Synthesis Of Zeolitic Imidazolate Frameworks Research Articles

Fabrication of hydrophobic drug-loaded Zeolitic Imidazolate Framework-8 (ZIF-8) for enhanced anti-bacterial activity

Current study presents a novel approach for constructing small hydrophobic biomolecules embedded within zeolitic imidazolate framework-8 (ZIF-8) with exceptional antibacterial properties. In this method, ZIF-8 is synthesized from zinc acetate and 2-methylimidazole in the presence or absence of small hydrophobic bioactive molecules like rutin, rosmarinic acid, and morin. Scanning electron microscopy (SEM) analysis reveals that the synthesized ZIF-8 nanoparticles exhibit mostly hexagonal shape with size 200 nm which is further increased upon drug encapsulation. The synthesis of ZIF-8 and drug-loaded ZIF-8 is confirmed through FTIR, UV–vis spectroscopy, XRD, TGA, and EDX analyses. Zeta potential measurements show values ranging from -14.5 to -23.97 mV for both ZIF-8 and drug-loaded ZIF-8 nanoparticles. The drug loading content is determined to be 5 %, 9 %, and 16 % for morin, rutin, and rosmarinic acid, respectively. All the drug-loaded ZIF-8 formulations exhibit a pH-dependent drug release pattern, with maximal drug release observed at lower pH levels. Most importantly, these formulations demonstrate potent antibacterial activity against both Gram-positive (Enterococcus faecalis and Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial strains. Specifically, ZIF-8/RUT exhibit maximum zone of inhibition (ZOI ∼ 51 mm) against all tested bacterial strains. ZIF-8/MOR and ZIF-8/RUT exhibit MIC values ranging from 2.0 to 3.0 mg/mL and MBC values from 6 to 9 mg/mL against all the tested bacteria. Among the formulations, ZIF-8/MOR and ZIF-8/RUT exhibit synergistic antibacterial effect, whereas ZIF-8/RMA possess less antibacterial potency against all the tested bacteria and mostly exhibit additive effect. Our findings suggest that these newly developed nano-formulations hold potential for the creation of highly effective antibacterial agents.

Tribological Performance and Enhancing Mechanism of 3D Printed PEEK Coated with In Situ ZIF-8 Nanomaterial.

Polyether ether ketone (PEEK) is esteemed as a high-performance engineering polymer renowned for its exceptional mechanical properties and thermal stability. Nonetheless, the majority of polymer-based lubricating materials fail to meet the contemporary industrial demands for motion components regarding high speed, heavy loading, temperature resistance, and precise control. Utilizing 3D printing technology to design and fabricate intricately structured components, developing high-performance polymer self-lubricating materials becomes imperative to fulfill the stringent operational requirements of motion mechanisms. This study introduces a novel approach employing 3D printing technology to produce PEEK with varying filling densities and conducting in situ synthesis of zeolitic imidazolate framework (ZIF-8) nanomaterials on its surface to enhance PEEK's frictional performance. The research discusses the synthetic methodology, characterization techniques, and tribological performance evaluation of in situ synthesized ZIF-8 nanomaterials on PEEK surfaces. The findings demonstrate a significant enhancement in frictional performance of the composite material under low-load conditions, achieving a minimum wear rate of 4.68 × 10-6 mm3/N·m compared to the non-grafted PEEK material's wear rate of 1.091 × 10-5 mm3/N·m, an approximately 1.3 times improvement. Detailed characterization and analysis of the worn surface of the steel ring unveil the lubrication mechanism of the ZIF-8 nanoparticles, thereby presenting new prospects for the diversified applications of PEEK.

Organic-inorganic hybrid ZIF-8/MXene/cellulose-based textiles with improved antibacterial and electromagnetic interference shielding performance

Despite the tremendous efforts on developing antibacterial wearable textile materials containing Ti3C2Tx MXene, the singular antimicrobial mechanism, poor antibacterial durability, and oxidation susceptibility of MXene limits their applications. In this context, flexible multifunctional cellulosic textiles were prepared via layer-by-layer assembly of MXene and the in-situ synthesis of zeolitic imidazolate framework-8 (ZIF-8). Specifically, the introduction of highly conductive MXene enhanced the interface interactions between the ZIF-8 layer and cellulose fibers, endowing the green-based materials with outstanding synergistic photothermal/photodynamic therapy (PTT/PDT) activity and adjustable electromagnetic interference (EMI) shielding performance. In-situ polymerization formed a MXene/ZIF-8 bilayer structure, promoting the generation of reactive oxygen species (ROS) while protecting MXene from oxidation. The as-prepared smart textile exhibited excellent bactericidal efficacy of >99.99 % against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) after 5 min of NIR (300 mW cm−2) irradiation which is below the maximum permissible exposure (MPE) limit. The sustained released Zn2+ from the ZIF-8 layer achieved a bactericidal efficiency of over 99.99 % within 48 h without NIR light. Furthermore, this smart textile also demonstrated remarkable EMI shielding efficiency (47.7 dB). Clearly, this study provides an elaborate strategy for designing and constructing multifunctional cellulose-based materials for a variety of applications.

Innovative Synthesis of Zeolitic Imidazolate Framework by a Stovetop Kitchen Pressure Cook Pot for Triboelectric Nanogenerator

This study presents a novel approach utilizing solvothermal techniques to synthesize zeolitic imidazolate framework (ZIF‐4) particles. Various properties of the ZIF‐4 particles are investigated to shed light on the structural and morphological characteristics. These ZIF‐4 particles act as a positive triboelectric layer in the fabrication of a triboelectric nanogenerator (TENG) designed for powering electronic devices. The solvothermal‐assisted synthesis ensures the controlled and efficient production of ZIF‐4, optimizing its characteristics for enhanced performance in the TENG. The generated TENG, based on ZIF‐4 particles, determines promising capabilities in converting mechanical energy into electrical power. The highest power of TENG is obtained to be 18 μW at a load resistance of 50 MΩ. This work contributes major insights to the search for sustainable and effective power solutions for electronic gadgets. It emphasizes the potential of ZIF‐4 as a crucial triboelectric material, demonstrating its importance in the advancement of TENGs.

Less solvent solid state reaction method synthesis of zeolitic imidazolate frameworks and the adsorption properties of their derived carbon materials

In recent years, a variety of nanomaterial synthesis methods have been used to explore the preparation of metal–organic frameworks (MOFs). The zeolitic imidazolate frameworks (ZIFs), are typically synthesized through high cost and environmentally unfriendly solvothermal methods, require a large amount of organic solvents, and have extremely low yields. Therefore, exploring scalable and environmentally friendly synthesis routes for ZIFs is crucial. The metal oxide and 2-methylimidazole are completely converted into submicron size ZIFs in stoichiometric ratio via less solvent solid state reaction (LSR) method. The ZIFs synthesized by LSR method have good crystallinity, large specific surface area, and the use of tiny solvent amount can achieve a yield of nearly 100%, which solves the problems of low yield and serious waste of solvent in the synthesis of ZIFs by traditional methods. Additionally, the fabricated ZIFs derived materials through high-temperature pyrolysis have high specific surface area, nitrogen rich content, and excellent chemical stability, being favorable for promoting the adsorption of organic dyes. The adsorption capacity of ZIF-8 derived materials fabricated by the LSR method for organic dyes is significantly better than that of ZIF-67 and bimetallic ZIFs (BZIFs) derived materials. Compared with the traditional method, the LSR method is a green and scalable manner to synthesize submicron ZIFs materials, paving the way for the preparation of various ZIFs with different metal centers, and also providing a new strategy for the commercial production of ZIFs derived materials widely used in the environment protection.

Green conversion of waste alkaline battery material to zeolitic imidazolate framework-8 and its iodine capture mechanism

Zeolitic imidazolate framework-8 (ZIF-8) exhibits excellent performance in capturing iodine. However, the solvent-based procedures and raw materials for ZIF-8 synthesis often lead to secondary pollution. We developed a solvent-minimizing method for preparing ZIF-8 via ball milling of raw material obtained from spent alkaline batteries, and studied its iodine-capture performance and structural changes. Exposure of the ZIF-8 to iodine vapor for 60 min demonstrated that it exhibited industrially competitive iodine-capture performance (the adsorbed amount reaches to 1123 mg g−1 within 60 min). Spectroscopic studies showed that ZIF-8 underwent a structural transformation upon iodine loading. Iodine molecules were adsorbed onto the surface of ZIF-8 and also formed C–I bond with the methyl groups on the imidazole rings, reducing iodine release. This work represents a comprehensive revelation of long-range order and short-range order evolution of ZIF-8 during iodine vapor adsorption over time. Moreover, this green synthesis of ZIF-8 is of lower cost and generates fewer harmful by-products than existing methods, and the produced ZIF-8 effectively entraps toxic iodine vapor. Thus, this synthesis enables a sustainable and circular material flow for beneficial utilization of waste materials.

Sustainable Synthesis of Zeolitic Imidazolate Frameworks at Room Temperature in Water with Exact Zn/Linker Stoichiometry.

Zeolitic imidazolate frameworks (ZIFs) are widely used MOFs because of certain characteristics, but also because they can be prepared at room temperature using water as the unique solvent. However, these a priori sustainable conditions inevitably entail a huge and somehow unusable excess of linker. Here, we present the formation of ZIFs at room temperature in water, starting from mixtures with a linker/metal ratio of two, that is, coinciding with the stoichiometry found in the final MOFs, in the presence of amines. ZIF-8 can be prepared with triethylamine (TEA), giving a yield of Zn of 96.6%. Other bases, like NaOH, tetraethylammonium hydroxide or ammonium hydroxide, do not lead to ZIF-8 under the same conditions. The so-obtained ZIF-8 contains TEA inside its cavities, making it less porous than its conventionally prepared counterparts. Amine can be removed by mild thermal treatments (200-250 °C). Such thermal treatments induce the generation of g-C3N4-like species which could give added value to these materials as potential photocatalysts, increasing their affinity to CO2, as proved in this work. This methodology can be successfully extended to other amines, like N,N-dicyclohexylmethylamine, as well as to other prepared ZIFs, like Co-based ZIF-67, isostructural to ZIF-8.

Synthesis of zeolitic imidazolate framework-8 using an electric field in a gelled medium

A direct electric field can be used to control the synthesis of the metal–organic framework in a gelled medium. The average size and dispersity of the crystals can be directed by the electric field strength.

Controlled synthesis of metal-organic frameworks via AC electrokinetic mixing-assisted microfluidics: A case study of ZIF-8

Metal-organic frameworks (MOFs) have great potential for a wide range of applications given their flexible structures and pore networks. Morphology control directly affects the properties and applications of MOFs. Unfortunately, governing the desired dimension and shape of MOFs is often limited by macrosystems that require organic solvents and additives while including time-consuming treatments. Microfluidics as a practical alternative provides precise manipulation of microscale liquid, has the potential to be a superior platform for directed crystal generation. Here we reported an AC electrokinetic (EK) mixing-assisted micro-synthesis method, which allowed the actively controlled synthesis of MOFs in aqueous phase. The effects of flow rate, molar-ratio of precursors, electric field intensity, and frequency on the synthesis of zeolitic imidazolate framework-8 (ZIF-8) were investigated. Using this method, the particle size of ZIF-8 were varied, and the geometry were changed between flower-like polyhedra, cubes, spheres, and rhombic dodecahedra. Furthermore, the synthesized various ZIF-8 provide different levels of immobilization sites based on their morphological deviations. The flower-like cubic ZIF-8 had defect structures and exhibited a maximum horseradish peroxidase (HRP) loading of about 16%. The study provides a simple, green and reliable tuning strategy for breaking the single morphological form of MOFs to enhance their physicochemical properties.

Synthesis, characterization, and application of ZIF-8 for removal of Cd, Ni, and Pb ions from aqueous solutions: Optimization of the process by Response Surface Methodology (RSM) based on Central Composite Design (CCD) technique

A Zeolitic imidazolate framework-8 (ZIF-8) was synthesized by the solvothermal method of zinc nitrate hexahydrate and 2-methylimidazole in DMF to remove Cd(II), Ni(II), and Pb(II) ions from aqueous solutions. The synthesized ZIF-8 was distinguished by XRD, FT-IR, BET, SEM, EDX, TEM methods. Several significant variables were optimized with response surface methodology (RSM) to obtain the highest removal of metal ions. According to the achieved results, the aqueous solution pH values of 6.5, 6.5, and 6.0, ZIF-8 dosages of 0.05, 0.06, and 0.05 g⸳L-1, and metal ions initial concentrations of 50, 60, and 60 mg⸳L-1 were chosen as the optimum amount of these variables for Cd(II), Ni(II), and Pb(II) ions adsorption from solution, respectively. The equilibrium time for metal ions adsorption was found at 50 min. Three-dimensional plots demonstrate relationships between the metal ion uptakes with the paired factors, which illustrate the behavior of the sorption system in a batch process. Based on the experimental results and model parameters, maximum adsorption efficiencies were achieved 89.76, 72 and 68.43% for Cd(II), Ni(II) and Pb(II), respectively. It can be suggested that the synthetized ZIF-8 has excellent potential as an effective adsorbent and used for heavy metal sorption from water environment.

Optimizing the Green Synthesis of ZIF-8 by Reactive Extrusion Using In Situ Raman Spectroscopy

We report the scale-up of a batch solid synthesis of zeolitic imidazolate framework-8 (ZIF-8) for reactive extrusion. The crystalline product forms in the extruder directly under the mixture of solid 2-methylimidazole and basic zinc carbonate in the presence of a catalytic amount of liquid. The process parameters such as temperature, liquid type, feeding rate, and linker excess were optimized using the setup specifically designed for in situ Raman spectroscopy. Highly crystalline ZIF-8 with a Brunauer–Emmett–Teller (BET) surface area of 1816 m2 g–1 was quantitatively prepared at mild temperature using a catalytic amount of ethanol and a small excess of the linker. Finally, we developed a simple and comprehensive approach to evaluating the environmental friendliness and scalability of metal–organic framework (MOF) syntheses in view of their large-scale production.

A novel core-shell structured Fe@CeO2-ZIF-8 catalyst for the reduction of NO by CO

Zeolitic imidazolate framework-8 (ZIF-8) based catalysts are considered as promising candidates for the selective catalytic reduction of NO by CO (CO-SCR) reaction due to their large specific surface area. However, the structure of ZIF-8 will be damaged during the synthesis procedure of the catalyst, leading to a decrease in their physical properties, which in turn affects the catalytic performance of the catalyst. Herein, a CeO2-ZIF-8 core-shell structure was synthesized and doped with Fe, resulting in the formation of Fe@CeO2-ZIF-8, for CO-SCR reaction. Characterization results show that the Fe@CeO2-ZIF-8 core-shell catalyst has better morphology, thermal stability, and higher specific surface area than the FeCe co-impregnated ZIF-8 catalyst (FeCe@ZIF-8 (IM)). Moreover, the reducibility of the reactive Fe species in the Fe@CeO2-ZIF-8 core-shell catalyst is also enhanced. As a result, the Fe@CeO2-ZIF-8 core-shell catalyst exhibited higher low-temperature CO-SCR catalytic activity with its NO conversion reaching 99% at 250 °C versus the FeCe@ZIF-8 (IM) catalyst (89% at 250 °C). The experimental results were further verified by density functional theory (DFT) calculations including Electron Localization Function (ELF), Valence Charge Density Difference (VCDD), Projected Density of States (PDOS) and Bader charge analyses. The calculation results revealed that the core-shell configured Fe@CeO2-ZIF-8 catalyst has a stronger active metal-support charge transfer and better capacity for the adsorption of the reactants. The reaction mechanism over Fe@CeO2-ZIF-8 core-shell catalyst was investigated via in situ DRIFTS experiments, and results showed that the nitro compounds and formate species are critical intermediates in this reaction at a higher temperature range (300–350 °C). This work provides a new strategy for the synthesis of ZIF-8 based catalysts with better properties for CO-SCR reaction.

Sustainable Synthesis of Zeolitic Imidazolate Framework-8 Nanoparticles and Application in the Adsorption of the Drug Chlorhexidine

In an attempt to synthesize nanomaterial concerning chemistry, the sustainable synthesis of Zeolitic Imidazolate Framework-8 (ZIF-8) nanoparticles by a low-cost approach through the recycling of waste mother liquors was explored and then indicated the potential to remove chlorhexidine (CHLX) from an aqueous solution. ZIF-8 was produced under solvothermal reaction at 25°C and characterized by Fourier Transform Infrared Spectroscopy, X-ray diffraction, adsorption/desorption of N<sub>2</sub>, dynamic light scattering and contact angle. The water Chemical stability test was conducted using ZIF-8 and it was immersed in pure water for 24 h at room temperature. Batch-type adsorption was used to check the potential of ZIF-8 (first and second generation) for the adsorption of the chlorhexidine with initial chlorhexidine concentration (0.05, 0.06 and 0.07 mol/L), agitation time (1, 3.5 and 6 h) and the mass of nano-adosrbent (0.04, 0.05 and 0.06 g). Process optimization was performed through a Factorial experimental design. The optimum conditions were selected for the nano-adsorbent mass of 0.04 g, agitation time of 1 h and initial chlorhexidine concentration 0.07 mmol/L. The ZIF-8 sustainable synthesis was efficient and generated a crystalline nanomaterial. The result shows that ZIF-8 is stable in water under ambient conditions. The ZIF-8 first generation and ZIF-8 second generation exhibit a high adsorption capacity (27.17 mg/g and 30.96 mg/g). It was found that, under the synthesis conditions, the recycled mother liquor user did not affect the final characteristics of this nanomaterial. The results indicated that the initial concentration of chlorhexidine and nano-adsorbent mass influenced the adsorption capacity. Experimental design provided the process optimum conditions (1 h, 0.04 g of adsorbent mass and 0.07 mmol/L).

Controllable synthesis of zeolitic imidazolate frameworks and the peanut shell carbon composite for sensitive and selective detection of Pb2+ and Cd2+ ions

Zeolitic imidazolate frameworks (ZIF) and the peanut shell carbon (PSC) composite (ZIF-8 @PSC) nanocomposite is successfully fabricated and exhibits superior current response for simultaneously detecting Pb2+ and Cd2+. The obtained composite has been characterized via SEM, TEM, XRD, FTIR, N2 adsorption-desorption methods. The suitable pore structure of ZIF-8 @PSC with the highest mesoporous ratio (ca. 11%) is conducive to mass transportation and charge transfer. The available specific surface area (236.6 m2 g−1), the lowest internal resistance (81.8 Ohm) as well as the synergistic effect between ZIF and PSC in ZIF-8 @PSC(4−1) electrode contribute to the enhanced current signals for the detection of Pb2+ and Cd2+ in aqueous solution. Additionally, the cyclic voltammetry investigation reveals that the kinetic process of the target heavy metal ions on the surface of the ZIF-8 @PSC(4−1) electrode is controlled by diffusion, which is verified by the Warburg impedance in low frequency region. Under the optimum conditions, the peak currents are linearly related with the concentration of Pb2+ and Cd2+ in the range of 0.1–8 µM (Pb2+) and 0.06–9 µM (Cd2+), and the corresponding limit of detection is 8.25 nM (S/N = 3) and 16 nM (S/N = 3), respectively, which are superior to other reported results. Based on the outstanding selectivity, stability, repeatability, and reproducibility, the analytical performance for the detection of the metal ions is assessed individually and simultaneously. It is found that the obtained method exhibits simultaneous sensing ability toward Cd(II) and Pb(II). During the multi-component sample, the detection and quantification of Pb(II) is more sensitive. Finally, the proposed method is applied to detect Pb2+ and Cd2+ in domestic sewage and satisfactory results have been achieved.

ZIF-8 and Its Magnetic Functionalization as Vehicle for the Transport and Release of Ciprofloxacin.

The use of nanomaterials for the controlled release of drugs aims to enhance their effectiveness, especially when poorly soluble in water, and achieve their rapid, localized, and effective administration. The present study focuses on the use of a Zeolitic Imidazolate Framework-8 (ZIF-8) as vehicle for the transport and controlled release of the antibiotic ciprofloxacin (CIP) as model due to its favorable physicochemical characteristics. The objective is to synthesize the ZIF-8 material loaded with CIP through encapsulation for subsequent release of the drug in neutral and acid physiological media. In addition, functionalization of the CIP/ZIF compound with magnetic nanoparticles (NP) was sought to increase its traceability through the possible use of magnetic fields. Characterizations by XRD, FT-IR, SEM-EDX, and TGA showed a satisfactory synthesis of both pure ZIF-8 and ciprofloxacin-loaded ZIF-8, with high crystallinity and thermal stability. The release profiles showed an abrupt initial release that stabilized over time. A much higher release (20-80% greater) was obtained in acid versus neutral pH in all cases, attributable to the collapse of the ZIF-8 structure in acid media. In addition, functionalization of the material with iron NPs did not affect the behavior of the system during drug release. Antimicrobial activity tests against E. coli and S. aureus showed that ZIF-8 per se exerts antimicrobial activity, while the compounds CIP/ZIF and magnetic CIP/ZIF increased the antimicrobial capacity of pure CIP by 10-20%. The ZIF-8 system has high potential as a drug carrier and release agent for the treatment of diseases, especially those that cause acidification of the cellular environment, achieving a rapid, localized, and targeted action with the possibility of achieving traceability of the system after its magnetic functionalization.

Synthesis of zeolitic imidazolate framework-8 (ZIF-8) using different solvents for lead and cadmium adsorption

Synthesis of zeolitic imidazolate framework-8 (ZIF-8) using different solvents for lead and cadmium adsorption

Influence of Salt Doping on the In Situ Synthesis of Zeolitic Imidazolate Framework-8 in Poly(diallyldimethylammonium chloride)/Poly(sodium-p-styrenesulfonate) Polyelectrolytes Complexes

Influence of Salt Doping on the In Situ Synthesis of Zeolitic Imidazolate Framework-8 in Poly(diallyldimethylammonium chloride)/Poly(sodium-p-styrenesulfonate) Polyelectrolytes Complexes

In Situ Synthesis of Multivariate Zeolitic Imidazolate Frameworks for C2 H4 /C2 H6 Kinetic Separation.

Herein, a new approach for the in situ synthesis of zeolitic imidazolate framework (ZIF) nanoparticles with triple ligands, referred to as Sogang ZIF-8 (SZIF-8), is reported for enhanced C2 H4 /C2 H6 kinetic separation. SZIF-8 consists of tetrahedral zinc metals coordinated with tri-butyl amine (TBA), 2,4-dimethylimidazole (DIm), and 2-methylimidazole (MIm). SZIF-8(x) with different DIm contents in x (up to 23.2 mol%) are synthesized in situ because TBA preferably deprotonates DIm ligands due to the much lower pKa of DIm over MIm, allowing for the Zn-DIm coordination. The Zn-DIm coordination reduces the window size of ZIF-8 with suppressed linker flipping motion due to bulky DIm ligands and simultaneously enhances the interfacial interaction between 6FDA-DAM polyimide (6FDA) and SZIF-8 via electron donor-acceptor interactions. Consequently, 6FDA/SZIF-8(13) mixed matrix membrane exhibits an excellent C2 H4 permeability of 60.3 Barrer and C2 H4 /C2 H6 selectivity of 4.5. The temperature-dependent transport characterization reveals that such excellent C2 H4 /C2 H6 kinetic separation is attained by the enhancement in size discrimination-based energetic selectivity. Our hybrid multi-ligand approach can offer a useful tool for the fine-tuning of molecular structures and textural properties of other metal organic frameworks.

Comparative life cycle assessment on zeolitic imidazolate framework-8 (ZIF-8) production for CO2 capture

Metal-organic frameworks (MOFs) combine the advantages of both organic and inorganic materials. Among the synthesized MOFs, ZIF-8 is promising for CO2 capture, raising the need for its sustainable production. The life cycle assessment (LCA) of various ZIF-8 synthesis methods such as solvothermal (DMF), solvothermal (MeOH), microwave, sonochemical, mechanochemical, dry-gel conversion and aqueous system was investigated. The findings indicated that the seven production methods have the highest impact on marine ecotoxicity, followed by human toxicity non-carcinogenic, and terrestrial ecotoxicity among the 18 categories of evaluation studies. The main contributor towards environmental degradation was the solvent for washing, N, N-dimethylformamide (DMF) in most of the methods. It is also revealed that replacing the solvent of DMF with methanol remarkably reduced the influence on human health, ecosystem and resources in the solvothermal (MeOH) method as compared to the solvothermal (DMF) method. As a whole, the mechanochemical method has the least impact on the environment because it has fewer production steps and is easy to operate. Therefore, this work delineates comprehensive environmental influences of different ZIF-8 synthesis methods to lay the groundwork for its mass and sustainable production.

Surfactant regulated synthesis of ZIF-8 crystals as carbonic anhydrase-mimicking nanozyme

Zeolitic imidazolate framework-8 (ZIF-8) nanozymes were successfully synthesized by using non-ionic surfactant Triton X-100 as regulator. The surfactant molecules can bind on ZIF-8 surface to modulate the nucleation and facet growth, which therefore produces ZIF-8 crystals with controlled morphology and size. The as-prepared ZIF-8 crystals reproduce the functional property of natural carbonic anhydrase (CA) by showing excellent CA-like esterase activity. The catalytic activity of ZIF-8 nanozymes was greatly enhanced at high temperature, which is superior to natural CA and is of great potential for practical applications. Moreover, the esterase activity of ZIF-8 shows great dependence on the crystal size. Basically, smaller ZIF-8 nanozymes had higher catalytic activity at a specified temperature, except for the smallest ZIF-8 crystals with size of ~50 nm that gave reduced activity due to aggregation at high temperatures of 60 or 80 °C. In addition, colorimetric experiments showed that ZIF-8 nanozymes showed similar hydration activity to that of natural CA. The study probes into the effect of nonionic surfactant on ZIF-8 synthesis as well as the abnormal size effect at higher temperature, which is of great help for the development of suitable nano-enzymes for industry applications.