From Zeolitic Imidazolate Framework-8 to Metal-Organic Frameworks (MOFs): Representative Substance for the General Study of Pioneering MOF Applications

Metal-organic frameworks(MOFs)have been intensely studied for the past few decades as an enormous family of highly tunable porous materials with promisingly applicable functionalities in adsorption,separation,catalysis,sensing,electrochemistry,and a great number of emerging purposes.As a classic MOF,zeolitic imidazolate framework-8(ZIF-8)is conventionally one of the very few MOF members that has been commercialized with considerable production.

以ZIF-70为固相微萃取涂层测定跑道面层成品中苯胺与2-氯苯胺

将沸石咪唑酯骨架材料(ZIF-70)制成固相微萃取涂层,结合气相色谱-质谱联用仪(GC-MS),建立了一种快速灵敏分析跑道面层成品中苯胺与2-氯苯胺的方法。实验优化条件:萃取温度60℃,萃取时间30 min,脱附温度230℃。在最优条件下,该方法测定样品中苯胺与2-氯苯胺的线性范围为50~5000 ng/g,检出限为1.8~2.1 ng/g,定量限为6.0~7.0 ng/g。该方法应用于实际跑道面层样品中苯胺与2-氯苯胺的检测,加标回收率为80.3%~98.2%。

Microfluidic one-step, aqueous synthesis of size-tunable zeolitic imidazolate framework-8 for protein delivery

Zeolitic imidazolate framework-8(ZIF-8)with porous structure,biocompatibility,and pH-sensitive release behavior is a promising nanoplatform for protein delivery.However,it is still a challenging task for a practical synthesis of protein-loaded ZIF-8 nanoparticles.Here we report an all-aqueous microfluidic reactor for one-step,rapid,and highly controlled synthesis of ZIF-8 nanoparticles with high protein loading at room temperature.Microfluidic reactor allows for an ultrafast(<35 ms),complete mixing of Zn2+ions and 2-methylimidazole(2-MIM)at different molecular ratios,leading to the formation of stable ZIF-8 nanoparticles with tunable sizes(13.2–191.4 nm)in less than 30 s.By pre-mixing various proteins such as bovine serum albumin(BSA)(isoelectric point(pI)=5.82),ovalbumin(OVA)(pI=4.82),or RNase A(pI=8.93)with 2-MIM,ZIF-8 nanoparticles can be synthesized with protein encapsulation efficiency over 97%.Among the nanoparticles with different sizes,25 nm ZIF-8 nanoparticles show the best performance in promoting the cellular uptake of protein payload.Using OVA as a model protein,we demonstrate that 25 nm ZIF-8 nanoparticles significantly enhance the cytosolic delivery of antigen,as indicated by the effective activation of dendritic cells.We anticipate that this microfluidic synthesis of nanomaterials may advance the emerging field of cytosolic protein delivery.

Zeolitic imidazolate framework-8 (ZIF-8) for drug delivery: a critical review

Zeolitie imidazolate framework-8(ZIF-8),composed of Zn ions and imidazolate ligands,is a class of metal-organic frameworks,which possesses a similar structure as conventional aluminosilicate zeolites.This material exhibits inherent porous property,high loading capacity,and pH-sensitive degradation,as well as excep-tional thermal and chemical stability.Extensive research effort has been devoted 10 relevant research aspects ranging from synthesis methods,property characterization to potential applications of ZIF-8.This review focuses on the recent development of ZIF-8 synthesis methods and its promising appications in drug delivery.The potential risks of using ZIF-8 for drug delivery are also summarized.

Facile fabrication of nanoscale hierarchical porous zeolitic imidazolate frameworks for enhanced toluene adsorption capacity

The development of a simple and facile synthesis route is a highly desirable but challenging process in the fabrication of nanoscale hierarchical porous zeolitic imidazolate frameworks(ZIFs).Herein we describe a facile method for rapidly synthesizing hierarchically porous ZIF-90 nanocrystals(particle sizes of~300 nm)using hydroxyl double salts as intermediates at room temperature.The as-synthesized ZIF-90 contained hierarchical porous structures developed using a crystalline interior and a random stack of multiple nanoparticles.Both the morphology and particle size of ZIF-90 nanocrystals could be tuned by controlling the molar ratio of ICA/Zn^(2+).Note that the as-synthesized hierarchically porous ZIF-90 nanocrystals exhibited higher thermal stability compared with the conventional ZIF-90.Because of the introduction of hierarchical porous structures,the resultant hierarchically porous ZIF-90 nanocrystals showed enhanced toluene adsorption capacity than those of conventional metal organic frameworks and zeolites.

An FPS-ZM1-encapsulated zeolitic imidazolate framework as a dual proangiogenic drug delivery system for diabetic wound healing

Inhibitors that target diabetes pathology-related signaling pathways have great therapeutic potential for diabetic wound healing.Metal–organic frameworks(MOFs)are increasingly popular drug delivery systems that have high loading capacity and can release their intrinsic metal ions to act as bioactive agents.In light of this,a receptor for advanced glycation end products(RAGE)inhibitor,4-chloro-N-cyclohexyl-N-(phenylmethyl)-benzamide(FPS-ZM1),was loaded into a cobalt(Co)-based MOF(zeolitic imidazolate framework-67,ZIF-67)to fabricate FPS-ZM1 encapsulated ZIF-67(FZ@ZIF-67)nanoparticles(NPs).As a result,FZ@ZIF-67 NPs could dually deliver Co ions and FPS-ZM1 in a controlled manner for over 14 days.Our in vitro study showed that FZ@ZIF-67 NPs not only enhanced angiogenesis by delivering Co ions but also released FPS-ZM1 to promote M2 macrophage polarization and attenuated high glucose(HG)-and/or inflammation-induced impairment of angiogenesis through RAGE inhibition.Moreover,in an in vivo study,FZ@ZIF-67 NPs markedly improved re-epithelialization,collagen deposition,neovascularization,and relieved inflammation in diabetic wounds in rats.This study not only provides a low-cost,effective,and synergistic proangiogenic bioactive agent but also demonstrates that targeting diabetes-related pathological signaling pathways is necessary to ameliorate vascularization impairment during diabetic wound healing.

Solid phase microwave-assisted fabrication of Fe-doped ZIF-8 for single-atom Fe-N-C electrocatalysts on oxygen reduction

Fe-N-C endowed with inexpensiveness,high activity,and excellent anti-poisoning power have emerged as promising candidate catalysts for oxygen reduction reaction(ORR).Single-atom Fe-N-C electrocatalysts derived from Fe-doped ZIF-8 represent the top-level ORR performance.However,the current fabrication of Fe-doped ZIF-8 relies on heavy consumption of time,energy,cost and organic solvents.Herein,we develop a rapid and solvent-free method to produce Fe-doped ZIF-8 under microwave irradiation,which can be easily amplified in combination with ball-milling.After rational pyrolysis,Fe-N-C catalysts with atomic FeN4 sites well dispersed on the hierarchically porous carbon matrix are obtained,which exhibit exceptional ORR performance with a half-wave potential of 0.782 V(vs.reversible hydrogen electrode(RHE))and brilliant methanol tolerance.The assembled direct methanol fuel cells(DMFCs)endow a peak power density of 61 mW cm^(-2) and extraordinary stability,highlighting the application perspective of this strategy.

Recent progress on synthesis of ZIF-67-based materials and their application to heterogeneous catalysis

In recent years,an increasing amount of interest has been dedicated to the synthesis and application of ZIF-67-based materials due to their exceptionally high surface area,tunable porosity,and excellent thermal and chemical stabilities.This review summarizes the latest strategies of synthesizing ZIF-67-based materials by exploring the prominent examples.Then,the recent progress in the applications of ZIF-67-based materials in heterogeneous catalysis,including catalysis of the redox reactions,addition reactions,esterification reactions,Knoevenagel condensations,and hydrogenation-dehydrogenation reactions,has been elaborately discussed.Finally,we end this work by shedding some light on the large-scale industrial production of ZIF-67-based materials and their applications in the future.

Enhanced adsorption of phenol from aqueous solution by carbonized trace ZIF-8-decorated activated carbon pellets

Trace zeolitic imidazolate framework-8(ZIF-8)-decorated activated carbon(AC)pellets were synthesized by a facile wet impregnation technique.After pyrolysis of the above composite material,the obtained carbon had a large surface area and pore volume,with traces of Zn on its surface.Subsequently,the capacity of the ZIF8/AC samples to adsorb and remove phenol from aqueous media was evaluated in both batch and column experimental setups.The equilibrium adsorption capacity reached 155.24 mg·g^(-1),which was 2.3 times greater than that of the pure AC(46.24 mg·g^(-1)).In addition,adsorption kinetics were examined by pseudofirst and pseudosecond order models,and adsorption isotherms were fitted into Langmuir and Freundlich equations.The adsorbent could be easily filtered from the solution and washed with methanol and water,while maintaining an efficiency N90% after 4 cycles.The above results make it a potentially reusable candidate for water purification.

Fabricating high-performance sodium ion capacitors with P2-Na_(0.67)Co_(0.5)Mn_(0.5)O_2 and MOF-derived carbon

Sodium ion capacitors(SICs) have been considered as a kind of promising devices to achieve both high power and energy density. However, it is still a challenge to achieve high energy output at elevated power delivery due to the poor rate capability of battery-type electrode materials and the kinetic mismatch with capacitor-type electrode materials. In this work, to fabricate SICs, P2-Na_(0.67)Co_(0.5)Mn_(0.5)O_2(P2-NCM)was chosen as the battery-type cathode material, and a typical metal-organic framework(MOF) material,zeolitic imidazolate framework-8(ZIF-8) derived carbon(ZDC) was utilized as the capacitor-type anode material. Due to the kinetic match and high-rate performance of both electrodes, the ZDC//P2-NCM SICs exhibited an energy output of 18.8 Wh kg^(-1) at a high power delivery of 12.75 kW kg^(-1).

A large-scale experimental study on CO_(2) capture utilizing slurry-based ab-adsorption approach

The increasing concentration of CO_(2) in atmosphere is deemed the main reason of global warming.Therefore,efficiently capturing CO_(2) from various sources with energy conservation is of great significance.Herein,a series of experiments were carried out to successfully test the slurry-based ab-adsorption method for continuously capturing CO_(2) in the large-scale cycled separation unit with cost-effect taking into account the scale-up criteria.A bubble column(with height 4900 mm and inner diameter 376 mm)and a desorption tank(with volume 310 L)are the essential components of the separation unit.The novel slurry used in this study was formed with zeolitic imidazolate framework-8 and 2-methylimidazole-water solution.The influence of operation conditions was investigated systematically.The results show that increasing sorption pressure and slurry height level,decreasing gas volume flow and sorption temperature are beneficial for separation processes.The volume fraction of CO_(2) in the feed gas was also studied.Although the scale-up effect had been observed and it was found that it exerted a negative effect on CO_(2) capture,depending on experimental conditions,CO_(2) removal efficiency could still reach 85%-95%and the maximum CO_(2) loading in the recycled slurry could be up to0.007 mol·L-1·kPa-1.Furthermore,the slurry-based method could be operated well even under very moderate regeneration conditions(333 K and 0.05 MPa),which means that the novel approach shows greater energy conservation than traditional amine absorption methods.

Accelerated reconstruction of ZIF-67 with significantly enhanced glucose detection sensitivity

Research on metal-organic framework(MOF)-based non-enzymatic glucose sensors usually ignores the impact of the surface reconstruction degree of MOF on the activity of catalyzing glucose oxidation.In this work,we choose zeolitic imidazolate framework-67(ZIF-67),which is commonly used in glucose sensing,as a representative to investigate the influence of reconstruction degree on its structure and glucose catalytic performance.By employing the electrochemical activation strategy,the activity of ZIF-67 in catalyzing glucose gradually increased with the prolongation of the activation time,reaching the optimum after 2 h activation.The detection sensitivity of the activated ZIF-67 was 19 times higher than that of the initial ZIF-67,and the limit of detection(LOD)was lowered from 7 to 0.4μM.Our findings demonstrate that the oxidation degree of ZIF-67 deepened rapidly with continuously activation and was basically reconstructed to CoOOH after 2 h activation,accompanied by a morphological change from cuboctahedral to flower-like.Simultaneously,theoretical investigation revealed that ZIF-67 is not suitable as a stable glucose sensor electrode since the adsorbed glucose molecules hasten the dissociation of ligands and the breaking of Co-N bond in ZIF-67.Therefore,our work has important implications for the rational design of next-generation MOF-based glucose sensors.

A novel structure of ultra-high-loading small moleculesencapsulated ZIF-8 colloid particles

The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8(ZIF-8)-based colloid particles(CPs)with an amorphous ZIF-8 skin.This encapsulation structure achieves an ultra-high loading rate(LR)of 90%(i.e.,9 mg doxorubicin(DOX)per 1 mg ZIF-8)for DOX and the protection of DOX from leaking.Notably,to deliver unit-dose drug,this ultra-high LR of 90%significantly reduces the usage of ZIF-8 to 1.2%(2 orders of magnitude)compared to that of DOX@ZIF-8 with a 10%LR,in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored.Safety,drug delivery efficacy,scale-up ability,and universality of this encapsulation structure have been further verified.Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.

Metal-organic framework hybrid materials of ZIF-8/RGO for immobilization of D-amino acid dehydrogenase

Immobilization of D-amino acid dehydrogenase(DAADH)by the assembly of peptide linker was studied for the biosynthesis of Dphenylalanine.Hybrid material of zeolitic imidazolate framework-8(ZIF-8)combined with reduced graphene oxide(RGO)was applied for the immobilization of DAADH from Ureibacillus thermosphaericus.The recovery rate of DAADH/ZIF-8/RGO was 165.6%.DAADH/ZIF-8/RGO remained 53.4%of its initial activity at 50°C for 10 h while the free enzyme was inactivated.DAADH/ZIF-8/RGO maintained 70.5%activity in hyperalkaline solution with pH 12.Kinetic parameters indicated that DAADH/ZIF-8/RGO had greater affinity of phenylpyruvate as V_(max)/K_(m)of DAADH/ZIF-8/RGO was 1.27-fold than free enzyme.After seven recycles,the activity of DAADH/ZIF-8/RGO remained 64.3%.Furthermore,one-step separation and in situ immobilization of DAADH by ZIF-8/RGO/Ni was carried out with 1.5-fold activity enhancement.Combining peptide linker and metal-organic framework(MOF)immobilization,thermostability and activity of the immobilized DAADH were significantly improved.

ZIF-8 coated gold nanospheres: A multi-responsive drug delivery system promoting the killing effect of photothermal therapy against osteosarcoma cells

Photothermal therapy(PTT)has been widely used in the treatment of tumors,but its efficacy is greatly limited by the inability of precise drug delivery and the increase of heat shock proteins(HSPs)caused by high temperature.This article describes a therapeutic strategy to enhance PTT with starvation therapy in conjunction with ferroptosis mechanism.A nanoparticle platform ZIF-8@GA was constructed by wrapping together glucose oxidase(GOX)and gold nanospheres(AuNPs)loaded with dihydroartemisinin(DHA)with zeolitic imidazolate framework-8(ZIF-8).This platform can take advantage of the micro-environment of osteosarcoma(OS)cells,featuring low pH and high reactive oxygen species(ROS),for precision drug delivery.GOX can effectively catalyze glucose to produce gluconic acid and H_(2)O_(2),and DHA can also induce ROS production in OS cells.ROS produced by GOX and DHA can further generate lipid peroxidation(LPO)and lead to ferroptosis of OS cells.At the same time,ROS and LPO produced can inhibit the expression of HSPs,thereby increasing the therapeutic effect of PTT.In vitro experiments show that the nanoparticles are pH and ROS responsive.1μg/mL GOX combined with 0.2μg/mL DHA promotes ferroptosis of OS cells,and increases the killing effect of near-infrared(NIR)on OS cells.Further in vivo experiments showed that the nano drug-delivery platform combined with PTT can effectively inhibit the growth of OS cells.Meanwhile,this study provides a new idea for the treatment of OS with biomaterials combined with various treatment methods.

Design of novel RGO/2D strip-like ZIF-8/DMAOP ternary hybrid structure towards high-efficiency microwave absorption, active and passive anti-corrosion, and synergistic antibacterial performance

In order to meet the requirements of the marine environment for microwave absorption(MA)materials,we put forward the strategy of constructing multi-functional composite materials,which integrate microwave absorption,anti-corrosion,and antibacterial properties.Herein,graphene oxide(GO)was used as a template to induce the growth of zeolitic imidazolate framework-8(ZIF-8),simultaneously as a two-dimensional(2D)nanocontainers to load corrosion inhibitors to achieve pH-responsive and self-healing properties.Finally,quaternary ammonium salt(dimethyl octadecyl(3-trimethoxylsilyl propyl)ammonium chloride(DMAOP))and sodium ascorbate(VCNa)were introduced to achieve synergistic antibacterial activity and the reduction of GO.The 2D strip-like structure of ZIF-8 was due to the confined growth induced by the electrostatic attraction between ZIF-8 and GO sheets.The as-obtained reduced GO(RGO)/ZIF-8/DMAOP5 exhibited excellent microwave absorption(MA)properties,with a minimum reflection loss(RL)value of-47.08 dB at 12.73 GHz when the thickness was 2.8 mm.Moreover,the effective absorption bandwidth reached 6.84 GHz.After soaking in 3.5%NaCl solution for 35 days,the RGO/ZIF-8/DMAOP5-0.7%coating still achieved an impedance value of 4.585×107Ω·cm^(2) and a protective efficiency of 99.994%,providing superior anti-corrosion properties.In addition,fantastic antibacterial activity was obtained,with the antibacterial rates of RGO/ZIF-8/DMAOP_(10) reaching 99.39%and 100%against Escherichia coli and Staphylococcus aureus.This work could open new avenues towards the development of a new generation of multifunctional MA materials.

The“mediated molecular”-assisted construction of Mo_(2)N islands dispersed on Co-based nanosheets for high-efficient electrocatalytic hydrogen evolution reaction

The rational design of the catalysts with easily-accessible surface and high intrinsic activity is desirable for electrocatalytic hydrogen evolution reaction(HER).Here,we reported the construction of two-dimensional(2D)Co-Mo nitrides based heterojunctional catalyst for efficient HER based on a“mediated molecular”assisted route.The 2D Co(OH)_(2)sheet reacted partially with the“mediated molecular”(2-methylimidazole(2-MIM))to form zeolitic imidazolate framework(ZIF)-67 at surface,giving ZIF-67/Co(OH)_(2)sheets.The ZIF-67 combines with[PMo_(12)O_(40)]^(3−)cluster(PMo_(12))due to the interaction of mediated molecular with PMo_(12),producing 2D Mo-Co-2MIM/Co(OH)_(2)bimetallic precursor.After controlled nitriding,the Mo_(2)N islands dispersed on 2D porous Co-based sheets were formed.A series of characterizations and density functional theory(DFT)calculation indicated the formation of a close contact interface,which promotes the electron transfer between Mo and Co components,enhances the electron migration/redistribution and redistribution and down-shift of d-band center and thus gives a high intrinsic activity.The 2D characteristics make the catalyst more accessible contact sites,which is favourable to promot the HER.The tests showed that the optimized catalyst exhibits an onset potential of 0 mV and an overpotential of 10 mA·cm^(−2)at 35.0 mV,which is quite close to that of Pt/C catalyst.It also exhibits an activity superior to Pt/C at high current density(>100 mA·cm^(−2)).A good stability of the catalyst was achieved with no significant decay for 100 h of continuous operation.The electrolytic cell composed of optimized catalyst and P-NiFe-layered double hydroxide(LDH)can be driven by low voltage(only 1.47 V)to reach a current density of 10 mA·cm^(−2).

Defects enriched hollow porous Co-N-doped carbons embedded with ultrafine CoFe/Co nanoparticles as bifunctional oxygen electrocatalyst for rechargeable flexible solid zinc-air batteries

The construction and design of highly efficient and inexpensive bifunctional oxygen electrocatalysts substitute for noble-metal-based catalysts is highly desirable for the development of rechargeable Zn-air battery(ZAB).In this work,a bifunctional oxygen electrocatalysts of based on ultrafine CoFe alloy(4-5 nm)dispersed in defects enriched hollow porous Co-N-doped carbons,made by annealing SiO2 coated zeolitic imidazolate framework-67(ZIF-67)encapsulated Fe ions.The hollow porous structure not only exposed the active sites inside ZIF-67,but also provided efficient charge and mass transfer.The strong synergetic coupling among high-density CoFe alloys and Co-N_(x) sites in Co,N-doped carbon species ensures high oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)activity.First-principles simulations reveal that the synergistic promotion effect between CoFe alloy and Co-N site effectively reduced the formation energy of from O^(*)to OH^(*).The optimized CoFe-Co@PNC exhibits outstanding electrocatalytic stability and activity with the overpotential of only 320 mV for OER at 10 mA·cm^(−2) and the half-wave potential of 0.887 V for ORR,outperforming that of most recent reported bifunctional electrocatalysts.A rechargeable ZAB constructed with CoFe-Co@PNC as the air cathode displays long-term cyclability for over 200 h and high power density(152.8 mW·cm^(−2)).Flexible solid-state ZAB with our CoFe-Co@PNC as the air cathode possesses a high open circuit potential(OCP)up to 1.46 V as well as good bending flexibility.This universal structure design provides an attractive and instructive model for the application of nanomaterials derived from MOF in the field of sustainable flexible energy applications device.

Atomic layer deposition-induced integration of N-doped carbon particles on carbon foam for flexible supercapacitor

Flexible devices have attracted abundant attention in energy storage systems.In this paper,we presented a novel approach for fabricating flexible supercapacitor based on metal organic frameworks-derived material.In this approach,a uniform zeolitic imidazolate frameworks-8 layer with a high mass loading was deposited on a flexible carbon foam(CF)skeleton efficiently by the induction of a uniform ZnO nanomembrane prepared via an atomic layer deposition technique.A flexible N-doped carbon particle-carbon foam(N-CP-CF)composite with a hierarchically porous structure and a large specific surface area(i.e.,538 m^(2) g^(-1))was obtained in a subsequent pyrolysis process.The resultant materials have the excellent electrochemical performance(i.e.,a high specific capacitance of 300 F g^(-1) and a high energy density of 20.8 W h kg^(-1)).The N-CP-CF composite can provide a stable capacitance(i.e.,250 F g^(-1))and an energy density(i.e.,17.36 W h kg^(-1))under large deformation(25% of original thickness).This work could propose a promising strategy in fabrication of flexible electrode with a large potential towards energy storage applications in the future.

Synthesis and Antibacterial Properties of ZIF-8/Ag-Modified Titanium Alloy

The loosening of implant due to bacterial infection brings great difficulties to the implantation of bionic titanium devices.In this study,the Zeolitic Imidazolate Framework 8(ZIF-8)and silver ions were added to the surface of titanium alloy to obtain a uniform coating,which has nice biological activity and antibacterial property.The material structure characterizations,such as X-ray diffraction(XRD),scanning electron microscope(SEM),X-ray photoelectron spectroscopy(XPS),proved that titanium is successfully modified with ZIF-8 and silver ions.It has micro-and nano-level characteristics,rough porous morphology,and excellent apatite inducing ability.The water contact angle experiment shows that the addition of ZIF-8 greatly increases the hydrophilicity of material,which provides conditions for the attachment of osteoblasts.The polarization curve obtained from the electrochemical test proves that the addition of ZIF-8 coating improves the corrosion resistance of titanium.The release of silver ion has a strong growth inhibitory effect on E.coli,and exhibits excellent antibacterial properties.Therefore,the preparation of ZIF-8/Ag coatings on 3D printed titanium provides a new option for the development of orthopedic implants.