Zeolitic Imidazolate Framework Research Articles

Nano-enzyme hydrogels for cartilage repair effectiveness based on ternary strategy therapy.

Designing artificial nano-enzymes for scavenging reactive oxygen species (ROS) in chondrocytes (CHOs) is considered the most feasible pathway for the treatment of osteoarthritis (OA). However, the accumulation of ROS due to the amount of nano-enzymatic catalytic site exposure and insufficient oxygen supply seriously threatens the clinical application of this therapy. Although metal-organic framework (MOF) immobilization of artificial nano-enzymes to enhance active site exposure has been extensively studied, artificial nano-enzymes/MOFs for ROS scavenging in OA treatment are still lacking. In this study, a biocompatible lubricating hydrogel-loaded iron-doped zeolitic imidazolate framework-8 (Fe/ZIF-8/Gel) centrase was engineered to scavenge endogenous overexpressed ROS synergistically generating dissolved oxygen and enhancing sustained lubrication for CHOs as a ternary artificial nano-enzyme. This property enabled the nano-enzymatic hydrogels to mitigate OA hypoxia and inhibit oxidative stress damage successfully. Ternary strategy-based therapies show excellent cartilage repair in vivo. The experimental results suggest that nano-enzyme-enhanced lubricating hydrogels are a potentially effective OA treatment and a novel strategy.

Adsorption properties of n-octane/1-octene binary mixtures in the zeolitic imidazolate frameworks, ZIF-8 and ZIF-67: Combined experimental and molecular simulation study

1-Octene, a linear α-olefin, can be used as a comonomer for producing plastics, oils, waxes, and surfactants. High-purity 1-octene can be obtained by removing paraffin byproducts using energy-intensive distillation. Adsorptive separation using porous material–based adsorbents is a promising alternative to distillation. Most reported adsorbents are zeolites, which preferentially adsorb 1-octene rather than n-octane owing to their polar framework. However, the existing studies are insufficient for investigating apolar adsorbents that adsorb more amounts of n-octane than 1-octene. Herein, the adsorption properties of the apolar adsorbents, zeolitic imidazolate frameworks-8 (ZIF-8) and ZIF-67, obtained from a n-octane/1-octene liquid binary mixture were systematically investigated by conducting batch adsorption experiments for the n-octane volume fraction of 10 %–90 %. Results show that ZIF-8 and ZIF-67 are promising adsorbents for the selective adsorption of n-octane owing to the preferential adsorption of n-octane in the micropores of the ZIFs at the high concentration of n-octane. Configurational-bias grand canonical Monte Carlo simulations confirm that the host–adsorbate energy between ZIF-8 and n-octane is higher than that between ZIF-8 and 1-octene, whereas the host–adsorbate energy between ZIF-67 and n-octane is similar to that between ZIF-67 and 1-octene.

Designing Dual-Responsive Drug Delivery Systems: The Role of Phase Change Materials and Metal–Organic Frameworks

Abstract: Stimuli-responsive drug delivery systems (DDSs) offer precise control over drug release, enhancing therapeutic efficacy and minimizing side effects. This review focuses on DDSs that leverage the unique capabilities of phase change materials (PCMs) and metal–organic frameworks (MOFs) to achieve controlled drug release in response to pH and temperature changes. Specifically, this review highlights the use of a combination of lauric and stearic acids as PCMs that melt slightly above body temperature, providing a thermally responsive mechanism for drug release. Additionally, this review delves into the properties of zeolitic imidazolate framework-8 (ZIF-8), a stable MOF under physiological conditions that decomposes in acidic environments, thus offering pH-sensitive drug release capabilities. The integration of these materials enables the fabrication of complex structures that encapsulate drugs within ZIF-8 or are enveloped by PCM layers, ensuring that drug release is tightly controlled by either temperature or pH levels, or both. This review provides comprehensive insights into the core design principles, material selections, and potential biomedical applications of dual-stimuli responsive DDSs, highlighting the future directions and challenges in this innovative field.

A multifunctional injectable hydrogel for boosted diabetic wound healing assisted by Quercetin-ZIF system

An important challenge in the chronic wound healing of diabetes is delayed healing stages with impaired cellular functions, attributed to mitochondrial dysfunction and excessive endoplasmic reticulum (ER) stress. Here, we describe a quercetin (QCT)-loaded zeolitic imidazolate framework (ZIF-8) incorporated into a polyphenol-mediated carboxymethyl chitosan/tannic acid (CT) dynamic hydrogel to promote diabetic wound healing by regulating subcellular and cellular functions. ZIF-8 endows the hydrogel with excellent antibacterial properties. By alleviating mitochondrial function and ER stress, the hydrogel fundamentally improves the cellular function damage induced by hyperglycemia and is endowed with reactive oxygen species (ROS)-scavenging and anti-apoptosis activities to promote cell proliferation, extension and keratinocyte differentiation. Moreover, sustained release of QCT and Zn2+ from the QCT@ZIF-8 system not only promotes vascular endothelial cell migration but also alleviates tubular dysfunction, thus achieving excellent angiogenesis. Accordingly, these features create a favorable environment for skin regeneration and synergistically accelerate diabetic wound healing. Therefore, our findings reveal a potential multi-effect therapeutic strategy for diabetic wound healing. Potential design principles targeting subcellular and cell function open up new avenues for other metabolic and inflammatory diseases.

Metal-Organic framework incorporated luminescent PTCA combined with novel co-reactant accelerator for ultra-sensitive electrochemiluminescence detection of CA19-9

Polycyclic aromatic hydrocarbons (PAHs) are commonly used as electrochemiluminescence (ECL) luminophores. However, PAHs are limited by the aggregation-caused quenching (ACQ) effect, which reduces ECL emission. Therefore, developing an ECL system from PAHs with efficient luminescence is a significant challenge. In this work, a two-ligand strategy was proposed to assemble 3, 4, 9, 10-perylenetetracarboxylic acid (PTCA) into zeolitic imidazole framework-8 (ZIF-8). The ACQ effect of PTCA was inhibited by participating in the formation of metal–organic frameworks (MOFs) and a luminescent ZIF-8-PTC (Z8P) composite was obtained. Satisfactorily, conceptual experiments demonstrated that the significantly higher ECL efficiency of Z8P was achieved compared with PTCA monomers and aggregates. On the sensing substrate, a novel co-reactant accelerator (Au@MFNC) was used to achieve continuous catalysis of the persulfate (K2S2O8) with the Prussian blue analogues (PBAs) as a template under the efficient synergistic effect of MoS2. Through the reversible transformation of the transition metal valence states, a sufficient amount of sulfate radicals (SO4•−), again amplifying the ECL signal of Pd@Z8P. Under ideal conditions, the constructed dual-MOFs ECL immunosensor had a wide response range (1 × 10−4 − 1 × 102 U/mL) and a low limit of detection (LOD) (6 × 10−5 U/mL), which provided an alternative method for CA19-9 ultrasensitive detection, and broadened a new idea for the development of high-performance luminescent MOFs.

Half etching of ZIF-67 towards open hollow nanostructure with boosted absorption ability for toxic smoke and fume in epoxy composites

Metal-organic frameworks (MOFs) are favored in the field of flame retardancy due to the catalytic effect of metal nodes on char layer formation and the synergistic flame-retardant effect of organic ligands containing elements such as nitrogen and phosphorus. However, the inherent microporosity of MOFs limits their adsorption efficiency for toxic smoke and flammable gases. In this work, an organic phosphorus-modified MOF with a distinctive nanostructure of hierarchically porous (P-Co-MOF/ZIF) was successfully synthesized. In brief, an amino-functionalized zeolitic imidazolate framework (NH2-ZIF) was initially synthesized through a ligand substitution reaction with ZIF-67. Subsequently, organic phosphorus flame retardants were grafted on NH2-ZIF, and the acidic substances generated during this process were used to synchronously half etch ZIF, resulting in a ZIF with a high specific surface area and unique nanostructure. Through this simple synthetic method, the catalytic ability of transition metals in ZIF is preserved, and organic phosphorus flame retardants are incorporated into ZIF, resulting in the synergistic flame-retardant effect of phosphorus and nitrogen. Additionally, its unique hierarchically porous nanostructure can effectively enhance the adsorption of volatile products during the combustion process, thereby offering outstanding flame retardancy and smoke suppression effects for epoxy resin (EP). The results indicate that adding 2 wt% P-Co-MOF/ZIF to EP can increase the limiting oxygen index value to 29.5%. Furthermore, the peak of heat release rate, total heat release, and total smoke production of the composite material can decrease by 43.3%, 37.9%, and 38.1%, respectively, compared to EP. Therefore, this work will provide new inspiration for designing functional nanostructures and synthesizing efficient flame retardants.

Sn Nanoclusters Confined in COP‐Derived Carbon for Catalytic Oxygen Reduction Reaction

AbstractThe development of catalysts composed of single atoms is crucial for enhancing the performance of oxygen reduction reaction (ORR). However, the unsatisfactory intrinsic activity of these catalysts still poses a major challenge, limiting their overall effectiveness. One approach to addressing this challenge is the introduction of metal clusters, which can form a synergistic effect with the single atoms, ultimately improving their performance. In this study, core‐shell structured carbon polymer is constructed with Zn atoms and Sn nanoclusters by directly subjecting pyrolysis of the covalent organic polymer (COP) and metal organic framework (MOF) (COP@MOF). The thin COP shell serves a dual purpose: it prevents the collapse and aggregation of zeolitic imidazolate framework‐8 (ZIF‐8) and promotes the formation of mesopores, facilitating mass transport and enhancing the graphitization degree to improve conductivity. The resulting Sn‐COP@MOF800 exhibits promising catalytic performance in the ORR, demonstrating a half‐wave potential of 0.81 V and current density of 5.56 mA cm−2 in 0.1 m KOH, which is comparable to that of Pt/C. This study provides new ideas for exploring the application of metal single atoms and metal nanoclusters in ORR catalysis through synergistic effects.

Structural Origin of the Deformation Propensity of Zeolitic Imidazolate Framework Glasses

Structural Origin of the Deformation Propensity of Zeolitic Imidazolate Framework Glasses

Fluorescence sensing probe based on functionalized mesoporous MOFs for non-invasive and detection of dopamine in human fluids

Abnormal amount of dopamine (DA) in human body is closely relate to various diseases, such as Parkinson's disease, pheochromocytoma. Real-time monitoring DA is crucial for disease warning, diagnosis and treatment. Currently, most methods rely on invasive blood testing for detecting DA, which is only completed with the aid of the medical staffs in hospitals. Herein, a non-invasive fluorescence visual strategy is developed for the real-time monitoring DA, based on luminescent nanoparticles and modified mesoporous zeolite imidazole framework (ZIF-8-NH2) dodecahedrons. During the reaction process, DA is enriched through the spatial configuration of ZIF-8-NH2 and hydrogen bonding effect. The luminescence of Cr3+-doped zinc gallate (ZnGa2O4:Cr3+, ZGC) is inhibited by the photo-induced electron transfer (PET) mechanism to realize sensitively detecting DA. The intelligent sensing platform based on the designed fluorescence probe and color recognition system is structured for real-time detection of DA in urine. Furthermore, a skin-fitting hydrogel patch is prepared by combining a fluorescent probe with chitosan, which enables sensitive and accurate detection of DA in sweat without the complex sample pretreatment. The non-invasive fluorescence detection method provides an effective strategy for quantitatively monitoring DA in human fluids.

Photocatalytic performance and mechanism insights of an S-scheme ZnMn2O4/ZIF-67 heterostructure in photocatalytic CO2 reduction under visible light irradiation

Improved separation among photoelectrons and holes (e−, h+) and regulated electron transport routes are essential to improve photocatalytic performance. This work adopts a convenient but more efficient method to prepare an S-scheme composite photocatalyst integrating narrow band gap semiconductor ZnMn2O4 (ZMO) and zeolitic imidazole framework ZIF-67(Z67) for improved photocatalytic CO2 reduction. The designed photocatalyst ZMO(X)/Z67 showed more visible light harvesting capacity compared to individual ZMO and Z67. The ZMO/Z67 nanocomposite containing 3 % ZMO nanosphere produced 1.91 times higher methanol (48.64 μmolg−1) compared to pure Z67 (25.36 μmolg−1) and 1.42 times higher ethanol (30.32 μmolg−1) compared to pure Z67 (21.28 μmolg−1) after 8 h visible light illumination. The composites' increased photocatalytic performance might be attributed primarily to excellent photogenerated charge separation and transfer via the linked S-scheme heterojunction between ZMO nanospheres and Z67. Various characterization methods are used to explore the structural, morphological, optical, and electrochemical features of produced photocatalysts, and a thorough photocatalytic mechanism is provided. After four recycling, the composite photocatalyst demonstrated good stability and recyclability. This study attributed to a viable method for constructing a direct S-scheme heterojunction for photocatalytic CO2 reduction.

Decorated and sculpted zeolitic imidazolate frameworks for electrocatalytic carbon dioxide reduction to formate

The production of value-added chemicals using electrocatalytic CO2 reduction (ECR) is an effective strategy to achieve “carbon neutrality”. However, highly formate-selective production with zinc-based catalysts in ECR systems remains a challenge. In this work, a macroporous hollow nanocage structure was successfully created through the etching of zeolitic imidazolate frameworks (ZIFs) using phytic acid (PA). The surface of the hollow nanocage was then adorned, leading to the formation of a hybrid superstructure product (ZIF-P5/In) with a substantial surface area, enabling effective ECR to formate. The Faraday efficiency of ZIF-P5/In for formate is 80.2 % at −1.26 VRHE. This feasible strategy is expected to provide new insights into the preparation of highly efficient ZIF-derived electrocatalysts.

Cobalt nanoparticles confined nitrogen–doped carbon integrated bimetallic Co2P–VP heterostructured composite: A MOF integrated 3D arrays for catalytic water splitting

A robust electrode material with outstanding stability at high current density is crucial for the practical application of water splitting. We present an intertwined heterostructure composed of in-situ confined cobalt nanoparticles (Conp) in nitrogen-doped carbon (N–C), derived from functionalized zeolitic imidazolate framework–67 (ZIF−67), and composited with the hetero phase bimetallic cobalt vanadium phosphide (Co2P−VP) through a hydrothermal reaction, room temperature aging, and chemical vapor deposition (CVD) for simultaneous phosphidation, graphitization, and reduction. The synergistic effect generated across the multiple heterointerfaces of Co2P, VP, and Conp in the N−doped carbon on nickel foam, as the Co2P–VP@N–C/Co heterostructure, exhibits outstanding electrocatalytic performance for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and electrochemical water splitting. The Co2P–VP@N–C/Co (+,−) alkaline electrolyzer demonstrates a low potential of 1.49 and 1.71 V to achieve current densities of 10 and 100 mA cm−2, respectively. It exhibits outstanding stability during continuous operation for 100 h at 100 mA cm−2, with 98.02 % retention. The outstanding performance is credited to the synergistic interaction and d-electronic modulation of the metallic hetero phasic Co2P–VP moiety and confined Conp in a functionalized N−doped porous carbonaceous heterostructure. Density Functional Theory (DFT) validates the regulation of electronic structure for efficient redistribution of local charges and electron transfer.

Designing a MOF-functionalized Nanofibrous Aerogel via Vapor-Phase Synthesis.

Designing 3D mechanically robust and high-surface-area substrates for uniform and high-density deposition of metal-organic frameworks (MOFs) provide a promising strategy to enhance surface accessibility and application of these highly functional materials. Nanofibrous aerogel (NFA) with its highly porous self-supported structure composed of interconnected nanofibrous network offers an ideal platform in this regard. Herein, a facile one-pot strategy is introduced, which utilizes direct deposition of MOF on the nanofibrous surface of the NFAs. NFAs are synthesized using electrospun polyacrylonitrile/polyvinylpyrrolidone (PAN/PVP) polymer nanofibers containing zinc acetate (Zn(Ac)2), which are subjected to freeze drying and thermal treatment. The latter converts Zn(Ac)2 to zinc oxide (ZnO), providing the sites for MOF growth while also adding mechanical integrity to the NFAs through cyclization of the PAN. Exposure of the NFA to the vapor-phase of organic ligand, 2-methylimidazole (2-MeIm) enables in situ growth of zeolitic imidazolate framework-8 (ZIF-8) MOF on the NFA. ZIF-8 loading on the NFAs is further improved by more than tenfold by synthesizing ZnO nanorods/protrusions on the nanofibers, which enables more sites for MOF growth. These findings underscore a significant advancement in designing MOF-based hybrid aerogels, offering a streamlined approach for their use in diverse applications, from catalysis to sensing and water purification.

Application of Langmuir and Freundlich isotherm, pseudo-first-order, and pseudo-second-order kinetic studies for the adsorption of sunset yellow dye onto Cadmium-based imidazole zeolite nanostructure

ABSTRACT Zeolitic-imidazole framework (Cd-ZIF) was synthesised and characterised. Cd-ZIF was accomplished by Fourier transfer infrared (FTIR), field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD), energy-dispersive spectrum (EDX), and Brunauer–Emmett–Teller (BET). The synthesised zeolite was used in the (SY) adsorption. The impact of different variables on batch method as a function of solution pH, concentration of SY, dose of Cd-ZIF, contact time and temperature were analysed and optimal conditions were determined. The point of the zeolite zero charge (pHPZC) was obtained at 7.0. The optimal conditions were obtained at pH = 5, the initial concentration C 0 = 160 mg L−1, 30 mg of Cd-ZIF, t = 60 min, and 40°C. Langmuir and Freundlich models were employed by equilibrium data from SY adsorption process. The results showed that Freundlich model was fitted. Therefore, the adsorbent had a surface heterogeneity. The adsorption capacity increased with increasing the temperature up to 40°C, which showed the endothermic adsorption. Further temperature (at 45°C), the adsorption decreased because of electrostatic attraction between free and adsorbed SY molecules. The kinetics of adsorption indicated that SY adsorption followed a pseudo-second-order model and chemisorption.

Enhancing cellulose hydrolysis via cellulase immobilization on zeolitic imidazolate frameworks using physical adsorption.

This study investigates the immobilization of cellulase on zeolitic imidazolate frameworks (ZIFs) by physical adsorption, specifically the ZIF-8-NH2 and Fe3O4@ZIF-8-NH2, to enhance enzymatic hydrolysis efficiency. The immobilization process was thoroughly analyzed, including optimization of conditions and characterization of ZIF carriers and immobilized enzymes. The impacts on the catalytic activity of cellulase under various temperatures, pH levels, and storage conditions were examined. Additionally, the reusability of the immobilized enzyme was assessed. Results showed the cellulase immobilized on Fe3O4@ZIF-8-NH2 exhibited a high loading capacity of 339.64 mg/g, surpassing previous studies. Its relative enzymatic activity was found to be 71.39%. Additionally, this immobilized enzyme system demonstrates robust reusability, retaining 68.42% of its initial activity even after 10 cycles. These findings underscore the potential of Fe3O4@ZIF-8-NH2 as a highly efficient platform for cellulase immobilization, with promising implications for lignocellulosic biorefinery.

PH/redox-responsive release of interleukin-4 from ZIF-8@diselenide block copolymer to regulate inflammation

Multi-responsive drug-delivery systems have been widely explored to enable specific delivery to target sites. Here, interleukin-4 (IL-4), an anti-inflammatory cytokine, is first encapsulated in situ inside a zeolitic imidazolate framework (ZIF-8) to form IL-4@ZIF-8, which is subsequently coated with a diselenide block copolymer to obtain IL-4@ZIF-8@Se-Se-polymer. This delivery system enables redox-responsive release of IL-4 by the diselenide copolymer and a pH-triggered release by ZIF-8. Moreover, IL-4 release is precisely controlled stepwise by the stimuli response, with the dissociation of the diselenide copolymer, and breakdown of the ZIF-8 structure. The targeted release property of the IL-4@ZIF-8@Se-Se-polymer endows the materials with efficient macrophage immune regulation, as systematically demonstrated in vitro. This study provides an effective example of the delivery and on-demand release of IL-4, and may find promising applications in tissue engineering for the management of inflammation.

Synthesis and High-Pressure and Guest-Mediated Gate-Opening, Breathing, and Phase Transitions of Heterolinker Zeolitic Imidazolate Framework ZIF-60 Derivatives

Synthesis and High-Pressure and Guest-Mediated Gate-Opening, Breathing, and Phase Transitions of Heterolinker Zeolitic Imidazolate Framework ZIF-60 Derivatives

Correction to “Ni-Loaded 2D Zeolitic Imidazolate Framework as a Heterogeneous Catalyst with Highly Activity for Ethylene Dimerization”

Correction to “Ni-Loaded 2D Zeolitic Imidazolate Framework as a Heterogeneous Catalyst with Highly Activity for Ethylene Dimerization”

A networked iron and nitrogen-doped ZIF-8/MWCNTs heterostructure for oxygen reduction reaction.

Zeolitic Imidazolate Frameworks-8 (ZIF-8) is commonly used as an ideal precursor for non-noble metal catalysts because of its high specific surface area, ultra-high porosity, and N-rich content. Upon pyrolyzing ZIF-8 at 900 °C in Ar, the resulting material, referred to as Z8, displayed good activity toward the oxygen reduction reaction (ORR). Then the ZIF-8 was mixed with various conductive carbon materials, such as multiwall carbon nanotubes (MWCNTs), Acetylene black (ACET), Vulcan XC-72R (XC-72R), and Ketjenblack EC-600JD (EC-600JD), to form Z8 composites. The Z8/MWCNTs composite exhibited enhanced ORR activity owing to its network structure, meso-/microporous hierarchical porous structure, improved electrical conductivity, and graphitization. Subsequently, iron and nitrogen co-doping is achieved through the pyrolysis of a mixture comprising Fe, N precursor, and ZIF-8/MWCNTs, which is denoted as FeN-Z8/MWCNTs. The intrinsically high electrical conductivity of MWCNTs facilitated efficient electron transfer during the ORR, while the meso-/microporous hierarchical porous structure and network structure of Fe, N co-doped ZIF-8/MWCNTs promoted oxygen transport. The presence of Fe-containing species in the catalyst acted as activity centers for ORR. This strategy of preparing Z8 composites and modifying them with Fe, N co-doping offers an insightful approach to designing cost-effective electrocatalysts.

Cellulose nanocrystals mediated spontaneous weaving of ZIF-67 hybrid networks: Enhanced peroxymonosulfate activation and rapid removal of dye

Inter-connected zeolite imidazolate framework-67 (ZIF-67) hybrid networks were successfully synthesized by a cellulose nanocrystals (CNCs) mediated spontaneous weaving strategy, which was denoted as ZIF-67@CNC, and was applied to activate peroxymonosulfate (PMS) for Rhodamine B (RhB) degradation. Characterizations results demonstrated that the ZIF-67 nanocrystals are encapsulated within CNCs and subsequently arranged in a string-like configuration. In comparison to pristine ZIF-67, the ZIF-67@CNC catalyst presented superior performances for RhB dye removal both in terms of degradation efficiency and rate, as the kinetic rate constant increased 5.8-fold. This finding was attributed to the improvement in oxygen-containing groups and meso/microporous structures after the introduction of CNCs, leading to efficient binding to compounds and rapid molecular diffusion. Moreover, the ZIF-67@CNC exhibited remarkable stability throughout the catalysis process in aqueous solutions owing to the robust crosslinking between negatively charged CNCs and positively charged cobalt ions, which significantly mitigated the potential secondary pollution of cobalt to the environment. This research opens up new possibilities for the design of highly efficient and durable ZIF-67-based catalysts to promote future wastewater treatment technology.