Application of metal and metal oxide nanoparticles@MOFs

Exosomes encapsulated in hydrogels for effective central nervous system drug delivery

The targeted delivery of pharmacologically active molecules, metabolites, and growth factors to the brain parenchyma has become one of the major challenges following the onset of neurodegeneration and pathological conditions. The therapeutic effect of active biomolecules is significantly impaired after systemic administration in the central nervous system (CNS) because of the blood-brain barrier (BBB). Therefore, the development of novel therapeutic approaches capable of overcoming these limitations is under discussion. Exosomes (Exo) are nano-sized vesicles of endosomal origin that have a high distribution rate in biofluids. Recent advances have introduced Exo as naturally suitable bio-shuttles for the delivery of neurotrophic factors to the brain parenchyma. In recent years, many researchers have attempted to regulate the delivery of Exo to target sites while reducing their removal from circulation. The encapsulation of Exo in natural and synthetic hydrogels offers a valuable strategy to address the limitations of Exo, maintaining their integrity and controlling their release at a desired site. Herein, we highlight the current and novel approaches related to the application of hydrogels for the encapsulation of Exo in the field of CNS tissue engineering.

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.

Exploring the Role of Ligand Connectivity in MOFs Mechanical Stability: The Case of MIL-100(Cr)

The key parameters governing the mechanical stability of highly porous materials such as metal-organic frameworks (MOFs) are yet to be clearly understood. This study focuses on the role of the linker connectivity by investigating the mechanical stability of MIL-100(Cr), a mesoporous MOF with a hierarchical structure and a tritopic linker, and comparing it to MIL-101(Cr) having instead a ditopic linker. Using synchrotron X-ray diffraction and infrared spectroscopy, we investigate the high-pressure behavior of MIL-100(Cr) with both solid and fluid pressure transmitting media (PTM). In the case of a solid medium, MIL-100(Cr) undergoes amorphization at about 0.6 GPa, while silicone oil as a PTM delays amorphization until 12 GPa due to the fluid penetration into the pores. Both of these values are considerably higher than those of MIL-101(Cr). MIL-100(Cr) also exhibits a bulk modulus almost ten times larger than that of MIL-101(Cr). This set of results coherently proves the superior stability of MIL-100(Cr) under compression. We ascribe this to the higher connectivity of the organic linker in MIL-100(Cr), which enhances its interconnection between the metal nodes. These findings shed light on the importance of linker connectivity in the mechanical stability of MOFs, a relevant contribution to the quest for designing more robust MOFs.

Drug Delivery Angle for Various Atherosclerosis and Aneurysm Percentages of the Carotid Artery

Stroke is the second cause of mortality among adult males and the first cause of death in adult females all around the world. It is also recognized as one of the most important causes of morbidity and dementia in adults. Stenosis or rupture of the only channels of the blood supply from the heart to the brain (carotid arteries) is among the main causes of stroke. In this regard, treatment of the lesions of carotid arteries, including atherosclerosis and aneurysm, could be a huge step in preventing stroke and improving brain performance. Targeted drug delivery by drug-carrying nanoparticles is the latest method for optimal delivery of drug to the damaged parts of the artery. In this study, a wide range of carotid artery lesions, including different percentages of atherosclerosis and aneurysm, were considered. After analyzing the dynamics of the fluid flow in different damaged regions and selecting the magnetic framework with proper ligand (Fe3O4@MOF) as the drug carrier, the size of the particles and their number per cycle were analyzed. Based on the results, the particle size of 100 nm and the use of 300 particles per injection at each cardiac cycle can result in maximum drug delivery to the target site. Then, the effect of the hospital bed angle on drug delivery was investigated. The results showed a unique optimal drug delivery angle for each extent of atherosclerosis or aneurysm. For example, in a 50% aneurysm, drug delivery at an angle of 30° is about 387% higher than that at an angle of 15°. Finally, simulation of real geometry indicated the effectiveness of simple geometry instead of real geometry for the simulation of carotid arteries, which can remarkably decrease the computational time and costs.

Metal-Organic Framework as a New Type of Magnetothermally-Triggered On-Demand Release Carrier

The development of external stimuli-controlled payload systems has been sought after with increasing interest toward magnetothermally-triggered drug release (MTDR) carriers due to their non-invasive features. However, current MTDR carriers present several limitations, such as poor heating efficiency caused by the aggregation of iron oxide nanoparticles (IONPs) or the presence of antiferromagnetic phases which affect their efficiency. Herein, a novel MTDR carrier is developed using a controlled encapsulation method that fully fixes and confines IONPs of various sizes within the metal-organic frameworks (MOFs). This novel carrier preserves the MOF's morphology, porosity, and IONP segregation, while enhances heating efficiency through the oxidation of antiferromagnetic phases in IONPs during encapsulation. It also features a magnetothermally-responsive nanobrush that is stimulated by an alternating magnetic field to enable on-demand drug release. The novel carrier shows improved heating, which has potential applications as contrast agents and for combined chemo and magnetic hyperthermia therapy. It holds a great promise for magneto-thermally modulated drug dosing at tumor sites, making it an exciting avenue for cancer treatment.

CO2 conversion in a dielectric barrier discharge plasma by argon dilution over MgO/HKUST-1 catalyst using response surface methodology

Metal-organic frameworks (MOFs) as carbon dioxide adsorption in combination with metal oxides have shown catalyst application in CO2 conversion. Herein, the MgO/HKUST-1 catalyst is synthesized to direct conversion of CO2 upon dilution by argon in a cylindrical dielectric barrier discharge (DBD) reactor. A water-cooling circulation adjusts the reactor temperature, and aluminum powder is used as a high-voltage electrode. The effect of the discharge power, feed flow rate, CO2 fraction, and their interaction in plasma and plasma catalyst method on CO2 conversion (R1), effective CO2 conversion (R2), and energy efficiency (R3) is evaluated by central composite design (CCD) based on response surface methodology. The Analysis of Variance (ANOVA) results demonstrate that the quadratic regression model describes CO2 conversion and effective CO2 conversion, and the reduced cubic model describes energy efficiency. The results indicate that the method (plasma, plasma catalyst) and discharge power on R1 and R2 have a considerable effect. Also, the method and CO2 fraction on R3 have the greatest impact, respectively. In the plasma and plasma catalyst method maximum CO2 conversion is 12.3% and 20.5% at a feed flow rate of 80 ml/min, CO2 fraction of 50%, and discharge power of 74 W.

Reproductive and whole-body toxicity of Ag-doped and -undoped ZIF-8 nanoparticles and the building blocks: An Artemia-based comparative bioassay

The present research assessed, for the first time, toxicity of ZIF-8 (1 mg/L) and the building blocks (0.1 mg/L Zn2+ and 0.4 mg/L 2-methylimidazole (2-MIm)), besides that of AgNPs@ZIF-8 (0.25, 0.5, and 1 mg/L) and AgNO3 (0.1 mg/L) to aquatic organisms. Two consecutive generations (F0 & F1) of Artemia salina were exposed to these chemicals. All of the chemical treatments considerably caused mortality in F0, especially AgNPs@ZIF-8 and AgNO3, whereas F1 displayed notable tolerance and survived comparable to the control group, except in the case of AgNO3 treatment. Similarly, growth indices (weight, mainly in ZIF-8, Zn2+, and 2-MIm; length, in Ag-doped ZIF-8 and AgNO3) were significantly retarded in F0 and especially F1 of all treatments, and 2-MIm caused the greatest length retardation in F0. AgNPs@ZIF-8 (0.5 and 1 mg/L), 2-MIm, and AgNO3 postponed the ovary emergence in about 40%-60% of the exposed F0, and ZIF-8 delayed this phenomenon in some individuals of F0 and F1 up to 6 days. This temporal disturbance was also observed in time to first brood of almost all experimental F0 and F1 groups, with being over 80% of F1 exposed to ZIF-8, 2-MIm, and Zn2+, as well as about 50% of F0 treated with 2-MIm, and Zn2+. The highest neonate number was recorded for F0 and F1 exposed to AgNO3 and Zn2+, while ZIF-8 and, importantly, 2-MIm decreased the reproductivity to the lowest levels in both generations. Generally, the reproductive frequency was significantly decreased in all F0 and F1 treatments, especially 2-MIm, ZIF-8, AgNPs@ZIF-8 (0.25 & 1 mg/L). This study highlighted the neglected importance of 2-MIm in assessing overall toxicity of ZIF-8, and even other organic ligands of MOFs, and also filled a gap in the literature by investigating the potential effect of additives such as AgNPs on the toxicity of ZIF-8 and other MOFs.

Advances in metal-organic frameworks for water remediation applications

Rapid industrialization and agricultural development have resulted in the accumulation of a variety of harmful contaminants in water resources. Thus, various approaches such as adsorption, photocatalytic degradation and methods for sensing water contaminants have been developed to solve the problem of water pollution. Metal-organic frameworks (MOFs) are a class of coordination networks comprising organic-inorganic hybrid porous materials having organic ligands attached to inorganic metal ions/clusters via coordination bonds. MOFs represent an emerging class of materials for application in water remediation owing to their versatile structural and chemical characteristics, such as well-ordered porous structures, large specific surface area, structural diversity, and tunable sites. The present review is focused on recent advances in various MOFs for application in water remediation via the adsorption and photocatalytic degradation of water contaminants. The sensing of water pollutants using MOFs via different approaches, such as luminescence, electrochemical, colorimetric, and surface-enhanced Raman spectroscopic techniques, is also discussed. The high porosity and chemical tunability of MOFs are the main driving forces for their widespread applications, which have huge potential for their commercial use.

Highly Luminescent Eu3+-Incorporated Zr-MOFs as Fluorescence Sensors for Detection of Hazardous Organic Compounds in Water and Fruit Samples

Considering the risk of toxic organic compounds to both human health and the environment, highly luminescent Eu3+-incorporated amino-functionalized zirconium metal-organic frameworks, namely, Eu/MOF and Eu@MOF were synthesized via the solvothermal method. The synthesized luminescent europium-incorporated MOFs act as outstanding sensor materials for diphenylamine and dinitrobenzene detection in water and fruit samples. The synergistic effect of Eu3+ metal ions and amino-functionalized MOFs enhances the luminescent properties of the MOFs improving the fluorescence sensing ability toward the analytes. The enhancement in the detection capacity of the Eu3+-incorporated sensors than the sole MOF toward toxic organic compounds was confirmed using the Stern-Volmer equation of limit of detection (LOD) measurements along with fluorescence lifetime measurements. The sensors exhibited turn-on fluorometric detection toward their respective analytes due to the inner filter effect. The plausible fluorescence sensing mechanism has been studied. The DFT calculations have been integrated to study the structure, stability, and charge transfer processes.

Multifunctional, Hybrid Materials Design via Spray-Drying: Much more than Just Drying

Spray-drying is a popular and well-known "drying tool" for engineers. This perspective highlights that, beyond this application, spray-drying is a very interesting and powerful tool for materials chemists to enable the design of multifunctional and hybrid materials. Upon spray-drying, the confined space of a liquid droplet is narrowed down, and its ingredients are forced together upon "falling dry." As  detailed in this article, this enables the following material formation strategies either individually or even in combination: nanoparticles and/or molecules can be assembled; precipitation reactions as well as chemical syntheses can be performed; and templated materials can be designed. Beyond this, fragile moieties can be processed, or "precursor materials" be prepared. Post-treatment of spray-dried objects eventually enables the next level in the design of complex materials. Using spray-drying to design (particulate) materials comes with many advantages-but also with many challenges-all of which are outlined here. It is believed that multifunctional, hybrid materials, made via spray-drying, enable very unique property combinations that are particularly highly promising in myriad applications-of which catalysis, diagnostics, purification, storage, and information are highlighted.

Enhancing stability via confining Rh-P species in ZIF-8 for hydroformylation of 1-octene

The stability of Rh-based heterogeneous catalysts is a key issue in the hydroformylation of olefins. Confinement of active Rh species has been considered an effective strategy to achieve stable catalysts. In this work, a phosphine ligand was successfully confined in ZIF-8 material and coordinated with Rh metal by a reduction procedure to develop an efficient and stable Rh-based catalyst for hydroformylation of 1-octene. The results indicate that the catalyst reduced at 300 °C under H2 atmosphere exhibits better stability than that with NaBH4 as reductant and undoped P catalyst. Various characterization studies demonstrate that the superior performance is due to the strong interaction between Rh metal and P, which inhibits the leaching of active Rh species. This work reveals an effective strategy for the synthesis of highly stable catalysts for use in the hydroformylation reaction.

Recent Advances in Multifunctional Reticular Framework Nanoparticles: A Paradigm Shift in Materials Science Road to a Structured Future

Porous organic frameworks (POFs) have become a highly sought-after research domain that offers a promising avenue for developing cutting-edge nanostructured materials, both in their pristine state and when subjected to various chemical and structural modifications. Metal-organic frameworks, covalent organic frameworks, and hydrogen-bonded organic frameworks are examples of these emerging materials that have gained significant attention due to their unique properties, such as high crystallinity, intrinsic porosity, unique structural regularity, diverse functionality, design flexibility, and outstanding stability. This review provides an overview of the state-of-the-art research on base-stable POFs, emphasizing the distinct pros and cons of reticular framework nanoparticles compared to other types of nanocluster materials. Thereafter, the review highlights the unique opportunity to produce multifunctional tailoring nanoparticles to meet specific application requirements. It is recommended that this potential for creating customized nanoparticles should be the driving force behind future synthesis efforts to tap the full potential of this multifaceted material category.

Recent advances in catalytic synthesis of 2,5-furandimethanol from 5-hydroxymethylfurfural and carbohydrates

5-Hydroxymethylfurfural (HMF) is a versatile platform chemical derived from the dehydration of renewable carbohydrates (typically glucose/fructose-based monosaccharides, oligosaccharides, and polysaccharides). Some useful compounds, such as 2,5-furandimethanol (FDM), 2,5-dimethylfuran (DMF) and 2,5-dimethyltetrahydrofuran (DMTHF), have been synthesized by reduction of HMF. Among these, FDM is a promising diol and can be further converted towards fine chemicals, liquid fuels and polymer materials. In this review, some typical catalytic systems for the synthesis of FDM from both HMF and carbohydrates were summarized. The discussion focused on controlling the reaction networks for the reduction of HMF. The reaction mechanisms and the stability of the catalysts were introduced briefly. Last but not least, the prospects of effective production of FDM were discussed as well.

Bionanomining of copper-based nanoparticles using pre-processed mine tailings as the precursor

The bacterial synthesis of copper nanoparticles emerges as an eco-friendly alternative to conventional techniques since it comprises a single-step and bottom-up approach, which leads to stable metal nanoparticles. In this paper, we studied the biosynthesis of Cu-based nanoparticles by Rhodococcus erythropolis ATCC4277 using a pre-processed mining tailing as a precursor. The influence of pulp density and stirring rate on particle size was evaluated using a factor-at-time experimental design. The experiments were carried out in a stirred tank bioreactor for 24 h at 25 °C, wherein 5% (v/v) of bacterial inoculum was employed. The O₂ flow rate was maintained at 1.0 L min^-1 and the pH at 7.0. Copper nanoparticles (CuNPs), with an average hydrodynamic diameter of 21 ± 1 nm, were synthesized using 25 g.L^-1 of mining tailing and a stirring rate of 250 rpm. Aiming to visualize some possible biomedical applications of the as-synthesized CuNPs, their antibacterial activity was evaluated against Escherichia coli and their cytotoxicity was evaluated against Murine Embryonic Fibroblast (MEF) cells. The 7-day extract of CuNPs at 0.1 mg mL^-1 resulted in 75% of MEF cell viability. In the direct method, the suspension of CuNPs at 0.1 mg mL^-1 resulted in 70% of MEF cell viability. Moreover, the CuNPs at 0.1 mg mL^-1 inhibited 60% of E. coli growth. Furthermore, the NPs were evaluated regarding their photocatalytic activity by monitoring the oxidation of methylene blue (MB) dye. The CuNPs synthesized showed rapid oxidation of MB dye, with the degradation of approximately 65% of dye content in 4 h. These results show that the biosynthesis of CuNPs by R. erythropolis using pre-processed mine tailing can be a suitable method to obtain CuNPs from environmental and economical perspectives, resulting in NPs useful for biomedical and photocatalytic applications.

High Proton Conductivity of the UiO-66-NH2-SPES Composite Membrane Prepared by Covalent Cross-Linking

A sulfonated poly(ethersulfone) (SPES)-metal-organic framework (MOF) film with excellent proton conductivity was synthesized by anchoring UiO-66-NH₂ to the main chain of the aromatic polymer through the Hinsberg reaction. The chemical bond was formed between the amino group in MOFs and the -SO₂Cl group in chlorosulfonated poly(ethersulfones) to conduct protons in the proton channel of the membrane, making the membrane have excellent proton conductivity. UiO-66-NH₂ is successfully prepared as a result of the consistency of the experimental and simulated powder X-ray diffraction (PXRD) patterns of MOFs. The existence of absorption peaks of characteristic functional groups in Fourier transform infrared (FTIR) spectra proved the successful preparation of SPES, PES-SO₂Cl, and a composite film. The results of the AC impedance test indicate that the composite film with a 3% mass fraction has the best proton conductivity of 0.215 S·cm^-1, which is 6.2 times higher than that of the blended film without a chemical bond at 98% RH and 353 K. To our knowledge, there are rarely any reports on the preparation of a composite membrane by directly linking MOFs and the membrane matrix with chemical bonds. This work provides a good way to synthesize the highly conductive proton exchange film.

Green synthesis of highly efficient and stable copper oxide nanoparticles using an aqueous seed extract of Moringa stenopetala for sunlight-assisted catalytic degradation of Congo red and alizarin red s

Environmental pollution by organic pollutants because of population growth and industrial expansion is a global concern. Following this, the fabrication of single and efficient nanomaterials for pollution control is highly demanded. Under this study, highly efficient and stable copper oxide nanoparticles (CuO NPs) were synthesized through the green method using Moringa stenopetala seed extract. XRD, UV-vis, FT-IR, and SEM were applied to characterize the synthesized material. From XRD data, the average particle size was found to be 6.556 nm, and the nanoparticles are crystalline in nature. The formation of CuO NPs was demonstrated by FT-IR spectra of Cu-O in different bending vibration bands at 535 cm-1 and 1122 cm-1, as well as stretching vibration of Cu-O at 1640 cm-1. From UV-visible spectroscopic measurements, the energy band gap of greenly synthesized CuO NPs was found to be 1.73 eV. The SEM result shows that the nanoparticles' surfaces are rough, with some of the particles having spherically random orientation. The photodegradation efficiency of green synthesized CuO NPs photocatalyst was found to be 98.35% for Congo red at optimum experimental parameters (initial concentration, 25 mg/L; exposure time, 120 min; catalyst dose, 0.2 g; and pH, 5) and 95.4% for Alizarin Red S at optimum experimental parameters (catalyst dose, 0.25 g; initial concentration, 40 mg/L; exposure time, 120 min; and pH, 4.6). The COD values determined for the degraded product strongly support the complete mineralization of the dyes toward nontoxic materials. Reusability of the catalyst was investigated for five cycles, and the results clearly indicate the green synthesized CuO NPs are highly stable, can be used for several times, and are cost-effective as well. The degradation of Congo red and Alizarin red S on the surface of the CuO NPs follows the MBG kinetic model.

Progress and opportunities for metal-organic framework composites in electrochemical sensors

Metal-organic framework composites have the advantages of large surface area, high porosity, strong catalytic efficiency and good stability, which provide a great possibility of finding excellent electrode materials for electrochemical sensors. However, MOF composites still face various challenges and difficulties, which limit their development and application. This paper reviews the application of MOF composites in electrochemical sensors, including MOF/carbon composites, MOF/metal nanoparticle composites, MOF/metal oxide composites and MOF/enzyme composites. In addition, the application challenges of MOF composites in electrochemical sensors are summarized. Finally, the application prospect for MOF composites is considered to promote the synthesis of more MOF composites with excellent properties.

Organocatalysis with carbon nitrides

Carbon nitrides, a distinguished class of metal-free catalytic materials, have presented a good potential for chemical transformations and are expected to become prominent materials for organocatalysis. This is largely possible due to their low cost, exceptional thermal and chemical stability, non-toxicity, ease of functionalization, porosity development, etc. Especially, the carbon nitrides with increased porosity and nitrogen contents are more versatile than their bulk counterparts for catalysis. These N-rich carbon nitrides are discussed in the earlier parts of the review. Later, the review highlights the role of such carbon nitride materials for the various organic catalytic reactions including Knoevenagel condensation, oxidation, hydrogenation, esterification, transesterification, cycloaddition, and hydrolysis. The recently emerging concepts in carbon nitride-based organocatalysis have been given special attention. In each of the sections, the structure-property relationship of the materials was discussed and related to their catalysis action. Relevant comparisons with other catalytic materials are also discussed to realize their real potential value. The perspective, challenges, and future directions are also discussed. The overall objective of this review is to provide up-to-date information on new developments in carbon nitride-based organic catalysis reactions that could see them rising as prominent catalytic materials in the future.

Molecular docking with SARS-CoV-2 and potential drug property of a bioactive novel Zn(II) polymer: A combined experimental and theoretical study

A new Zn(II) coordination polymer based on o-phthalato (Phth) and 2-aminopyridine (2-Ampy) viz. {[Zn(2-Ampy)₂(Phth)]∙(H₂O)]}_n (1) has been synthesized at room temperature and characterized by elemental analyses, electronic spectroscopy, FT-IR spectroscopy, thermal analysis (TGA/DSC), powder X-ray diffraction (PXRD) and single crystal X-ray diffraction. The basic trimeric units of 1 form a polymeric chain by N-H⋯O and π⋯π interactions. These polymeric chains interconnect through various non-covalent interactions in two perpendicular directions to ultimately give rise to a 3D architecture of 1. The interesting non-covalent interactions in 1, contributing to its stability in the solid state are studied by Hirshfeld surface analysis and other different theoretical tools. Molecular docking study of 1 is performed against six different proteins of SARS-CoV-2. The drug potential of the synthesized compound is evaluated by ADMET calculations.

Metal-Organic Framework-Based Materials for Wastewater Treatment: Superior Adsorbent Materials for the Removal of Hazardous Pollutants

In previous years, different pollutants, for example, organic dyes, antibiotics, heavy metals, pharmaceuticals, and agricultural pollutants, have been of note to the water enterprise due to their insufficient reduction during standard water and wastewater processing methods. MOFs have been found to have potential toward wastewater management. This Review focused on the synthesis process (such as traditional, electrochemical, microwave, sonochemical, mechanochemical, and continuous-flow spray-drying method) of MOF materials. Moreover, the properties of the MOF materials have been discussed in detail. Further, MOF materials' applications for wastewater treatment (such as the removal of antibiotics, organic dyes, heavy metal ions, and agricultural waste) have been discussed. Additionally, we have compared the performances of some typical MOFs-based materials with those of other commonly used materials. Finally, the study's current challenges, future prospects, and outlook have been highlighted.

Polarization-dependent plasmonic heating in epitaxially grown multilayered metal-organic framework thin films embedded with Ag nanoparticles

The development of metal-organic framework (MOF) thin films with various functionalities has paved the way for research into a wide variety of applications. MOF-oriented thin films can exhibit anisotropic functionality in the not only out-of-plane but also in-plane directions, making it possible to utilize MOF thin films for more sophisticated applications. However, the functionality of oriented MOF thin films has not been fully exploited, and finding novel anisotropic functionality in oriented MOF thin films should be cultivated. In the present study, we report the first demonstration of polarization-dependent plasmonic heating in a MOF oriented film embedded with Ag nanoparticles (AgNPs), pioneering an anisotropic optical functionality in MOF thin films. Spherical AgNPs exhibit polarization-dependent plasmon-resonance absorption (anisotropic plasmon damping) when incorporated into an anisotropic lattice of MOFs. The anisotropic plasmon resonance results in a polarization-dependent plasmonic heating behavior; the highest elevated temperature was observed in case the polarization of incident light is parallel to the crystallographic axis of the host MOF lattice favorable for the larger plasmon resonance, resulting in polarization-controlled temperature regulation. Such spatially and polarization selective plasmonic heating offered by the use of oriented MOF thin films as a host can pave the way for applications such as efficient reactivation in MOF thin film sensors, partial catalytic reactions in MOF thin film devices, and soft microrobotics in composites with thermo-responsive materials.

Core-shell Au@MIL-100 (Fe) as an enhanced substrate for flunixin meglumine ultra-sensitive detection

This study aimed to develop and validate a simple and efficient surface-enhanced Raman spectroscopy (SERS) method to determine flunixin meglumine (FM) residues in animal tissues through using core-shell Au@MIL-100 (Fe) as enhanced substrate. Au@MIL-100 (Fe) composite material was synthesized by coating metal-organic framework materials (MOFs) on the surface of gold nanoparticles using the solvothermal method. Transmission electron microscopy (TEM), UV-vis spectrum, SERS spectrum, X-ray diffraction (XRD), Infrared spectrum (FT-IR), and EDX elemental mapping results revealed that the structural composition of the compound has good properties with localized surface plasmon resonance (LSPR) properties, high adsorption capacity, excellent SERS sensitivity and stability. When it was used as SERS substrate, the results of quantitative analysis of FM in pork showed a linear range of 0.10-50 mg·L^-1 with a correlation coefficient (R²) of 0.9819, the limit of detection (LOD) of 0.15 mg·g^-1, the recovery rate of 88.94%∼104.77%, the intra- and inter- batch relative standard deviation (RSD) of 3.57%∼14.22% and 0.18%∼3.44% respectively. Further verification results of the existing standard methods showed no significant difference between the SERS and UV methods (P < 0.05), as well as demonstrating that the SERS method has optimal precision, accuracy, and practicality. These results exposed that Au@MIL-100 (Fe) as a SERS substrate has great potential in rapid and on-site detection analysis.

Photodynamic therapy: Innovative approaches for antibacterial and anticancer treatments

Photodynamic therapy is an alternative treatment mainly for cancer but also for bacterial infections. This treatment dates back to 1900 when a German medical school graduate Oscar Raab found a photodynamic effect while doing research for his doctoral dissertation with Professor Hermann von Tappeiner. Unexpectedly, Raab revealed that the toxicity of acridine on paramecium depends on the intensity of light in his laboratory. Photodynamic therapy is therefore based on the administration of a photosensitizer with subsequent light irradiation within the absorption maxima of this substance followed by reactive oxygen species formation and finally cell death. Although this treatment is not a novelty, there is an endeavor for various modifications to the therapy. For example, selectivity and efficiency of the photosensitizer, as well as irradiation with various types of light sources are still being modified to improve final results of the photodynamic therapy. The main aim of this review is to summarize anticancer and antibacterial modifications, namely various compounds, approaches, and techniques, to enhance the effectiveness of photodynamic therapy.

Tuning Magnetic and Photophysical Properties of Luminomagnetic Metal-Organic Framework Composites in an Inverse Core-Satellite Structure

Luminomagnetic composites have been synthesized that allow for an individual tuning of luminescence intensity, chromaticity and magnetization by combination of superparamagnetic, citrate-stabilized iron oxide nanoparticles with the luminescent MOFs ³ _∞ [Ln₂ (BDC)₃ (H₂ O)₄ ] (Ln=Eu, Tb; BDC^2- =terephthalate). The components are arranged to a concept of inverse structuring compared to previous luminomagnetic composites with MOF@magnetic particle (shell@core) composition so that the luminescent MOF now acts as core and is covered by magnetic nanoparticles forming the satellite shell. Thereby, the magnetic and photophysical properties are individually tuneable between high emission intensity (1.2 ⋅ 10⁶  cps mg^-1 ) plus low saturation magnetization (6 emu g^-1 ) and the direct opposite (0.09 ⋅ 10⁶  cps mg^-1 ; 42 emu g^-1 ) by adjusting the particle coverage of the MOF. This is not achievable with a core-shell structure having a magnetic core and a dense MOF shell. The composition of the composites and the influence of different synthesis conditions on their properties were investigated by SEM/EDX, PXRD, magnetization measurements and photoluminescence spectroscopy.

Metal-organic frameworks as chemical nanoreactors for the preparation of catalytically active metal compounds

Since the emergence of metal-organic frameworks (MOFs), a myriad of thrilling properties and applications, in a wide range of fields, have been reported for these materials, which mainly arise from their porous nature and rich host-guest chemistry. However, other important features of MOFs that offer great potential rewards have been only barely explored. For instance, despite the fact that MOFs are suitable candidates to be used as chemical nanoreactors for the preparation, stabilization and characterization of unique functional species, that would be hardly accessible outside the functional constrained space offered by MOF channels, only very few examples have been reported so far. In particular, we outline in this feature recent advances in the use of highly robust and crystalline oxamato- and oxamidato-based MOFs as reactors for the in situ preparation of well-defined catalytically active single atom catalysts (SACS), subnanometer metal nanoclusters (SNMCs) and supramolecular coordination complexes (SCCs). The robustness of selected MOFs permits the post-synthetic (PS) in situ preparation of the desired catalytically active metal species, which can be characterised by single-crystal X-ray diffraction (SC-XRD) taking advantage of its high crystallinity. The strategy highlighted here permits the always challenging large-scale preparation of stable and well-defined SACs, SNMCs and SCCs, exhibiting outstanding catalytic activities.

A review on development of metal-organic framework-derived bifunctional electrocatalysts for oxygen electrodes in metal-air batteries

Worldwide demand for oil, coal, and natural gas has increased recently because of odd weather patterns and economies recovering from the pandemic. By using these fuels at an astonishing rate, their reserves are running low with each passing decade. Increased reliance on these sources is contributing significantly to both global warming and power shortage problems. It is vital to highlight and focus on using renewable energy sources for power production and storage. This review aims to discuss one of the cutting-edge technologies, metal-air batteries, which are currently being researched for energy storage applications. A battery that employs an external cathode of ambient air and an anode constructed of pure metal in which an electrolyte can be aqueous or aprotic electrolyte is termed as a metal-air battery (MAB). Due to their reportedly higher energy density, MABs are frequently hailed as the electrochemical energy storage of the future for applications like grid storage or electric car energy storage. The demand of the upcoming energy storage technologies can be satisfied by these MABs. The usage of metal-organic frameworks (MOFs) in metal-air batteries as a bi-functional electrocatalyst has been widely studied in the last decade. Metal ions or arrays bound to organic ligands to create one, two, or three-dimensional structures make up the family of molecules known as MOFs. They are a subclass of coordination polymers; metal nodes and organic linkers form different classes of these porous materials. Because of their modular design, they offer excellent synthetic tunability, enabling precise chemical and structural control that is highly desirable in electrode materials of MABs.

Rational Design of a Core-Shell Structured Plasmonic Au@MIL-100(Fe) Nanocomposite for Efficient Photocatalysis

The utilization of solar light to trigger organic syntheses for the production of value-added chemicals has attracted increasing recent research attention. The integration of plasmonic Au NPs (NPs = nanoparticles) with MOFs would provide a new way for the development of highly efficient photocatalytic systems. In this manuscript, a bottle-around-ship strategy was adopted for the successful synthesis of a core-shell structured Au_pvp@MIL-100(Fe) (PVP = polyvinylpyrrolidone) nanocomposite in room temperature. The as-obtained core-shell structured Au_pvp@MIL-100(Fe) show improved photocatalytic performance for benzyl alcohol oxidation under visible light, because of the migration of the surface plasmon resonance (SPR) excited hot electrons from plasmonic Au NPs to MIL-100(Fe), resulting in the production of more active O₂^•- radicals. The removal of the capping agent PVP from Au_pvp@MIL-100(Fe) significantly enhanced the photocatalytic performance, because of an improved charge transfer from plasmonic Au NPs to MIL-100(Fe). This study demonstrates an efficient strategy of fabricating superior photocatalytic systems by a rational coupling of plasmonic Au NPs and photocatalytic active MOFs into a core-shell structured nanocomposite.

Enhanced Catalytic Performance of a Ce/V Oxo Cluster through Confinement in Mesoporous SBA-15

To increase catalytic efficiency, mesoporous supports have been widely applied to immobilize well-defined metal oxide clusters due to their ability to stabilize highly dispersed clusters. Herein, a redox-active heterometallic Ce₁₂V₆-oxo cluster (CeV) was first presynthesized and then incorporated into mesoporous silica, SBA-15, via a straightforward impregnation method. Scanning transmission electron microscopy (STEM) and Fourier transform infrared spectroscopy (FTIR), in concert with scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), verified the successful introduction of the CeV cluster inside the pore of SBA-15. The ⁵¹V magic angle spinning solid-state nuclear magnetic resonance (⁵¹V MAS NMR) spectroscopy and differential pair distribution function (dPDF) analysis confirmed the structural integrity of the CeV cluster inside the SBA-15. The composite was then benchmarked for liquid-phase oxidation of 2-chloroethyl ethyl sulfide (CEES) under mild conditions and gas-phase oxidative dehydrogenation (ODH) of propane under high temperatures (up to 550 °C). The catalytic reactivity results demonstrated 8- and 14-fold increase in turnover frequency (TOF) values of the composite (CeV@10SBA-2) than the bulk CeV cluster under the same conditions for CEES oxidation and ODH, respectively. These results highlight the improved reactivity of the catalytically active CeV cluster as attributed to the higher dispersion of the discrete cluster upon immobilization within the SBA-15 support.

Recent developments in MOF and MOF based composite as potential adsorbents for removal of aqueous environmental contaminants

With the growth of globalization which has been the primary cause of water pollution, it is utmost necessary for us living being to have access to clean water for the purpose of drinking, washing and various other useful applications. With the purpose of future security and to restore our ecological balance, it is essential to give much significance towards the removal of unwanted toxic contaminants from our water resources. In this regard adsorptive removal of toxic pollutants from wastewater with porous adsorbent is regarded as one of the most promising way for water decontamination process. Metal organic frameworks (MOFs) comprising of uniformly arranged pores, abundant active sites and containing an easily tunable structure has aroused as a promising material for adsorbent to remove the unwanted contaminants from water sources. The adsorption of pollutants by the different MOFs surface are driven by various interactions including π-π, acid-base, electrostatic and H-bonding etc. On the other hand, the removal of various contaminants by MOFs is influenced by various factors including pH, temperature and initial concentration. In this review we will specifically discuss the adsorptive removal of different organic and inorganic pollutants present in our water systems with the use of MOFs as adsorbent along with the various factors and interaction mechanism manipulating the adsorption behaviour.

Nanoparticles Design for Theranostic Approach in Cancer Disease

Presently, there are no conclusive treatments for many types of cancer, mainly due to the advanced phase of the disease at the time of diagnosis and to the side effects of existing therapies. Present diagnostic and therapeutic procedures need to be improved to supply early detection abilities and perform a more specific therapy with reduced systemic toxicity. In this review, improvements in nanotechnology allowing the design of multifunctional nanoparticles for cancer detection, therapy, and monitoring are reported. Nanoparticles, thanks to the nanomaterials they are made of, can be used as contrast agents for various diagnostic techniques such as MRI, optical imaging, and photoacoustic imaging. Furthermore, when used as drug carriers, they can accumulate in tumor tissues through the passive or/and active targeting, protect encapsulated drugs from degradation, raise tumor exposure to chemotherapeutic agents improving treatment effects. In addition, nanocarriers can simultaneously deliver more than one therapeutic agent enhancing the effectiveness of therapy and can co-deliver imaging and therapy agents to provide integration of diagnostics, therapy, and follow-up. Furthermore, the use of nanocarriers allows to use different therapeutic approaches, such as chemotherapy and hyperthermia to exploit synergistic effects. Theranostic approach to diagnose and treat cancer show a great potential to improve human health, however, despite technological advances in this field, the transfer into clinical practice is still a long way off.

Removal of lead ions from aqueous solution using new magnetic metal-organic framework

In this research, new magnetic nanocomposites that consist of NH₂-MIL53 (Al) and Fe₃O₄ nanoparticles functionalized with cysteine were synthesized and characterized. The application of these nanocomposites was investigated to remove lead ions from the wastewater model. The concentration of metal ions was measured by the utilization of flame atomic absorption spectroscopy (FAAS). Also, XRD, SEM, EDX, and FTIR instruments were used to identification and characterization of the synthesized nanocomposites. The effect of operating parameters such as; pH, contact time and adsorbent dosage were investigated on lead removal. The synthesized nanocomposite showed great potential for lead removal. The maximum adsorption capacity of the nanocomposite was about 361.53 mg/g. Adsorption kinetic parameters well fitted with the pseudo-second order kinetic model. The reusability test of the synthesized magnetic absorbent showed good adsorption efficiency for at least three consecutive cycles.

Inhibitory Effect of Bi2O3NPs Produced by green synthesis method

Because of its medical and biological uses, green nanoparticle production has gotten a lot of attention. Bismuth oxide nanoparticles (Bi2O3 NP) were synthesized using aqueous extract from cocoa plants in this study, and the result was examined using an ultraviolet-visible, spectro-photometer, Fourier transform infrared, X-ray diffraction, and atomic force microscopy, The samples’ antibacterial activity was tested against a variety of microorganisms.

Biosynthesis of Sulphur Nanoparticles and discovering its effectiveness for some biological applications

In this research, sulfur nanoparticles were prepared using the plant synthesis method, and the particles were identified through biological equipment for the purpose of adding them for application purposes. The structural, surface, and optical properties of S-NPs were investigated. Transmittance and band gap were calculated using an optical approach to explore the optical properties. Surface and structural properties of the film were investigated using SEM micrographs and an X-ray diffraction pattern, respectively. The antibacterial and antifungal potential of S-NPs has been identified after extensive research.

Development and Investigation of High Performance PVA/NiO and PVA/CuO Nanocomposites with Improved Physical, Dielectric and Mechanical Properties

A series of polyvinyl alcohol (PVA)based composites with well dispersed nano fillers were fabricated and compared in terms of dielectric, mechanical, and optical properties. Specifically, NiO and CuO nano-fillers were utilized in a range of 0.2-0.6 wt% for thin film fabrication by solution deposition method. The characterization of nanocomposites was confirmed through FTIR, FESEM, and XRPD, whereas dielectric and mechanical properties were analyzed with respect to the filler concentrations. The bandgap of PVA/nano-filler composites reduced with an increase in NiO and CuO concentration from 0.2 to 0.6 wt%. The increase in the permittivity of the material was observed for 6 wt% of nano-fillers. The toughness of PVA/nano-filler composites was improved by increasing CuO and NiO concentration and Young's modulus of 30.9 and 27.2 MPa for 0.6 wt% of NiO and CuO-based nanocomposite, respectively, was observed. The addition of nano-fillers showed improved optical, dielectric, and mechanical properties.

Synthesis of Metal–Organic Frameworks Quantum Dots Composites as Sensors for Endocrine-Disrupting Chemicals

Hazardous chemical compounds such as endocrine-disrupting chemicals (EDCs) are widespread and part of the materials we use daily. Among these compounds, bisphenol A (BPA) is the most common endocrine-disrupting chemical and is prevalent due to the chemical raw materials used to manufacture thermoplastic polymers, rigid foams, and industrial coatings. General exposure to endocrine-disrupting chemicals constitutes a serious health hazard, especially to reproductive systems, and can lead to transgenerational diseases in adults due to exposure to these chemicals over several years. Thus, it is necessary to develop sensors for early detection of endocrine-disrupting chemicals. In recent years, the use of metal–organic frameworks (MOFs) as sensors for EDCs has been explored due to their distinctive characteristics, such as wide surface area, outstanding chemical fastness, structural tuneability, gas storage, molecular separation, proton conductivity, and catalyst activity, among others which can be modified to sense hazardous environmental pollutants such as EDCs. In order to improve the versatility of MOFs as sensors, semiconductor quantum dots have been introduced into the MOF pores to form metal–organic frameworks/quantum dots composites. These composites possess a large optical absorption coefficient, low toxicity, direct bandgap, formidable sensing capacity, high resistance to change under light and tunable visual qualities by varying the size and compositions, which make them useful for applications as sensors for probing of dangerous and risky environmental contaminants such as EDCs and more. In this review, we explore various synthetic strategies of (MOFs), quantum dots (QDs), and metal–organic framework quantum dots composites (MOFs@QDs) as efficient compounds for the sensing of ecological pollutants, contaminants, and toxicants such as EDCs. We also summarize various compounds or materials used in the detection of BPA as well as the sensing ability and capability of MOFs, QDs, and MOFs@QDs composites that can be used as sensors for EDCs and BPA.

Single-step Green Synthesis of Gold Conjugated Polyphenol Nanoparticle Using Extracts of Saudi’s myrrh: Their Characterization, Molecular Docking and Essential Biological Applications

•

This work used C.myrrh aqueous extract as a reducing and capping agent for GNPs.

•

The GNPs were synthesized in a single step and possessed a spherical shape.

•

The synthesized GNPs exhibited anti-diabetic, anti-cancer, anti-inflammation, and anti-bacterial activities.

The progress in the innovative nanocrystal synthesis process by using environmentally benign and low-priced nontoxic chemicals, solvents, and renewable sources remains a challenging task for researchers worldwide. The majority of the existing synthesis techniques engage in the potentially dangerous, for either human health or the environment. Current investigation has been centered on green synthesis processes to create novel nanomaterials, which are eco-friendly as well as safer for sustainable marketable feasibility. The current work provides the green synthesis method for gold nanoparticle (GNPs) synthesis using Commiphora myrrh (C.myrrh) extract. This simple method includes 6 ml of HAuCl₄·3H₂O treated with 4 ml C.myrrh extract having pH 4.5 after 80 min at 25 °C temperature. In this novel method, green synthesized GNPs characterized by UV–Vis, X^_ray diffraction spectroscopy (XRD), zeta potential, fourier transform infrared (FT^_IR), high^_resolution transmission electron microscopy (HR^_TEM), energy dispersive X^_ray spectroscopy (EDXA), and dynamic light scattering (DLS). During the development successful antioxidant assay, the DPPH assay was applied. The cell toxicity of green synthesized GNPs was evaluated following an MTT assay against HCT-116 (colon cancer) and MCF-7 (breast cancer).

Besides molecular docking in the δ-elemene for inhibitor to VEGFR‐2 domain revealed more negative docking score (−3.976) which is an excellent binding affinity to the C.myrrh@GNP. The synthesized GNPs showed antidiabetic, antibiotic, and antibacterial properties and anti^_inflammatory inhibition against inhibiting COX-1, and COX-2 enzymes. In addition, molecular docking by Lindestrene (−3.806) and Furanoeudesma-1,3-dien (−3.912) against COX1 and COX2 respectively showed strong binding affinity. The molecular docking study evidenced the anti-inflammatory and cell toxicity study.

Characterization and Antibacterial Evaluation of Biodegradable Mannose-Conjugated Fe-MIL-88NH2 Composites Containing Vancomycin against Methicillin-Resistant Staphylococcus aureus Strains

The emergence of bacterial resistance has increased the economic burden of infectious diseases dramatically during the previous few decades. Multidrug resistance (MDR) is difficult to cure in both Gram-negative and positive bacteria and is often incurable with traditional and broad-range antibiotics. Therefore, developing techniques to increase the antibacterial activity of therapeutic drugs is essential. Metal-organic frameworks (MOFs) are extremely versatile hybrid materials made of metal ions coupled via organic bridging ligands. They have been widely used as an excellent vehicle for drug delivery due to their low toxicity, biodegradability, and structural stability upon loading and functionalization. The present study focused on the synthesis of mannose (MNS)-coated MOFs with enhanced surface contact with S. aureus cells. The MNS coating on the surface of MOFs enhances their adherence to bacteria by binding to lectins present on the bacterial cell, resulting in improved VCM cellular penetration and activity against resistant bacteria. Various techniques, including atomic force microscopy, DLS, TGA, FT-IR, and DSC, were employed to analyze MNS-coated MOFs. They were also evaluated for their efficacy against resistant S. aureus. The results indicated that when VCM was loaded into MNS-coated MOFs, their bactericidal activity rose dramatically, resulting in the greater suppression of resistant S. aureus. AFM investigation of S. aureus strains demonstrated total morphological distortion after treatment with MNS-coated drug-loaded MOFs. The results of this work suggest that MNS-coated MOFs may be effective for reversing bacterial resistance to VCM and open new pathways for improving antibiotic therapy for diseases associated with MDR.

Five-FU@CuS/NH2 -UiO-66 as a drug delivery system for 5-fluorouracil to colorectal cancer cells

In this study, copper sulfide nanoparticles (CuS-NPs), which can improve the antiproliferative properties of conventional anticancer drugs such as 5-fluorouracil (5-FU), were incorporated into the pores of amine-functionalized UiO-66 (CuS/NH₂ -UiO-66). The introduced nano-drug delivery system was exerted to perform an in vitro treatment on CT-26 mouse colorectal cancer cells. The synthesized final product was labeled as 5-FU@CuS/NH₂ -UiO-66 and characterized through conventional methods including X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) analysis, Ultraviolet-Visible (UV-Vis) analysis, Inductively coupled plasma mass spectrometry (ICP-MS), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In contrast to 5-FU, the outcomes of the cytotoxicity assay lacked any comparable results for 5-FU@CuS/NH₂ -UiO-66.

Innovative electrochemical electrode modified with Al2O3 nanoparticle decorated MWCNTs for ultra-trace determination of tamsulosin and solifenacin in human plasma and urine samples and their pharmaceutical dosage form

A simple, cheap, sensitive, and time-saving square wave voltammetric (SWV) procedure using a carbon paste electrode modified with aluminum oxide nanoparticle decorated multi-walled carbon nanoparticles (Al₂O₃-NPs/MWCNTs/CPE) is presented for the ultra-sensitive determination of tamsulosin (TAM) and solifenacin (SOL), one of the most prescribed pharmaceutical combinations in urology. Characterization of the developed electrode was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD) patterns, energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM) and FT-IR spectrophotometry. The voltammetric behavior of TAM/SOL was evaluated using Al₂O₃-NPs in different content and electrode compositions. The use of Al₂O₃ functionalized MWCNTs as a CPE modifier increased the process of electron transfer as well as improved the electrode active surface area therefore, ultra-sensitive results were acquired with a linear range of 10–100 and 12–125 ng ml⁻¹ for TAM and SOL respectively, and a limit of the detection value of 2.69 and 3.25 ng ml⁻¹ for TAM and SOL, respectively. Interestingly, the proposed method succeeded in quantifying TAM and SOL with acceptable percentage recoveries in dosage forms having diverged concentration ranges and in the biological fluids with very low peak plasma concentration (C_max). Furthermore, the proposed method was validated, according to the ICH criteria, and shown to be accurate and reproducible.

A SWV method using a carbon paste electrode modified with aluminum oxide nanoparticle-decorated multi-walled carbon nanoparticles is presented for ultra-sensitive determination of tamsulosin and solifenacin, one of the most prescribed pharmaceutical combinations in urology.

Functionalization of 2D MoS2 Nanosheets with Various Metal and Metal Oxide Nanostructures: Their Properties and Application in Electrochemical Sensors

Two-dimensional transition metal dichalcogenides (2D TMDs) have gained considerable attention due to their distinctive properties and broad range of possible applications. One of the most widely studied transition metal dichalcogenides is molybdenum disulfide (MoS₂). The 2D MoS₂ nanosheets have unique and complementary properties to those of graphene, rendering them ideal electrode materials that could potentially lead to significant benefits in many electrochemical applications. These properties include tunable bandgaps, large surface areas, relatively high electron mobilities, and good optical and catalytic characteristics. Although the use of 2D MoS₂ nanosheets offers several advantages and excellent properties, surface functionalization of 2D MoS₂ is a potential route for further enhancing their properties and adding extra functionalities to the surface of the fabricated sensor. The functionalization of the material with various metal and metal oxide nanostructures has a significant impact on its overall electrochemical performance, improving various sensing parameters, such as selectivity, sensitivity, and stability. In this review, different methods of preparing 2D-layered MoS₂ nanomaterials, followed by different surface functionalization methods of these nanomaterials, are explored and discussed. Finally, the structure-properties relationship and electrochemical sensor applications over the last ten years are discussed. Emphasis is placed on the performance of 2D MoS₂ with respect to the performance of electrochemical sensors, thereby giving new insights into this unique material and providing a foundation for researchers of different disciplines who are interested in advancing the development of MoS₂-based sensors.

Recent Advances in the Application and Mechanism of Carbon Dots/Metal-Organic Frameworks Hybrids in Photocatalysis and the Detection of Environmental Pollutants

Metal-organic frameworks (MOFs) are a class of crystalline porous materials with simple synthesis conditions, large specific surface area, structural diversity, and a wide range of interesting properties. The integration of MOFs with other materials can provide new multifunctional composites that exhibit both component properties and new characteristics. In recent years, the integration of carbon dots (CDs) into MOFs to form composites has shown improved optical properties and fascinating new characteristics. This review focuses on the design and synthesis strategies of CDs@MOFs composites (including pore-confined synthesis, in situ encapsulation, post-synthesis modification and impregnation method) and their recent research progress in photocatalysis and detection of environmental pollutants. Both the achievements and problems are evaluated and proposed, and the opportunities and challenges of CDs@MOF composite are discussed.

Thermocatalytic Hydrogenation of CO2 to Methanol Using Cu-ZnO Bimetallic Catalysts Supported on Metal–Organic Frameworks

The thermocatalytic hydrogenation of carbon dioxide (CO2) to methanol is considered as a potential route for green hydrogen storage as well as a mean for utilizing captured CO2, owing to the many established applications of methanol. Copper–zinc bimetallic catalysts supported on a zirconium-based UiO-66 metal–organic framework (MOF) were prepared via slurry phase impregnation and benchmarked against the promoted, co-precipitated, conventional ternary CuO/ZnO/Al2O3 (CZA) catalyst for the thermocatalytic hydrogenation of CO2 to methanol. A decrease in crystallinity and specific surface area of the UiO-66 support was observed using X-ray diffraction and N2-sorption isotherms, whereas hydrogen-temperature-programmed reduction and X-ray photoelectron spectroscopy revealed the presence of copper active sites after impregnation and thermal activation. Other characterisation techniques such as scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis were employed to assess the physicochemical properties of the resulting catalysts. The UiO-66 (Zr) MOF-supported catalyst exhibited a good CO2 conversion of 27 and 16% selectivity towards methanol, whereas the magnesium-promoted CZA catalyst had a CO2 conversion of 31% and methanol selectivity of 24%. The prepared catalysts performed similarly to a CZA commercial catalyst which exhibited a CO2 conversion and methanol selectivity of 30 and 15%. The study demonstrates the prospective use of Cu-Zn bimetallic catalysts supported on MOFs for direct CO2 hydrogenation to produce green methanol.

Advanced Metal–Organic Frameworks-Based Catalysts in Electrochemical Sensors

Developing efficient catalysts is vital for the application of electrochemical sensors. Metal–organic frameworks (MOFs), with high porosity, large specific surface area, good conductivity, and biocompatibility, have been widely used in catalysis, adsorption, separation, and energy storage applications. In this invited review, the recent advances of a novel MOF-based catalysts in electrochemical sensors are summarized. Based on the structure–activity–performance relationship of MOF-based catalysts, their mechanism as electrochemical sensor, including metal cations, synthetic ligands, and structure, are introduced. Then, the MOF-based composites are successively divided into metal-based, carbon-based, and other MOF-based composites. Furthermore, their application in environmental monitoring, food safety control, and clinical diagnosis is discussed. The perspective and challenges for advanced MOF-based composites are proposed at the end of this contribution.

Understanding the Working Mechanism of the NovelHKUST-1@BPS Composite Materials as Stationary Phases for Liquid Chromatography

Composite materials have been used based on coordination polymers or microporous metal-organic frameworks (MOFs) combined with mesoporous matrices for adsorption-related techniques, which enable outflanking some adverse phenomena manifested during pristine components operation and enhance the performance and selectivity of the resulting materials. In this work, for the first time, the novel HKUST-1@BPS composites synthesized by the microwave-assisted (MW) technique starting from microporous HKUST-1 (Cu₃(btc)₂) MOF and biporous silica matrix (BPS) with bimodal mesopore size distribution were comparatively studied as materials for liquid-phase adsorption techniques utilizing the high-performance liquid chromatography (HPLC) method and benzene as a model adsorbate. It was established that the studied HKUST-1@BPS composites can function as stationary phases for HPLC, unlike the pristine HKUST-1 and bare BPS materials, due to the synergetic effect of both components based on the preliminary enhanced adsorbate mass transfer throughout the silica mesopores and, subsequently, its penetrating into HKUST-1 micropores. The suggested mechanism involves the initial deactivation of open metal Cu²⁺ sites in the HKUST-1 framework structure by isopropanol molecules upon adding this polar component into the mobile phase in the region of the isopropanol concentration of 0.0 to 0.2 vol.%. Thereafter, at the medium range of varying the isopropanol concentration in the eluent of 0.2 to 0.3 vol.%, there is an expansion of the previously inaccessible adsorption centers in the HKUST-1@BPS composites. Subsequently, while further increasing the isopropanol volume fraction in the eluent in the region of 0.3 to 5.0 vol.%, the observed behavior of the studied chromatographic systems is similar to the quasi-normal-phase HPLC pattern. According to the obtained thermodynamic data, benzene adsorption into HKUST-1 micropores from solutions with a vol.% of isopropanol in the range of 0.4 to 5.0 follows the unique entropy-driven mechanism previously described for the MIL-53(Al) framework. It was found that HKUST-1 loading in the composites and their preparation conditions have pronounced effects on their physicochemical properties and adsorption performance, including the adsorption mechanism.