Zeolitic Imidazolate Framework Research Articles

Pt3(CoNi) Ternary Intermetallic Nanoparticles Immobilized on N-Doped Carbon Derived from Zeolitic Imidazolate Frameworks for Oxygen Reduction.

Pt-based intermetallic compound (IMC) nanoparticles have been considered the most promising catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). Herein, we propose a strategy for producing ordered Pt3(CoNi) ternary IMC nanoparticles supported on N-doped carbon materials. Particularly, the Co and Ni are originally embedded into ZIF-derived carbon, which diffuse into Pt nanocrystals to form Pt3(CoNi) nanoparticles. Moreover, a thin layer of carbon develops outside of Pt3(CoNi) nanoparticles during the cooling process, which contributes to stabilizing the Pt3(CoNi) on carbon supports. The optimal Pt3(CoNi) nanoparticle catalyst has achieved significantly enhanced activity and stability, exhibiting a half-wave potential of 0.885 V vs reversible hydrogen electrode (RHE) and losing only 16 mV after 10,000 potential cycles between 0.6 and 1.0 V. Unlike the direct-use commercial carbon (VXC-72) for depositing Pt, we utilized ZIF-derived carbon containing dispersed Co and Ni nanocluster or nanoparticles to prepare ordered Pt3(CoNi) intermetallic catalysts.

A pH-modulated polymeric drug-release system simultaneously combats biofilms and planktonic bacteria to eliminate bacterial biofilm

Bacterial infection, leading to biofilm formation, raises grave concerns. With the aim of eliminating both integrity of biofilms and individual bacterial cells, it is desirable to develop bacterial biofilm-eliminating material to be combined with dispersal and anti-microbial agents. Herein, a biofilm-eliminating enzyme (α amylase) was incorporated in novel pH-sensitive polymer hydrogel, Poly (methacrylic acid-co-2-(dimethylamino)ethyl methacrylate), which encapsulates drug-loaded porous Zeolitic Imidazolate Framework-8 (ZIF-8). At body temperature (37 °C) the maximum swelling of the hydrogel was observed at pH 8.5, which assisted in rupturing biofilm by releasing α amylase. Amylase, encapsulated in polymer matrix reached 90% release after 6 days at 8.5, while CIP was released 96% on day 23 at pH 8.5. The antibiofilm activity of drug-releasing system was assessed against E. coli and S. aureus. The overall bacterial viability of biofilms showed significant time-dependent declines, when exposed to drug-loaded hydrogel. Importantly, cytotoxicity experiments showed excellent biocompatibility of hydrogel. In the in vivo deep wound infection model, drug-loaded hydrogel treatment showed complete wound closure with proper tissue regeneration. No inflammatory, or systemic toxicity of hydrogel was observed. The drug release from hydrogel is initiated only upon receiving physiological cue arising due to biofilm formation. Therefore, this hydrogel serves as reservoir for antibacterial drug, which release it only in presence of biofilm and thus work for sustained release for long period, compared to conventional drug loaded films or coatings. A powerful modality for management of biofilm-associated infections can be provided by the proposed synergistic strategy for complete elimination of biofilms.

Temperature dependent electrocatalytic activity of molybdenum-based ZIF-67 nanorods for water splitting

Several strategies have been adopted to enhance the electrochemical features of metal-organic framework structures for water splitting, however, a suitable conditions can effectively boost the electrocatalytic activity. Herein, molybdenum-based zeolite imidazolate frameworks (Mo2gZIF-67 and Mo4gZIF-67) have been synthesized by solvothermal process and electrocatalytic activity was examined at various elevating temperatures of 1 M KOH electrolyte. Mo4gZIF-67 nanorods showed the overpotential (η10) of 358 mV at 20 °C, which was improved to 221 mV at 80 °C for the oxygen evolution reaction. Mo4gZIF-67 nanorods exhibited the Tafel slope of 77 mV dec−1 at 80 °C and followed the Volmer-Heyrovsky mechanism. LSV curves reveal that Mo4gZIF-67 nanorods showed a greater current density and a good turnover frequency (TOF) of 221.0 ms−1 at the fixed VRHE of 0.7 V. Similarly, Mo4gZIF-67 nanorods revealed the η10 of 181 and 93 mV at 20 and 80 °C, respectively for the HER process. Mo4gZIF-67 nanorods displayed a Tafel slope of 95 mV dec−1 and TOF of 213.50 ms−1. The enhanced electrocatalytic activity may be due to rising temperatures, enhanced electrical conductivity at rising temperatures, well defined nanorods shape and greater ECSA, which provided the active sites and facile the flow of charge carriers for oxygen and hydrogen evolution reaction. The electrocatalyst, Mo4gZIF-67 nanorods exhibited a uniform current density during stability tests for 30 h at 20 °C, which was increased at 80 °C. Temperature elevation remarkably enhanced the HER and OER characteristics of the Mo4gZIF-67 nanorods and suggested an effective electrocatalyst for water splitting.

Template-synthesizing hollow cubic CeO2/Co3O4 heterostructure as electrocatalysts for sensing hydrogen peroxide

H2O2 as an important intermediary is becoming more widely acknowledged, and interest in its detection has increased significantly. Herein, we developed a hollow cubic CeO2/Co3O4 heterostructure and further employed as non-enzymatic H2O2 detection sensor through a series of facile synthesis strategies using cobalt-based zeolitic imidazolate framework as a template. The synthesized CeO2/Co3O4 with huge cavity structure offers numerous electrocatalytic active sites for the target analyte, thus endowing its high sensitivity (60.5 μA. mM−1cm−2), excellent selectivity, broad detection range for H2O2 (10 μM -1 mM), and favorable working potential (-0.45 V). Not only that the CeO2/Co3O4 sensor achieved satisfactory recovery and accuracy in real lake-water samples.

Near-infrared light enhanced oxygen vacancies on metal organic frameworks through photothermal effect for peroxydisulfate activation to remove organic pollutants

Peroxydisulfate (PDS)-based advanced oxidation processes (AOPs) are a promising strategy for addressing the challenges of contamination in aqueous environment. Taking advantage of solar energy based photocatalysis showed great potential on PDS activation for pollution control. However, the limited usage of near-infrared (NIR) region by photocatalysts restricted the realization of using full sunlight energy. Herein, zeolitic imidazolate frameworks derived materials (ZNC) with oxygen vacancies (VO) are designed and obtained, which can efficiently activate PDS under NIR light due to the photothermal effect, exhibiting superior carbamazepine (CBZ) degradation performance (84 % of CBZ within 60 min). Further quenching tests and electron paramagnetic resonance detection demonstrate that the photothermal effect can enhance the concentration of oxygen vacancies on the surface and facilitate charge separation of ZNC, which effectively activate PDS to generate O2−, 1O2, and h+, thus significantly enhancing the photocatalytic degradation of CBZ. Additionally, combining the results of intermediates analysis and DFT calculation, a systematic CBZ degradation pathway by two tracks is proposed. Moreover, the overall potential risks of CBZ are expected to be weakened in the ZNC/PDS/NIR process through photothermal catalytic degradation. Thus, a new strategy is provided for optimizing the use of solar energy to boost PDS activation for water purification.

MOF-on-MOF-derived double-shelled iron-doped cobalt sulfide nanosheet arrays modified by CeO2 for asymmetric supercapacitors

Through deliberate design of nanostructures and modifications to the surface, significant advancements in energy storage performance can be achieved. This work focuses on the creation of iron-doped cobalt sulfide hollow nanosheets, featuring a distinctive double-shelled structure. This unique architecture is achieved by replacing the ligand within zeolitic imidazole framework (ZIF)-L with K4Fe (CN)6, followed by a sulfurization process. Subsequently, a layer of CeO2 cladding is integrated using solvothermal synthesis. The resulting hollow double-shelled structure fosters intimate contact between the electrode material and electrolyte, effectively mitigating the challenges associated with substantial volume fluctuations during electrochemical processes. Additionally, the porous characteristics inherited from ZIF, augmented redox reactions resulting from elemental doping, and coordination with the external CeO2 modification further enhance the electrochemical performance of the electrode. Consequently, the Fe-CoS/CeO2 electrode exhibits an impressive specific capacitance of 3727.5 F g−1 at 1 A g−1. When employed in an asymmetric supercapacitor configuration with activated carbon (AC) serving as the negative electrode, the Fe-CoS/CeO2//AC demonstrates exceptional energy storage capabilities, achieving 36.4 W h kg−1 at 800.0 W kg−1 and exhibiting superior long-term stability with 89.8 % retention of initial capacitance after 10,000 cycles at 10 A g−1.

Dispersive solid-phase extraction using ZIF-8 coupled to high performance liquid chromatography–tandem mass spectrometry for the detection of 80 pesticides in poultry egg and their products

AbstractPeople are consuming increasing amounts of poultry eggs and their products, and their safety is always a public concern. However, the complex composition of poultry eggs and their products, particularly the proteins and lipids, can easily cause matrix effects, requiring the use of sorbents to remove these components to avoid affecting the detection results. Zeolitic imidazolate framework-8 (ZIF-8) is a MOF material with high specific surface area, high porosity, and high stability, making it widely used as a sorbent in pesticide residue detection. In this study, we evaluated the performance of ZIF-8 compared to classic solid phase extraction (SPE) and Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) in the pretreatment step. The results showed that ZIF-8 could better reduce the matrix effect in poultry eggs and their products. After optimizing the extraction solvents, chromatographic and mass spectrometric conditions, and pretreatment processes, we established a method using ZIF-8 as a sorbent combined with high performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) for the detection of 80 pesticide residues in seven different types of poultry eggs and their products, yielding satisfactory results. All the target analytes showed good linearity, both with values of r2 > 0.996. The average recovery and coefficients of variation (CVs), expressed as relative standard deviations, ranges from 72.5% to 113.2% (chicken egg) (CV: 0.1%–12.9%), 72.2%–114.2% (salted duck egg) (CV: 0.1%–9.8%), 70.3%–105.6% (goose egg) (CV: 0.1%–12.0%), 70.9–120.4% (marinated egg) (RSD: 0.1%–14.8%), 70.7%–108.5% (duck egg) (CV: 0.1%–12.3%), 71.1%–105.0% (quail egg) (CV: 0.2%–5.6%), 70.7%–111.5% (century egg) (CV: 0.1%–13.4%). The values of limit of detection (LOD) and limit of quantification (LOQ) were, respectively, ranging from 0.15 to 0.85 μg kg−1 and 0.34–2.6 μg kg−1. When this method was applied to the detection of real samples, one chicken egg sample was found to contain 0.013 mg kg−1 of fipronil, and one marinated egg sample was found to contain 0.0087 mg kg−1 of thiamethoxam, indicating the necessity of stringent safety monitoring for poultry eggs and their products.

Au-modified metal-organic framework photonic heterostructure as a SERS sensor for enrichment and detection of trace organic dyes and pesticides

Surface enhanced Raman scattering (SERS) sensors with excellent sensitivity, stability and repeatability are essential for the ultrasensitive analysis of trace targets. In this study, a SERS sensor was developed using a photonic heterostructure composed of Au nanoparticles (AuNPs) & Zeolitic Imidazolate Framework-8 photonic crystals (ZIF-8 PCs). The sensor aims to enrich and detect organic dyes and pesticides, with enhanced detection capabilities achieved through adjustments in AuNPs content and the band-edge effects of ZIF-8 PCs. The sensor exhibited excellent performances in detecting 4-mercaptobenzoic acid. The detection limit was 1 × 10–12 mol·L−1, with a relative standard deviation of 5.0 % and the enhancement factor of 1.439 × 1011. Furthermore, the self-enrichment function of the sensor was verified through molecular dynamics simulations. This validation enabled the SERS sensor to be effectively utilized for the analysis of Rhodamine 6 G (R6G), methylene blue (MB), Thiabendazole (TBZ) and Parathion-methyl (PTM) without complex pretreatment. The detection limits achieved were 1 × 10–12 for R6G and MB, and 1 × 10–11 mol·L−1 for TBZ and PTM, respectively. This study presented an effective strategy for constructing high-performance SERS sensors, elucidated the mechanism of analyte enrichment and achieved the detection of samples in natural lake water, which offers a new option for on-site monitoring of contaminants with a portable Raman spectroscopy.

Synchronously Repairing Core/Surface Defects of Carbon Fibers by In Situ Growth of ZIF-8 and Uniquely Matched High-Energy Irradiation.

Currently, the actual mechanical properties of carbon fibers (CF) differ significantly from the theoretical values. This is primarily attributed to significant limitations imposed by structural defects, greatly hindering the widespread application of CF. To solve this problem, we used in situ growth of zeolitic imidazolate framework-8 (ZIF-8) and γ rays to modulate the core-shell of CF in this study. For the surface structure of CF during the process of γ irradiation, the organic structure within ZIF-8 gradually degrades and forms a cross-linking structure with the surface defects of the CF. This process significantly enhances the binding strength between inorganic material from the postdecomposition of ZIF-8 and the carbon layer on the surface of CF, repairing the surface defects. For the internal structure of CF, γ irradiation can improve the orientation of the internal micropores of CF and increase the degree of internal graphitization of CF. In this paper, an in-depth analysis of CF before and after repair was conducted by using characterization techniques such as nanoindentation and ultrasmall angle X-ray scattering (USAXS). Compared to unmodified CF, its mechanical properties improved by approximately 19.99%, which exceeds that in approximately 95% of similar works in the field.

Fluorescence-enhanced MOF-encapsulated AuNCs for highly sensitive detection of melanin

Melanin is an important marker of human disease and aging. It is necessary to quickly and sensitively detect melanin. In this study, a novel fluorescence strategy for the rapid and sensitive detection of melanin was established based on a nanocomposite (AuNCs@ZIF-8) consisting of gold nanoclusters (AuNCs) and a zeolite-imidazole framework (ZIF-8). The confined space of ZIF-8 restricted the rotation and vibration of the AuNCs, reducing their free movement. Thus, the non-radiative transition energy of the AuNCs decreased, leading to stronger fluorescence intensity of AuNCs@ZIF-8. Melanin acted as an electron acceptor while AuNCs@ZIF-8 acted as an electron donor. Through electron transfer, the fluorescence of the AuNCs@ZIF-8 was effectively quenched. Compared to the AuNCs, AuNCs@ZIF-8 showed a more significant quenching effect. Therefore, using the fluorescence value of AuNCs@ZIF-8 as the reporting part, the melanin level could be detected by the fluorescence quenching in 24 min. The range of linearity of the approach was 0.1–500.0 μg⋅mL−1, and the detection limit of melanin is 0.03 μg⋅mL−1.

Carbonized porous zeolitic imidazolate framework as promising electrode for electrochemical supercapacitors

In order to manufacture effective supercapacitors with improved electrochemical performance, it is imperative to investigate greater surface area electrode materials. This work describes the development of a cost-effective method for the carbonization of porous zeolitic imidazole framework (ZIF8) to utilize as electrode of electrochemical supercapacitors. The electrode materials were prepared by synthesizing highly porous ZIF8-P followed by pyrolysis at 500 °C (ZIF8-P-500). The pyrolysis of ZIF-8 significantly strengthened the porous behavior by maintaining their hexagonal particles and obtaining high surface to volume ratio. The measurements using constant current charge/discharge (GCD) and cyclic voltammetry (CV) were used to evaluate the electrochemical capacitance characteristics of the synthesized ZIF8-P based electrode. The supercapacitor assembly using the optimized ZIF8-P electrode exhibited a high specific capacitance of ∼423.9 Fg–1 with exceptional cycle stability by maintaining capacitance of ∼86.7 % from its initial capacitance after 5000 cycles. Thus, the results indicate that the ZIF8-P based supercapacitor offers a compelling path for creating porous carbon electrodes from MOFs using low cost pyrolysis for advancing supercapacitor technology.

Long cycle life Zn-I2 batteries: Utilizing Co/N Co-doped carbon matrix derived from zeolitic imidazolate framework-67 as a bifunctional iodine host

Zinc-iodine batteries (ZIBs) emerge as a clean energy transfer device with very excellent application prospects due to its abundant natural reserves, environmental friendliness, low cost, and good safety. However, the severe shuttle effect of soluble polyiodide in aqueous medium and the sluggish reaction kinetics of iodine substances restrict the application potential of ZIBs. Herein, we report a promising iodine host material for ZIBs by deriving from zeolite imidazole framework-67 (ZIF-67) with co-doping of cobalt and nitrogen. The synergistic effect of porous carbon and cobalt and nitrogen co-doping is revealed by employing in-situ Raman spectroscopy and UV–vis absorption spectroscopy. It is found that the outstanding electrochemical behavior could be attributed to the efficient adsorption for polyiodide and catalyzing the conversion reaction between iodine substances, inhibiting the shuttle effect of polyiodide, and ensuring cycling stability. Consequently, the resultant ZIBs possess a high specific capacity of 152.4 mAh g−1 at rate of 5 C (1 C = 211 mA g−1), and long cycle stability of 24,000 cycles with more than 80 % capacity retention. This work provides a feasible and efficient strategy to realize high-performance ZIBs.

Tuning the local electronic structure of Co15V-ZIF through bimetallic synergies as a bifunctional electrocatalyst for overall water splitting

Co-based bimetallic zeolite imidazolate frameworks (ZIFs) have been shown as promising electrocatalysts for the oxygen evolution reaction, but their electronic structure’s influence on the catalytic performance for overall water splitting still needs further investigation. In this study, Co15V-ZIF, structured as two-dimensional (2D) nanosheet arrays, are grown on nickel foam using one-step co-precipitation strategy. Owing to the synergistic effects of vanadium (V) and cobalt (Co) reasonably regulating the electronic structure, the synthesized bimetallic ZIFs demonstrate superior catalytic performance, which required the overpotentials of only 227 and 68 mV to achieve a current density of 10 mA cm−2 in 1 M KOH for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Furthermore, the water electrolyzer assembled with bimetallic ZIF as cathode and anode exhibits the capability to achieve 10 mA cm−2 at a low cell voltage of 1.57 V. In situ Raman spectroscopy reveals that the introduction of V facilitates the formation of V-CoOOH, the real active site for OER, at lower applied potentials. Besides, it induces a local acidic environment on V-Co(OH)2, the real active sites, thereby enhancing the HER performance of the sample. Density Functional Theory (DFT) calculations further show that the synergistic effects of V and Co induce electron redistribution, thereby improving electrical conductivity, reducing the energy barrier for water dissociation and hydrogen adsorption, which promotes the formation of H3O+ and triggering H3O+-induced water reduction in alkaline media. This work provides new insight into tailoring electronic structures to rationally design highly efficient ZIF electrocatalysts.

Ruthenium-doped dual-phase cobalt catalysts for enhanced electrocatalytic hydrogen evolution

Controlling the structural sensitivity and selectivity of metal catalysts in reactions, such as the hydrogen evolution reaction (HER) on cobalt crystals, remains a challenging issue in heterogeneous catalysis. In this study, we introduced a straightforward approach to tuning the phase composition of hexagonal close-packed cobalt (HCP-Co) and face-centered cubic cobalt (FCC-Co) in a core–shell Co/C catalyst through the incorporation of Ru atoms. The HER performance was evaluated by controlling the contents of HCP-Co and FCC-Co phases in the catalysts. Single-atom Ru-doped cobalt catalysts containing dual-phase HCP and FCC were prepared by a mechanical ball-milling zeolitic imidazolate framework (ZIF-67) with appropriate ruthenium chloride, followed by a pyrolysis process. The doping of Ru resulted in changes in the contents of the HCP-Co and FCC-Co phases, which significantly boosted the HER activity of the catalysts. The obtained biphasic Ru-Co/C catalyst demonstrated ultra-low HER overpotential and promising stability in alkaline and acidic media, outperforming single-phase cobalt and commercial Pt/C catalysts. Theoretical calculations revealed the synergistic catalysis effect of biphasic cobalt on HER. These findings, which indicated that significant activity dependence on the crystallographic structure, may inspire new design concepts for efficient metal electrocatalysts.

Hybrid effects of graphene oxide-zeolitic imidazolate framework-67 (GO@ZIF-67) nanocomposite on mechanical, thermal, and microstructure properties of cement mortar

The addition of two-dimensional nanomaterials, such as graphene oxide (GO), and three-dimensional nanomaterials, such as zeolitic imidazolate framework-67 (ZIF-67), has shown great promise in improving the characteristics of cement-based systems. Consequently, a thorough understanding of the synergistic interactions between 2D and 3D nanomaterials in cement-based mortars is necessary. However, there is a lack of research on the use of graphene oxide-zeolitic imidazolate framework-67 (GO@ZIF-67) nanocomposites. Accordingly, this study investigated the hybrid effects of GO@ZIF-67 nanocomposites on the mechanical strength, hydration kinetics, shrinkage performance, and microstructural features of cement mortars. The GO@ZIF-67 nanocomposite was synthesized and added to the cement mortar at various concentrations (0.3, 0.4, and 0.5 wt %). The developed nanocomposite cement mortar was characterized using SEM-EDS, XRD, and DSC-TGA. The results indicated that the hybrid GO@ZIF-67 slightly improved the compressive strength of the cement paste, with a synergistic effect observed at specific concentrations. However, microstructural analysis revealed that the presence of hybrid nanomaterials did not facilitate the assembly and regulation of hydration crystal growth, nor did it significantly impede growth, resulting in minimal effects on the properties of cement mortar. Additionally, the nanocomposite influenced the hydration reactions and the formation of specific hydration products, introduced defects, and weakened the microstructure of the cement mortar. Moreover, an increase in the hybrid nanocomposite content led to higher drying shrinkage and water absorption, indicating a reduced durability of the cement mortar. Further research is required to optimize the use of GO@ZIF-67 nanocomposites in cement mortars to achieve the desired balance of properties.

Structural Comparisons, Fluorescence Properties, and Glass-to-Crystal Transformations of Heat-Cooled and Melt-Quenched Zeolitic Imidazolate Framework Glass.

As a representative of zeolitic imidazolate framework glass, agZIF-62 has been reported to be synthesized using a melt-quenching method in which the ZIF-62 crystal is heated to a temperature above the melting point. Interestingly, we unexpectedly found that agZIF-62 can also be synthesized by simple heating at temperatures lower than the melting point, which may be assisted by the release of encapsulated solvent molecules. The structural differences between melt-quenched agZIF-62 (MQ-agZIF-62) and heat-cooled agZIF-62 (HC-agZIF-62) were investigated. The results indicated that MQ-agZIF-62 is closer to the liquid state, while HC-agZIF-62 is closer to the crystal state. Interestingly, their luminescent emissions exhibit significant differences. Compared with the ZIF-62 crystal, MQ-agZIF-62 showed a blue-shift of 14 nm, whereas HC-agZIF-62 showed a red-shift of 9 nm. The emission intensity of agZIF-62 is also significantly stronger than that of ZIF-62; thus, rapid semiquantitative detection of the content of the MOF glass in glass and crystal mixtures can be achieved. In addition, HC-agZIF-62 and MQ-agZIF-62 can transform into ZIF-62 crystals via a solvent-media mechanism. This study provides new insights into ZIF-62 glass.

Metal-organic framework derived cobalt and iron oxide nanosheets for ppb-concentration and highly selective hydrogen sulfide sensing

Hydrogen sulfide (H2S) sensing with ppb concentration detection limit and high selectivity is highly desired in future exhaled diagnoses of halitosis, asthma and down syndrome, however, needs further developing. Here, a ppb-concentration and highly selective H2S sensing has been developed with the two-dimensional cobalt and iron oxide nanosheets (CoFexOy NSTs), which is transformed from leaf-shaped zeolitic imidazolate frameworks {ZIF-L(Co)} by combined Fe2+ ion-etching and annealing. Typically, as-prepared CoFexOy NSTs are of ∼ 10 nm thick with rough surface. Beneficially, the CoFexOy NSTs present outstanding selectivity to H2S against other interfering gases and exhibit a detection limit as low as 50 ppb. Remarkably, the sensor prototypes exhibit high response to 10 ppm H2S (Ra/Rg = 23.8) and fast response speed (∼13 s to 10 ppm H2S). Theoretically, such excellent H2S sensing might be attributed to the high surface ratio of CoFexOy NSTs providing enriched adsorption sites for H2S molecules. Practically, a H2S sensing device built with the CoFexOy NSTs sensor prototype is simulated for detecting H2S with reliable response, which is potential in future intelligent healthcare.

“Synergistic anticoagulant and endothelial regeneration strategy” based on mussel-inspired phospholipid copolymer coating and bioactive zeolitic imidazolate frameworks-90 to maintain the patency of CoCr stent

Given the risks of poor patient compliance and bleeding associated with current dual antiplatelet therapies, it is urgent to develop the next generation of cardiovascular stents with anticoagulation and rapid endothelialization capabilities. Inspired by the prominent bioactivity and bioavailability of zeolitic imidazolate framework-90 (ZIF-90) in driving endothelial cell (EC) morphogenesis, this research proposes a “synergistic anticoagulant and endothelial regeneration strategy” depending on mussel-inspired phospholipid copolymer (MIPC) and ZIF-90. Depending on the copolymerization of the catechol with dopamine (Dopa) monomers, Dopa/MIPC coating was immobilized on the surface of CoCr via a one-pot process for resisting the initial thrombosis induced by platelets and fibrinogen. Meanwhile, ZIF-90 was loaded on the coating via coordination effect, aiming to accelerate the proliferation and migration of ECs. Compared with CoCr, the well-designed CoCr-Dopa/MIPC@ZIF-90 not only reduced fibrinogen adhesion by approximately 40 % and platelet adhesion by almost 55 %, but also promoted the proliferation and migration of ECs significantly in vitro. Furthermore, the blood flow velocity of CoCr-Dopa/MIPC@ZIF-90 stent was similar to natural aorta and ECs coverage on it was greatly strengthened after 30 days in a rat aorta vascular stent implantation model. Collectively, CoCr-Dopa/MIPC@ZIF-90 exhibited obvious superiority in reducing the formation of thrombus and promoting endothelial regeneration, which might meet the high requirement for the next generation of vascular stent.

The preparation of ammonium polyphosphate@ nickel/cobalt-layered double hydroxide and its application as flame retardant in thermoplastic polyurethane

Inspired by the significant synergistic effect of transition metals and ammonium polyphosphate (APP) on flame reatrdancy, a nickel/cobalt-layered double hydroxide derived from a selected zeolitic imidazolate framework-67 (APP@NiCo) was constructed onto the surface of APP to enhance the fire safety of thermoplastic polyurethane (TPU). The results demonstrated that TPU containing 6 wt% APP@NiCo exhibited a LOI value of 27.7 % and achieved UL-94 V-0 rating. Furthermore, there was a significant reduction in the peak heat release rate, heat release rate, and total smoke production by 72.8 %, 37.5 % and 56.9 %, respectively. The remarkable improvement in flame retardancy was contributed to the highly synergistic charring catalysis of APP and dual transition metals cobalt and nickel, which effectively promoted the formation of robust char layers during TPU combustion for enhancing fire safety.

Dual-continuous microneedle patch integrating transdermal delivery of pH-sensitive licorzinc MOFs and Zn2+ hydrogel sensors for treating alopecia areata

Licorzinc is a commonly used immunomodulator, but faces poor water solubility, high oral dose, and side effects of zinc accumulation by long-term administration. Herein, a new licorzincform was developed by adsorbing glycyrrhizic acid (GA) into zeolitic imidazolate framework-8 (GA@ZIF-8) with superior solubility and acid-responsive drug release properties. Then, a dual-continuous microneedle patch was developed for simultaneous transdermal delivery of GA@ZIF-8 and monitoring Zn2+ in local tissues, where dissolving microneedles as a drug delivery unit were fabricated from hyaluronic acid. In contrast, swollen hydrogel microneedles as a diagnostic unit were prepared from double cross-linking of N-acryloyl-glycinamide and α-methylacrylic acid and hybridized with Eu3+ and terpyridine (TPy). The microneedles for transdermal GA@ZIF-8 delivery were completely dissolved in 2 min, which improved the cyclophosphamide-induced hair follicle recession in mice by reducing CD8+NKG2D+ T cells infiltration, inhibiting Jak receptor activation, and decreasing IL-15 and IFN-γ. Additionally, as a sensor unit, the microneedles rapidly absorbed water swelled when stabbed into the skin, and fluoresced red when exposed to 365 nm light. Zn2+ in the inter tissue fluid competes with Eu3+ in the TPy-Eu3+ complex and coordinates with Tpy, which triggers a change in fluorescence. Notably, the detection Zn2+concentration range was 10–8 M–10–1 M, and it was not disturbed by metal ions including Na+, K+, Mg2+, and Ca2+, suggesting that it is competent to be applied as a real-time chemosensor of Zn2+. Collectively, this newly designed system with both therapeutic and diagnostic functions provides a new strategy for treating zinc-related diseases.