetracycline by a Novel (CMC)/MIL-101(Fe)/β-CDP Composite Hydrogel

Herein, we report a novel carboxymethyl cellulose (CMC)/MIL-101 (Fe)/poly(β-cyclodextrin) (β-CDP) hydrogel with high photocatalytic activity. β-CDP can significantly enhance the photoactivity of MIL-101(Fe) in the hydrogel prepared by a simple solvothermal method. The structure and property of this composite hydrogel were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Tetracycline was selected as a model pharmaceutical antibiotic to evaluate the photocatalytic activity of the composite hydrogel under visible light irradiation and darkness, respectively. This composite hydrogel shows excellent activity for degrading pharmaceutical antibiotics under visible light irradiation. The increased photocatalytic activity can be attributed to β-CDP, which acts as a promoter and affords an efficient separation of photogenerated electron-hole pairs of MIL-101(Fe). Moreover, the composite hydrogel is shown to have good water retainability. The hydrogel is inexpensive and shows high photocatalytic activity. Hence, it can be used as an efficient photocatalytic material.

Greenness of magnetic nanomaterials in miniaturized extraction techniques: A review

Green analytical chemistry principles should be followed, as much as possible, and particularly during the development of analytical sample preparation methods. In the past few years, outstanding materials such as ionic liquids, metal-organic frameworks, carbonaceous materials, molecularly imprinted materials, and many others, have been introduced in a wide variety of miniaturized techniques in order to reduce the amount of solvents and sorbents required during the analytical sample preparation step while pursuing more efficient extraction methods. Among them, magnetic nanomaterials (MNMs) have gained special attention due to their versatile properties. Mainly, their ability to be separated from the sample matrix using an external magnetic field (thus enormously simplifying the entire process) and their easy combination with other materials, which implies the inclusion of a countless number of different functionalities, highly specific in some cases. Therefore, MNMs can be used as sorbents or as magnetic support for other materials which do not have magnetic properties, the latter permiting their combination with novel materials. The greenness of these magnetic sorbents in miniaturized extractions techniques is generally demonstrated in terms of their ease of separation and amount of sorbent required, while the nature of the material itself is left unnoticed. However, the synthesis of MNMs is not always as green as their applications, and the resulting MNMs are not always as safe as desired. Is the analytical sample preparation field ready for using green magnetic nanomaterials? This review offers an overview, from a green analytical chemistry perspective, of the current state of the use of MNMs as sorbents in microextraction strategies, their preparation, and the analytical performance offered, together with a critical discussion on where efforts should go.

Metal-organic framework for the extraction and detection of pesticides from food commodities

Pesticide residues in food matrices, threatening the survival and development of humanity, is one of the critical challenges worldwide. Metal-organic frameworks (MOFs) possess excellent properties, which include excellent adsorption capacity, tailorable shape and size, hierarchical structure, numerous surface-active sites, high specific surface areas, high chemical stabilities, and ease of modification and functionalization. These promising properties render MOFs as advantageous porous materials for the extraction and detection of pesticides in food samples. This review is based on a brief introduction of MOFs and highlights recent advances in pesticide extraction and detection through MOFs. Furthermore, the challenges and prospects in this field are also described.

Introducing reticular chemistry into agrochemistry

For survival and quality of life, human society has sought more productive, precise, and sustainable agriculture. Agrochemistry, which solves farming issues in a chemical manner, is the core engine that drives the evolution of modern agriculture. To date, agrochemistry has utilized chemical technologies in the form of pesticides, fertilizers, veterinary drugs and various functional materials to meet fundamental demands from human society, while increasing the socio-ecological consequences due to inefficient use. Thus, more useful, precise, and designable scaffolding materials are required to support sustainable agrochemistry. Reticular chemistry, which weaves molecular units into frameworks, has been applied in many fields based on two cutting-edge porous framework materials, namely metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs). With flexibility in composition, structure, and pore chemistry, MOFs and COFs have shown increasing functionalities associated with agrochemistry in the last decade, potentially introducing reticular chemistry as a highly accessible chemical toolbox into agrochemical technologies. In this critical review, we will demonstrate how reticular chemistry shapes the future of agrochemistry in the fields of farm sensing, agro-ecological preservation and reutilization, agrochemical formulations, smart indoor farming, agrobiotechnology, and beyond.

Metal-Organic Frameworks in Green Analytical Chemistry

Metal-organic frameworks (MOFs) are porous hybrid materials composed of metal ions and organic linkers, characterized by their crystallinity and by the highest known surface areas. MOFs structures present accessible cages, tunnels and modifiable pores, together with adequate mechanical and thermal stability. Their outstanding properties have led to their recognition as revolutionary materials in recent years. Analytical chemistry has also benefited from the potential of MOF applications. MOFs succeed as sorbent materials in extraction and microextraction procedures, as sensors, and as stationary or pseudo-stationary phases in chromatographic systems. To date, around 100 different MOFs form part of those analytical applications. This review intends to give an overview on the use of MOFs in analytical chemistry in recent years (2017–2019) within the framework of green analytical chemistry requirements, with a particular emphasis on possible toxicity issues of neat MOFs and trends to ensure green approaches in their preparation.

Ag/AgCl/MIL-101(Fe) Catalyzed Degradation of Methylene Blue under Visible Light Irradation

A novel photo-Fenton catalyst named Ag/AgCl/MIL-101(Fe) was synthesized by the method of precipitation and photo reduction and characterized by X-ray diffraction patterns (XRD), Brunauer-Emmett-Teller (BET) measurements, Fourier transform infrared spectra (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra. Moreover, the catalytic activity of the synthesized catalyst was tested using methylene blue (MB) as the target pollutant. The obtained results illustrated that the plasmonic material Ag/AgCl was successfully loaded on MIL-101(Fe) and the obtained catalyst exhibited an excellent catalytic activity under visible light at the neutral pH. According to the analyses of Plackett-Burman and Box-Behnken design, the optimum conditions for MB degradation were obtained. Under these conditions, the MB decolorization and mineralization efficiencies could reach to 99.75% and 65.43%, respectively. The recycling experiments also showed that the as-prepared catalyst displayed good reusability. In addition, the possible reaction mechanisms for the heterogeneous photo-Fenton system catalyzed by Ag/AgCl/MIL-101(Fe) were derived. The synthesized catalyst provides a promising approach to degrade organic pollutants in waste water.