Search Results (434)

Zeolitic imidazolate framework-8 (ZIF-8) is an important support for enzyme immobilization due to its good biocompatibility and structural tunability. However, the inherent structural characteristics of conventional ZIF-8 suffer from limited specific surface area, thereby restricting the achievable enzyme loading. In this study, we developed a novel alkali-induced (IA) strategy using sodium hydroxide to prepare IA-ZIF-8 with markedly enhanced textural properties. Subsequently, Pseudomonas fluorescens lipase (PFL) was successfully immobilized onto IA-ZIF-8 via physical adsorption, and the optimal conditions were systematically investigated. Compared with conventional ZIF-8, IA-ZIF-8 achieved a larger specific surface area (1462.3 m²/g), and a 9.8% increase in PFL loading. The resulting biocatalyst, IA-ZIF-8-PFL, exhibited significantly enhanced thermal and pH stability due to the confinement effect and protective microenvironment from the carrier. When the biocatalyst was applied to the chiral resolution of (R,S)-1-phenylethanol, it showed satisfactory catalytic activity and enantioselectivity with a conversion of 24.4% and an ee_s of 25.7%. In addition, IA-ZIF-8-PFL retained satisfactory reusability over five successive cycles. This work demonstrates that IA-ZIF-8 is a highly efficient carrier for immobilizing lipase and offers a green biocatalyst for the efficient preparation of chiral drug intermediates. Full article

Pork is highly perishable during storage, leading to enormous economic losses and potential food safety hazards. Anthocyanins (ANTs) possess excellent antioxidant and antibacterial activities, but their poor stability in practical applications limits their industrial application. To address these issues, a novel composite preservation film was prepared by the four-sided applicator solution casting method, using polylactic acid (PLA) and polybutylene adipate-co-terephthalate (PBAT) as matrix materials and ANTs@ZIF-8 as functional filler. Zeolitic imidazolate framework-8 (ZIF-8) encapsulated ANTs to enhance its stability and achieve sustained release, while the PLA/PBAT was selected for its good biodegradability, mechanical and barrier properties. The structure and properties of the PLA/PBAT/ANTs@ZIF-8 composite films were investigated, and the results showed that ANTs@ZIF-8 nanoparticles had stable dispersibility in the matrix, which effectively improved the compatibility between nanoparticles and the film matrix. The prepared composite films exhibited excellent tensile strength (TS), elongation at break (EAB) and water vapor transmission rate (WVTR), as well as good antibacterial activity against E. coli and S. aureus. Furthermore, the practical pork preservation performance of the films was investigated, and the results demonstrated that the composite films could effectively reduce the pH value, water loss, color difference, total volatile basic nitrogen (TVB-N) content and malondialdehyde (MDA) content of fresh pork during storage, successfully extending the shelf life of pork to 12 days. This study develops a multifunctional, biosafe, and biodegradable PLA/PBAT composite film incorporated with ANTs@ZIF-8, providing a feasible strategy and scientific reference for the design and development of high-performance active biodegradable packaging materials. Full article

Efficient removal of organic dye pollutants remains challenging owing to the limited adsorption capacity and poor reusability of most conventional adsorbents. Herein, rhombic-dodecahedral zeolitic imidazolate framework-67 (ZIF-67) was successfully fabricated via a facile aqueous strategy. The obtained ZIF-67 exhibited a high BET specific surface area of 1842.31 m² g⁻¹, with a maximum Langmuir adsorption capacity of 156.74 mg g⁻¹ toward methyl orange (MO). The adsorption kinetics successfully followed the pseudo-second-order model, and the material maintained 88.9% dye removal efficiency after six ethanol-regeneration cycles. Common inorganic anions (HCO₃⁻ and SO₄²⁻) presented a distinct inhibitory effect on MO adsorption. Static electrostatic potential calculations and hydrated molecular dynamics simulations were further adopted to reveal the interfacial adsorption behavior on typical ZIF-67 (100) and (110) facets. Based on equilibrated trajectories of 40–50 ps, both facet systems exhibited stable temperature and potential-energy fluctuations. The dominant Co–O(MO) radial distribution distances for (100) and (110) facets were determined to be 5.825 Å and 5.775 Å, respectively, both far beyond conventional short-range Co–O coordination lengths. The stronger radial ordering of the (110) facet suggests facet-sensitive interfacial organization, rather than direct Co–O chemical bonding during MO adsorption. Full article

Electrocatalytic water splitting offers a viable route to sustainable hydrogen generation, yet the development of non-noble metal catalysts that combine high efficiency with long-term stability remains a significant hurdle. Zeolitic imidazolate framework-67 (ZIF-67) has emerged as a potential electrocatalyst, but its activity is often limited by insufficient active sites and poor conductivity. In this study, Mn, Fe, and Ni doped derivatives of ZIF-67 (ZIF-67/M, M = Mn, Fe, Ni) were synthesized via a post-synthetic modification method to improve the electrocatalytic performance. The effects of metal doping on structure, morphology, and water splitting activity were systematically investigated. XRD and FTIR confirmed the successful incorporation of heteroatoms without destroying the crystalline framework, while TGA revealed altered thermal stability. BET measurements showed a transformation from microporous to mesoporous structures upon doping, and SEM exhibited crystal distortion, aggregation, and increased surface roughness. Electrochemical tests demonstrated that doping significantly enhanced both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances. At 10 mA cm⁻², ZIF-67/Fe exhibited the lowest overpotentials for OER (271 mV) and HER (338 mV), outperforming ZIF-67/Mn, ZIF-67/Ni, and pristine ZIF-67. Overall water splitting tests on ZIF-67/Fe showed negligible overpotential change after 24 h, confirming good ambient stability. In summary, metal doping effectively enhances the electrocatalytic water splitting performance of ZIF-67 by modulating its coordination environments and active site distribution, with ZIF-67/Fe exhibiting the best overall performance as a promising bifunctional electrocatalyst. Full article

Coupling renewable energy with seawater electrolysis is a highly promising strategy for sustainable hydrogen production. However, the practical application of direct seawater electrolysis remains challenging due to severe anode corrosion and the competitive chlorine evolution reaction (CER) induced by chloride ions. Herein, we report a facile cation-etching strategy to synthesise Fe@ZIF-67 catalysts at room temperature, using ZIF-67 as the sacrificial template and Fe²⁺ salts as the etching agent. The as-prepared Fe@ZIF-67 exhibits superior electrocatalytic activity for the oxygen evolution reaction (OER) in a simulated alkaline saline electrolyte (1.0 M KOH + 0.5 M NaCl). Specifically, it achieves a current density of 10 mA cm⁻² at a low overpotential of 259 mV, outperforming commercial RuO₂. Furthermore, an alkaline saline electrolyser assembled with Fe@ZIF-67 as the anode and Pt/C as the cathode requires a cell voltage of only 1.57 V to reach 10 mA cm⁻², which is significantly lower than that of the RuO₂||Pt/C benchmark (1.65 V). This work demonstrates that the cation-doping strategy effectively modulates the surface electronic structure of metal–organic frameworks (MOF)-based catalysts, providing a new perspective for optimising their performance in seawater electrolysis. Full article

The reverse water–gas shift (RWGS) reaction is a promising route for converting CO₂ into CO, an important feedstock for synthetic fuels and chemicals. In this study, Zn–Co zeolitic imidazolate frameworks (ZIFs), including ZIF-8, ZIF-67, ZIF-67-8, and the core–shell structures ZIF-8@67 and ZIF-67@8, were synthesized as catalyst precursors and thermally activated prior to catalytic testing. Transmission electron microscopy and elemental mapping confirmed the formation of well-defined core–shell architectures, while synchrotron X-ray diffraction verified the characteristic sodalite-type framework. Thermogravimetric analysis revealed substantial framework decomposition during activation at 700 °C. In situ time-resolved X-ray absorption spectroscopy (TR-XAS) showed that Zn remained predominantly in the Zn²⁺ state throughout heating, whereas Co²⁺ underwent progressive reduction to metallic Co⁰ at temperatures approaching 600 °C. Ex situ X-ray absorption spectroscopy confirmed the presence of Zn²⁺ species and metallic cobalt after activation. Catalytic testing of the activated ZIF-derived materials showed that Co-containing catalysts exhibited significantly higher RWGS activity than Zn-only ZIF-8-derived catalyst. Among the investigated samples, ZIF-67@8_C-500 achieved the highest performance, producing 2.50 μmol CO (equivalent to 50 μmol g⁻¹ catalyst) at 600 °C with a H₂/CO₂ ratio of 2:1. The strong dependence of activity on ZIF-67 core loading indicates that metallic cobalt generated from the Co-rich core plays a dominant role in CO₂ conversion. Thermal activation transformed the highly porous ZIF precursors into metallic Co-containing carbonaceous catalysts. The resulting structural evolution, rather than retention of the original porous MOF framework, governed the catalytic performance in the RWGS reaction. Full article

Due to its abundant active sites, the bimetallic zeolite imidazole framework ZnCo-ZIF-67 exhibits excellent catalytic performance on the key oxidant ammonium perchlorate in composite solid propellants. In addition, carbon fiber has been proven to promote the combustion of propellants due to its high thermal conductivity efficiency. In order to integrate the advantages of both, this study designed and prepared a novel composite catalyst, ZnCo-ZIF-67/CF, by a co-precipitation method. The thermal decomposition test demonstrated that the ZnCo-ZIF-67/CF composite exhibited significant catalytic activity. When the addition amount was 5 wt%, the high-temperature decomposition peak temperature of AP decreased significantly from 424.3 °C to 337.2 °C, and the combustion process was also significantly accelerated. Furthermore, analysis of the products of thermal decomposition gases revealed a significant increase in the proportion of N₂O in the catalyzed products to 55.7%, whilst the proportion of high oxidation state nitrogen-containing oxides such as NO₂ and NOCl decreased. This finding suggests that the highly dispersed metal active sites in ZnCo-ZIF-67/CF synergistically promote the decomposition reaction pathway of AP, leading to enhanced N₂O generation. This study proposes a novel approach for the development of efficient and stable AP decomposition catalysts, which has positive significance for the regulation of the combustion performance of propellants. Full article

Municipal wastewater is a major pathway for the continuous release of microplastics into aquatic environments, making the development of efficient and reusable capture materials essential for advanced water treatment. In this study, a multifunctional ZIF-67/g-C₃N₄/CS nanocomposite was designed by integrating cobalt-based zeolitic imidazolate framework ZIF-67 with graphitic carbon nitride (g-C₃N₄) and a chitosan (CS) biopolymer matrix. The novelty of this material lies in combining the high porosity and tunable surface chemistry of ZIF-67, the π-rich layered structure of g-C₃N₄, and the hydrophilic, amino-rich chitosan framework into a single adsorptive platform for simultaneous removal of chemically different microplastics. The nanocomposite achieved high removal efficiencies for polystyrene (PS), polypropylene (PP), and polyethylene (PE) microplastics with particle sizes of 20–25 μm, reaching 97.4%, 92.1%, and 90.3%, respectively, at pH 7.6 within 25 min. The higher affinity toward PS is attributed to additional π–π interactions between the aromatic PS chains and the conjugated domains of g-C₃N₄/ZIF-67, whereas PP and PE removal is mainly governed by hydrophobic adhesion, surface trapping, and interfacial interactions with the chitosan-supported porous framework. The equilibrium data were well described by both Langmuir and Freundlich models, with maximum adsorption capacities of 97.69, 94.86, and 93.67 mg g⁻¹ for PS, PP, and PE, respectively. The nanocomposite retained high recyclability, maintaining 95–97 ± 3.1% removal after five adsorption–desorption cycles. These findings demonstrate that ZIF-67/g-C₃N₄/CS is a durable and high-performance adsorbent for microplastic remediation, with strong potential for application in municipal wastewater treatment, constructed wetlands, and advanced water-polishing systems. Full article

Information security and anti-counterfeiting are crucial across various industries. To address the limitations of traditional anti-counterfeiting materials, including low responsiveness, easy replication, and poor environmental stability, a fluorescein (Flu) loaded zeolitic imidazolate framework (ZIF-8) photothermal-responsive anti-counterfeiting hydrogel was designed. Flu was first confined within ZIF-8 via a one-pot method and then embedded into a polyacrylamide/lauryl methacrylate (PAM/LMA) network. This hydrogel emits intense green luminescence under 365 nm UV illumination. Its fluorescence can be quenched by Fe³⁺ and recovered upon exposure to PO₄³⁻, which endows the material with rewritable data storage capacity. Sodium dodecyl sulfate (SDS) and sodium chloride (NaCl) in the hydrogel provide a temperature-dependent reversible transparency transition, allowing multi-level information encryption through the synergistic action of temperature, ions, and UV light. In addition, the hydrogel also features low toxicity, degradability, and an environmentally friendly solvent-free synthesis. This work demonstrates a multi-stimuli responsive strategy that overcomes the limitation of traditional single-responsive anti-counterfeiting materials, offering a promising approach for the design of rewritable and eco-friendly intelligent anti-counterfeiting systems and serving as a reference for the development of multifunctional responsive materials. Full article

In this study, response surface methodology (RSM) was employed to evaluate and optimize the key parameters for the solvothermal synthesis of Zeolitic Imidazolate Framework-8 (ZIF-8) nanoparticles, including solvent type, reaction temperature, reaction time, and material ratio. A multivariate regression model identified the optimal preparation conditions as ethanol as the solvent, a reaction temperature of 120 °C, a reaction time of 4 h, and a 5:1 molar ratio of 2-methylimidazole to zinc acetate. The resulting ZIF-8 nanoparticles exhibited highly selective adsorption capacity toward anthraquinones and were successfully applied to the rapid extraction and detection of five anthraquinones from Cassiae semen. By investigating the adsorbent dosage, adsorption efficiency, elution solvent, and elution efficiency, we established the optimal experimental conditions. Briefly, 20 mg of ZIF-8 nanoparticles were added to 10 mL of Cassia semen extract, and the mixture was shaken for 10 min before centrifugation. The residual anthraquinones in the supernatant were quantified by Ultra Performance Liquid Chromatography (UPLC). The adsorption efficiencies of aloe-emodin, rhein, emodin, chrysophanol, and physcion were 80.2%, 93.8%, 100%, 100%, and 100%, respectively. When eluted with methanol/100 mM NaHCO₃ solution (1:1, v/v), the corresponding elution efficiencies of these compounds were 82.8%, 97.8%, 85.1%, 93.2%, and 65.3%, respectively. The relative standard deviations (RSDs) for method precision, stability, and repeatability were all below 4.0%. The prepared ZIF-8 nanoparticles showed favorable adsorption performance toward the five anthraquinone components. The method is simple to operate, requires minimal sample and solvent consumption, and can be used for rapid extraction and detection of anthraquinones in traditional Chinese medicinal materials such as Cassiae semen. This work provides a scientific reference for the application of MOFs nanomaterials in food safety inspection and quality control of traditional Chinese medicinal materials. Full article

Background: Conventional and refractory wounds frequently remain in a prolonged inflammatory phase associated with excessive reactive oxygen species (ROS) accumulation and disruption of endogenous electrical cues. Methods: A multifunctional nanocomposite hydrogel was fabricated via an amidation condensation reaction, utilizing 3-amino-4-methoxybenzoic acid (AMB)-modified carboxymethyl chitosan (PAMB-CMCS) and decellularized extracellular matrix (dECM) as macromolecular networks, integrated with Astragaloside IV-Loaded Polydopamine/Zeolitic Imidazolate Framework-8 (AS@PDA/ZIF-8) nanoparticles. Results: The hydrogel provided a biomechanically supportive scaffold with compressive strength of 27.24 ± 1.9 kPa and breaking strength of 28.2 ± 2.8 kPa and exhibited electrical conductivity of 29.84 mS/cm, ROS-scavenging activity, and near-infrared (NIR)-responsive photothermal behavior reaching 62.55 °C. The integrated PDA@ZIF-8 nanoplatform further contributed to antibacterial performance and localized AS release, thereby improving the wound microenvironment and accelerating full-thickness cutaneous defect repair. Conclusions: This macromolecule-based composite hydrogel offers a promising therapeutic strategy for complex wound management. Full article

Meltable metal–organic frameworks (MOF) are essential for the formation of MOF glasses, which have emerged as a new family of functional materials offering promising potential for applications in gas separation, luminescence, energy storage, and beyond. Herein, the synthesis of iron-based zeolitic imidazolate framework (ZIF) crystals, specifically Fe₃(Im)₆(HIm)₂, where Im is imidazolate, is reported. Upon the substitution of some Im linkers with a secondary ligand, 5,6-dimethylbenzimidazole (dmbIm), it was found that such substitution induces the formation of new phases: one phase exhibits meltability and subsequent glass formation, while another phase [Fe₃(Im)_1.56(dmbIm)_4.44(HIm)₂] is non-meltable. Through structural characterizations, the configuration of the tetrahedral [Fe-linkers] units was revealed to be crucial in determining the meltability of Fe-ZIF. The incorporation of a large secondary ligand hinders the occurrence of melting. This work provides an insight into how ligands affect the accessibility of the liquid state of MOFs, showing a practical strategy for designing meltable MOFs. Full article

Currently, single-modal tumor therapy has significant limitations, while multi-modal combination therapy can overcome this bottleneck and open up new pathways for enhancing the efficacy of tumor therapy. However, it is still difficult to design a functionalized nanocarrier that can simultaneously mediate multiple therapeutic approaches. To tackle this challenge, we developed a multifunctional nano-codelivery system with glucose oxidase (GOx) loaded inside iron-doped zeolitic imidazolate framework-8 (Fe/ZIF-8), abbreviated as GFZ. This system effectively integrates the synergy and complementarity between ferroptosis therapy and starvation therapy (STT). Herein, GFZ innovatively combines the pH sensitivity of the ZIF-8 skeleton with the EPR effect of nanoparticles to achieve on-demand triggered release, significantly improving the accuracy of tumor targeting. Furthermore, GOx-mediated STT effectively alleviates the insufficiency of endogenous H₂O₂ during the ferroptosis process, thereby enhancing and synergizing with ferroptosis therapy. Experiments demonstrated both in vitro and in vivo that GFZ activates antitumor cascade reactions, inhibits tumor recurrence and metastasis, and exhibits excellent biocompatibility. Consequently, given its remarkable potential, GFZ is poised to emerge as a new mode of nano-delivery platform. Full article

Manganese-based cathodes offer high capacity, low cost, and safety for aqueous zinc-ion batteries (AZIBs), yet suffer from Mn dissolution, Jahn–Teller distortion, and sluggish Zn²⁺ kinetics. Herein, a Zn/Co co-doped MnO nanoporous carbon composite (denoted as ZnCo-MnO@NPC) derived from a bimetallic ZnCoMn metal–organic framework (ZnCoMn-MOF-74) is successfully synthesized and proposed as a high-performance cathode to address these challenges. The introduction of Zn²⁺ increases the initial specific capacity of MnO, while Co doping effectively suppresses the Jahn–Teller distortion and improves the integrity of the structure. Furthermore, the nanoporous carbon matrix facilitates electrolyte infiltration and accelerates ionic transport. To further suppress dendrite growth and enhance cycling stability, a zeolitic imidazolate framework (ZIF-8) protective layer is engineered on the zinc anode (denoted as ZIF-8@Zn), effectively mitigating dendrite formation. The ZnCo-MnO@NPC//ZIF-8@Zn full cell demonstrates superior electrochemical performance, delivering 281.3 mAh g⁻¹ at 0.1 A g⁻¹ and retaining 98.7% of this value after 3500 long-term cycles at 2.0 A g⁻¹, a remarkable finding that underscores its potential for high-performance energy storage. Collectively, this work highlights that transition metal ion doping represents an effective way to design efficient high-performance MOF-derived cathodes of AZIBs. Full article

Dopamine is a key neurotransmitter and neuromodulator that regulates many critical brain functions. Accurate monitoring of its level is essential for neuroscience as well as the diagnosis and treatment of many brain diseases. In this work, we developed a new electrochemical sensor, comprising phosphorus-doped graphitic carbon nitride (P-g-C₃N₄) and zeolitic imidazolate framework 67 (ZIF-67), for dopamine detection. In this composite electrode material, ZIF-67 provides numerous adsorption and sensing sites, while P-g-C₃N₄ enhances overall electrical conductivity and stability. Cyclic voltammetry tests reveal the redox behavior of dopamine at the surface of the composite electrode across various pH values and scan rates. Using differential pulse voltammetry, the sensitivity and selectivity of this dopamine sensor were assessed, identifying a limit of detection of 0.39 nM. Further successful quantification of dopamine in urine samples suggests the potential practical use of this new composite electrochemical sensor for detecting dopamine and/or other neurotransmitters. Full article