Zeolitic Imidazolate Framework-8 Nanoparticles Research Articles

ZIF-8 channeled and coordination-bridging two-dimensional WS2 membrane for efficient organic solvent nanofiltration

Zeolitic imidazolate framework-8 (ZIF-8)/WS2 composite 2D membranes were constructed by in-situ growth of ZIF-8 in the interlayer of WS2 laminar membrane. The growth of ZIF-8 nanoparticles in WS2 membrane expanded the interlayer spacing, and endowed WS2 membrane with fixed interlayer spacing by coordination-bridges between WS2 and ZIF-8, which made ZIF-8/WS2 membrane possess not only high solvent permeance but also excellent stability in organic solvents. Isopropanol (IPA) permeance through ZIF-8/WS2 membrane reached 272 L/m2·h·bar, which was about 1.6 times higher than that through pristine WS2 membrane, and the rejection rates for Direct Black 38 (DB38), Congo Red (CR) and Rose Bengal (RosB) were 99%, 99% and 30% respectively. Furthermore, the IPA permeance through ZIF-8/WS2 membrane was almost unchanged after soaking in IPA for 192 h, and IPA permeance and rejection rate for DB 38 changed slightly during 100 h of cross-flow filtration, demonstrating remarkable stability of ZIF-8/WS2 membranes in organic solvents and a promising application potential in organic solvent nanofiltration.

ZIF-8 modified multifunctional injectable photopolymerizable GelMA hydrogel for the treatment of periodontitis

Periodontitis is a chronic inflammatory disease caused by plaque that leads to alveolar bone resorption. In the treatment of periodontitis, it is necessary to reduce the bacterial load and promote alveolar bone regeneration. In this study, zeolitic imidazolate framework-8 (ZIF-8) is used in the treatment of periodontitis, and an injectable photopolymerizable ZIF-8/gelatin methacryloyl (GelMA) composite hydrogel (GelMA-Z) is constructed. We confirm that ZIF-8 nanoparticles are successfully loaded into GelMA, which demonstrates fluidity and photopolymerizability. GelMA-Z continuously releases Zn2+ and shows good cytocompatibility. In vitro, GelMA-Z can effectively upregulate the expression of osteogenesis-related genes and proteins, increase alkaline phosphatase activity, promote extracellular matrix mineralization by rat bone mesenchymal stem cells, and exert an obvious antibacterial effect against Porphyromonas gingivalis. In vivo, GelMA-Z reduces the bacterial load, relieves inflammation and promotes alveolar bone regeneration in a rat model. The above results show that GelMA-Z has potential prospects in the treatment of periodontitis. Statement of significanceVarious methods have been explored for the treatment of periodontitis. However, current regiments have difficulty achieving ideal alveolar bone regeneration. In this study, we constructed a zeolitic imidazolate framework-8 (ZIF-8)/gelatin methacryloyl (GelMA) composite hydrogel (GelMA-Z). (1) The injectable and photopolymerizable GelMA-Z showed biocompatibility in vitro and in vivo. (2) GelMA-Z continually released zinc ions to promote the osteogenic differentiation of bone mesenchymal stem cells and kill bacteria in vitro. (3) In a rat model, the GelMA-Z pregel solution was used to fill the periodontal pocket and then crosslinked by UV exposure. GelMA-Z can stably remain in the periodontal pocket to reduce the bacterial load, relieve inflammation and promote alveolar bone regeneration. In conclusion, GelMA-Z has great potential for use in the treatment of periodontitis, especially in promoting alveolar bone regeneration.

Biomineralized Zeolitic Imidazolate Framework-8 Nanoparticles Enable Polymerase-Driven DNA Biocomputing for Reliable Cell Identification.

Investigating multiple miRNA expression patterns in living cells by DNA logic biocomputing is a valuable strategy for diagnosis and biomedical studies. The introduction of protein enzymes in DNA logic biocomputing circuits not only expands the toolbox of nucleic acid assembly techniques, but also further improves the specificity of recognizing and processing of DNA input. Herein, a polymerase-driven primer exchange reaction, acting as the sensing module, is introduced into the biocomputing system and transduces the multiple miRNAs sensing event into the intermediate triggers for activating the subsequent processing module, which further performs signal readout through DNAzyme catalytic substrate cleavage reaction. By using biomineralized zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs) to deliver all the components of the biocomputing system, including polymerase and DNA probes, we realized polymerase-driven DNA biocomputing operations in living cells, including AND and OR gates. The results exhibited that biomineralized ZIF-8 NPs can protect the loaded cargoes against the external environment and deliver them efficiently to the cytoplasm. The polymerase-driven DNA biocomputing system based on multiple miRNAs sensing can be used for reliable cell identification and may provide a promising platform for more accurate diagnosis and programmable therapeutics.

Heterostructured ZIF-8/lamellar talc composites incorporated polydimethylsiloxane membrane with enhanced separation performance for butanol recovery

In this study, heterostructured MOF/lamellar talc composites was successfully synthesized by in-situ growth of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles on acidified black talc (ABT) and introduced into polydimethylsiloxane (PDMS) matrix to prepare high-performance mixed matrix membranes (MMMs) via spin coating and thermal cross-linking. The submicron-size natural lamellar black talc (BT) was first explored as stable carrier to synthesize laminated composite with continuous MOF phase. Owing to its silica-oxygen tetrahedral structure, the resultant laminated composite presented good compatibility with PDMS matrix, avoiding the formation of interfacial defect between polymer and nanoparticles. Moreover, well-dispersed and continuous ZIF-8 nanoparticles on lamellar nanosheets had preferential adsorption effect for alcohol, enhancing the selectivity of membranes. The coupling effects of graphene-like lamellar structure from talc and sequential transport channels from ZIF-8 attributed to greatly enhance permeation flux. Various techniques such as FESEM, TEM, FTIR, XRD and EDS were applied to investigate the morphology and structure of composites and membranes, and pervaporation experiments were applied to probe the behavior of polymer-based composite membranes. High performance defect-free ZIF-8@ABT/PDMS MMMs exhibited excellent total permeate flux of 1711 g m−2 h−1 with very competitive separation factor of 41 for low concentration n-butanol recovery.

Synergistic modification of ZIF and silica on carbon spheres to enhance the flame retardancy of composites coatings

Herein, carbon spheres (CS) were obtained by a simple hydrothermal reaction using glucose as the raw material, which can be used as a green, cost-effective inorganic flame retardant. Then, the zeolitic imidazolate framework-8 (ZIF) nanoparticles were uniformly anchored on the surface of the CS, which could promote the formation of carbon residues, while the release of inert gas could reduce the substrate surface temperature, thereby delaying the combustion reaction. In addition, the SiO2 film was coated on the surface of ZIF-loaded CS (CS/ZIF) to fill the micropores left by thermal decomposition of ZIF nanoparticles. More importantly, the residual SiO2 shell after combustion can effectively improve the barrier effect of char layer on flame and heat. The effect of the obtained CS/ZIF@SiO2 hybrids on the fire performance of epoxy resins was characterized by fire performance tests. The experimental results showed that the backside temperature of the CS/ZIF@SiO2 based composite coating was stabilized at the lowest value (173.6 ℃) due to the combined effect of ZIF nanoparticles and silica film. In addition, the CS/ZIF@SiO2/EP showed the maximum expansion height and expansion rate after burning in a muffle furnace for 60 min. Meanwhile, the composite coating exhibited the maximum residual carbon (29.1%) and thermal decomposition temperature (Tmax, 378.1 ℃). The results of smoke density test proved that the composite coating had higher smoke suppression effect compared with other samples.

Stabilize thin nanoparticle layer of zeolitic imidazole framework-8 (ZIF-8) on different PVDF substrates by contra-diffusion method for high-efficiency ultrafiltration application

In this research, a contra-diffusion cell, which is an effective instrument for growing inorganic layers on porous substrates, was applied to prepare a thin layer of zeolitic imidazole framework-8 (ZIF-8) on polyvinylidene fluoride (PVDF) ultrafiltration membranes. With using of methanol as a solvent, a thin layer of ZIF-8 was fabricated resulted in a flexible inorganic coated organic membrane. The ZIF-8 nanoparticles were formed as a resistant layer on the outer surface and inner pores of PVDF support and its effect on permeability, flux recovery ratio (FRR) and treatment of colored wastewater was investigated. Manufacturing parameters such as the reaction time between Zn2+ ions and imidazole ligands (16, 24 and 36 h) and concentration of PVDF in the casting solution of the support membranes (18, 20 and 22 wt%) were considered. The SEM images showed the well-growing of uniform and a thin layer of ZIF-8. The membrane performance tests revealed that ZIF-8 decorated membranes have higher pure water flux, BSA protein rejection and FRR related to the uncoated PVDF membrane. The fabricated membranes indicated high removal efficiency in three different MW dyes (Rhodamine B, Reactive Green 19 and Direct Black 38), with 75, 85 and 98% rejection, respectively.

ZIF-8 Nanoparticles Based Electrochemical Sensor for Non-Enzymatic Creatinine Detection.

There is a consistent demand for developing highly sensitive, stable, cost-effective, and easy-to-fabricate creatinine sensors as creatinine is a reliable indicator of kidney and muscle-related disorders. Herein, we reported a highly sensitive and selective non-enzymatic electrochemical creatinine sensor via modifying poly(3,4 ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) coated indium tin oxide (ITO) substrate by zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs). The topography, crystallinity, and composition of the sensing electrode were characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The peroxidase-like activity of ZIF-8 nanoparticles enabled it to detect creatinine forming a zinc-creatinine composite. The electrochemical behavior and sensing performance were evaluated by amperometric and impedimetric analysis. The sensor obtained a sufficiently low limit of detection (LOD) of 30 µM in a clinically acceptable linear range (0.05 mM–2.5 mM). The interference study demonstrated high selectivity of the sensor for creatinine concerning other similar biomolecules. The sensing performance of the creatinine sensor was verified in the actual human serum, which showed excellent recovery rates. Hence, the magnificent performance of ZIF-8 based non-enzymatic creatinine sensor validated it as a responsible entity for other complicated renal markers detection.

Desalination Characteristics of Cellulose Acetate FO Membrane Incorporated with ZIF-8 Nanoparticles

Forward osmosis membranes have a wide range of applications in the field of water treatment. However, the application of seawater desalination is restricted, so the research of forward osmosis membranes for seawater desalination poses new challenges. In this study, zeolitic imidazolate framework-8 (ZIF-8) was synthesized by a mechanical stirring method, and its crystal structure, surface morphology, functional group characteristics, thermochemical stability, pore size distribution and specific surface area were analyzed. The cellulose acetate (CA)/ZIF-8 mixed matrix forward osmosis membrane was prepared by using the synthesized ZIF-8 as a modified additive. The effects of the additive ZIF-8 content, coagulation bath temperature, mixing temperature and heat treatment temperature on the properties of the CA/ZIF-8 forward osmosis membrane were systematically studied, and the causes were analyzed to determine the best membrane preparation parameters. The structure of the CA membrane and CA/ZIF-8 mixed matrix forward osmosis membranes prepared under the optimal conditions were characterized by Fourier Transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), contact angle and Atomic force microscope (AFM). Finally, the properties of the HTI membrane (Membrane manufactured by Hydration Technology Innovations Inc.), CA forward osmosis membrane and CA/ZIF-8 mixed matrix forward osmosis membrane were compared under laboratory conditions. For the CA membrane, the water flux and reverse salt flux reached 48.85 L·m−2·h−1 and 3.4 g·m−2·h−1, respectively. The reverse salt flux and water flux of the CA/ZIF-8 membrane are 2.84 g·m−2·h−1 and 50.14 L·m−2·h−1, respectively. ZIF-8 has a promising application in seawater desalination.

Augmented EPR effect post IRFA to enhance the therapeutic efficacy of arsenic loaded ZIF-8 nanoparticles on residual HCC progression

BackgroundInsufficient radiofrequency ablation (IRFA) can promote the local recurrence and distal metastasis of residual hepatocellular carcinoma (HCC), which makes clinical treatment extremely challenging. In this study, the malignant transition of residual tumors after IRFA was explored. Then, arsenic-loaded zeolitic imidazolate framework-8 nanoparticles (As@ZIF-8 NPs) were constructed, and their therapeutic effect on residual tumors was studied.ResultsOur data showed that IRFA can dramatically promote the proliferation, induce the metastasis, activate the epithelial–mesenchymal transition (EMT) and accelerate the angiogenesis of residual tumors. Interestingly, we found, for the first time, that extensive angiogenesis after IRFA can augment the enhanced permeability and retention (EPR) effect and enhance the enrichment of ZIF-8 nanocarriers in residual tumors. Encouraged by this unique finding, we successfully prepared As@ZIF-8 NPs with good biocompatibility and confirmed that they were more effective than free arsenic trioxide (ATO) in sublethal heat-induced cell proliferation suppression, apoptosis induction, cell migration and invasion inhibition, and EMT reversal in vitro. Furthermore, compared with free ATO, As@ZIF-8 NPs exhibited remarkably increased therapeutic effects by repressing residual tumor growth and metastasis in vivo.ConclusionsThis work provides a new paradigm for the treatment of residual HCC after IRFA.Graphical

Tough ion gels composed of coordinatively crosslinked polymer networks using ZIF-8 nanoparticles as multifunctional crosslinkers.

Constructing crosslinked polymer networks via reversible interactions is a promising approach to recover the mechanical strength of damaged gels. In addition, by designing effective reversible crosslinks, the mechanical strength of the gel can be enhanced through energy dissipation based on the destruction of the crosslinks by an applied force. In this study, we introduced zeolitic imidazole framework-8 nanoparticles (ZIF-8 NPs), which acted as multifunctional crosslinkers, to provide multipoint coordination bonding with a poly(N,N-dimethylacrylamide)-based polymer network in a gel containing an ionic liquid. The mechanical strength of the gel increased with an increase in the content of ZIF-8 NPs up to 6 wt%. It was confirmed that the energy loaded onto the gel was dissipated through the desorption of the polymer network from the surface of the ZIF-8 NPs. Owing to the reversible destruction and reconstruction of the coordinative crosslinking between the polymer network and ZIF-8 NPs, the mechanical strength of the damaged gel was almost fully recovered through annealing.

Targeted therapy of atherosclerosis by zeolitic imidazolate framework-8 nanoparticles loaded with losartan potassium via simultaneous lipid-scavenging and anti-inflammation.

Atherosclerosis (AS) is a condition associated with dysfunctional lipid metabolism and an inflammatory immune microenvironment that remains the leading cause of severe cardiovascular events. Drugs exhibiting both anti-inflammatory and lipid-scavenging activity hold great promise for treating AS. In this study, zeolitic imidazolate framework-8 (ZIF-8) nanoparticles loaded with losartan potassium (LP) were developed as an anti-AS treatment to target both of these therapeutic arms simultaneously. LP@ZIF-8 accumulated within AS target tissues via the enhanced permeability and retention (EPR) effect, as confirmed via in vivo near-infrared fluorescence (NIRF) imaging and wasdisruptedin response tothe low pH. ZIF-8 could activate autophagy, thus regulatinglipid metabolism and restoringcholesterol homeostasis aspreviously reported, while thereleasedLPservedas an anti-inflammatory angiotensin receptor blocker (ARB) inhibitor, which was confirmed via the in vivo treatment studies. As such, our data highlight LP@ZIF-8 as a promising therapeutic agent capable of attenuating the severity of AS.

Curcumin doped zeolitic imidazolate framework nanoplatforms as multifunctional nanocarriers for tumor chemo/immunotherapy.

Curcumin as a hydrophobic polyphenol has great potential for tumor therapy, yet its rapid degradation and hydrophobicity severely impair its therapeutic effect in the clinic. Herein, we report a novel strategy for the formation of curcumin doped zeolitic imidazolate framework nanoparticles (Cur-ZIF NPs) by zinc ion driven simultaneous coordination of curcumin and 2-methylimidazole. The resultant Cur-ZIF NPs with a uniform nanosize exhibit favorable stability and dispersibility in water, as well as high drug-loading capacities. The pH and redox sensitivity of ZIF NPs enable the controlled release of curcumin in vivo. Moreover, Cur-ZIF NPs serve as nanocarriers that can load the toll-like-receptor-7 agonist (imiquimod, IQ) and be coated by homotypic cancer cell membranes to enhance tumor-targeted delivery. This study provides an attractive nanoplatform to effectively utilize curcumin and integrate multiple therapeutic modalities into a single system for tumor treatment.

De novo synthesis of amino-functionalized ZIF-8 nanoparticles: Enhanced interfacial compatibility and pervaporation performance in mixed matrix membranes applying for ethanol dehydration

The incorporation of attainable amine functionality in zeolitic imidazolate framework-8 (ZIF-8) is utilized to enhance the pervaporation performance for ethanol/ water separation applications. Using 2-aminobenzimidazole, a ligand with NH2-functionalized group, displacement of the ZIF-8 original ligand during de novo synthesis while preserving the ZIF-8 initial structure, which produces a novel mixed- linker ZIF material (ZIF-8-NH2) with smaller nanocrystal size, controllable pore size, and enhanced hydrophilicity. A series of different mixed matrix membranes (MMMs) were fabricated by incorporating ZIF-8-NH2 into poly(vinyl alcohol) (PVA) matrix. Various characterization techniques, such as FTIR, 1H NMR, XRD, SEM, TGA, and Contact angle etc. were employed to demonstrate the properties of prepared ZIF nanoparticles and the MMMs. The results indicated that ZIF-8-NH2 and the MMMs were perfectly fabricated, which were attributed to better dispersion and compatibility between them. In particular, 7-ZIF-8-NH2/PVA MMM exhibited a comparable total flux of 142 g/m2·h and water/ethanol separation factor of 925, which were increased by 73 and 524%, on the basis of the pristine PVA membrane. In addition, different nanofillers, APTES crosslinking, ZIF-8-NH2 loading, operating temperature, feed concentration, and membrane stability were evaluated in detail. This study might provide a promising prospect for designing MOF-based MMMs with the introduction of various functional groups.

An electrostatic repulsion strategy construct ZIFs based liquids with permanent porosity for efficient CO2 capture

Porous liquids (PLs), as a novel liquid sorbent with permanent porosity, still present challenges such as high viscosity and melting temperatures. Herein, an efficient electrostatic repulsion strategy is proposed to engineer zeolitic imidazolate frameworks (ZIFs) type III PLs employing ZIF-8-g-BPEI nanoparticle stability dispersed into BPEI. The viscosity and melting temperatures of ZIF-8-g-BPEI PLs could be tailored via control particle size, grafting polymer, and concentration of porous nanoparticles. The existence of BPEI on the surface of ZIF-8-g-BPEI facilitates the stable dispersion of ZIFs nanoparticles in BPEI via the electrostatic repulsion as well as enhances CO2 adsorption capacity of PLs. Moreover, the CO2 adsorption amount of ZIF-8-g-BPEI-30 PLs is 6.5 times high than that of neat BPEI, suggesting the permanent free volume of ZIFs is retained in their corresponding PLs. Benefiting from the branched structure of BPEI grafted onto the outer surface of ZIFs , ZIF-8-g-BPEI-10 PLs remain liquified down to -71.1 °C, together with viscosity as 1.7 Pa·s−1 at 25 °C. Therefore, the electrostatic repulsion strategy opens an effective avenue to prepare novel liquid materials and shows numerous potential applications in gas adsorption and separation.

Facile preparation of nanocellulose/Zn-MOF-based catalytic filter for water purification by oxidation process

Sulfate radical (SO4•-)-based advanced oxidation processes (SR-AOPs) have recently attracted much attention due to their potential in degrading organic pollutants. Metal-organic frameworks (MOFs) have been reported as effective materials to generate SO4•-. However, it is challenging to separate and recover the dispersed MOF particles from the reaction solution when MOFs are used alone. We used cellulose nanofibers (CNFs) as a porous filter template to immobilize Zn-based MOF, zeolitic imidazolate framework-8 (ZIF-8), and obtained a catalytic composite membrane having peroxymonosulfate (PMS) activating function to produce SO4•-. The CNF was effective in holding ZIF-8 nanoparticle and making a durable porous filter. The activated PMS-produced •OH and SO4•- radicals from ZIF-8 play an important role in the catalytic reaction. More than 90% of methylene blue and rhodamine B was degraded by ZIF-8/CNFs composite membrane in the PMS environment within 60min. The ZIF-8/CNFs catalytic filters can be used several times without performance reduction for organic dye degradation. The results show that ZIF-8/CNFs catalytic membrane can be separated from organic pollution system quickly and used for the efficient separation and recovery of MOF particle-based catalytic materials. Therefore, this study provides a new perspective for fabricating the MOFs particles-immobilized catalytic filter by biomass nanocellulose-based materials for water purification. This method can be used for facile fabrication of the cellulose-based porous functional filter and open diverse applications.

Folic Acid-Modified miR-491-5p-Loaded ZIF-8 Nanoparticles Inhibit Castration-Resistant Prostate Cancer by Regulating the Expression of EPHX1.

Epoxide hydrolase 1 (EPHX1) has been reported to be related to the development of several tumors. However, the regulation of castration-resistant prostate cancer (CRPC) development by EPHX1 has not been reported. We used proteomic technology and found that the EPHX1 protein was highly expressed in CRPC tissues and the CRPC cell line C4-2. We performed screening and found that EPHX1 is a direct target of miR-491-5p. High miR-491-5p expression significantly reduced the EPHX1 level in C4-2 cells and inhibited C4-2 cell proliferation and migration. Zeolite imidazolate framework-8 (ZIF-8) has good thermal stability, a simple synthesis method, tumor site stability, and specific acid responsiveness. We synthesized ZIF-8 nanodrug vectors to deliver miR-491-5p into C4-2 cells. After loading miR-491-5p into ZIF-8, we modified the ZIF-8 surface with folic acid (FA) as the target group (FA@ZIF-8). Our synthesized nanodrug carrier showed less cytotoxicity to C4-2 cells even at 200 μg/ml. Modified FA could increase the efficiency of nanomaterial entry into C4-2 cells. FA@miR-491-5p@ZIF-8 could stably release miR-491-5p for a long period in both phosphate-buffered saline (pH 7.4) and acetate buffer (pH 4.8), and miR-491-5p was released faster at the beginning of the experiment in acetate buffer (pH 4.8). FA@miR-491-5p@ZIF-8 significantly reduced C4-2 cell proliferation and migration, and FA@miR-491-5p@ZIF-8 had a better effect than miR-491-5p alone. In vivo, FA@miR-491-5p@ZIF-8 significantly inhibited CRPC growth in nude mice. Overall, we verified that miR-491-4p regulated CRPC development by targeting EPHX1. The drug nanocarrier FA@miR-491-5p@ZIF-8 not only significantly reduced C4-2 CRPC cell proliferation and migration but also significantly inhibited CRPC growth. Our research provides a theoretical basis for treatment and treatment strategies for CRPC.

Hydrostable ZIF-8 layer on polyacrylonitrile membrane for efficient treatment of oilfield produced water

The treatment and reclamation of oilfield produced water by membrane technology is severely limited by fouling. Zeolitic imidazole framework-8 (ZIF-8) nanoparticles are promising functional materials for antifouling membrane modifications. However, their limited stability as a separating layer during filtration is a major challenge. Here, we describe a facile route for chemical stabilization of the ZIF-8 layer on a polyacrylonitrile membrane using a redox-grafted zwitterionic methacrylate hydrogel. Microscopic and spectroscopic techniques confirmed the structure and stability of the ZIF-8/methacrylate hydrogel layer. Furthermore, no detectable ZIF-8 particles leached out from the modified membrane during filtration experiments. The hydrostability is achieved via coordination interactions between the negatively charged sulfonate groups of the hydrogel and the positively charged ZIF-8 nanoparticles. Compared to the pristine membrane, the modified membrane showed higher hydrophilicity, lower surface roughness, and its pure water permeance was ∼13% higher. Treatment of simulated oilfield produced water by the membranes for three 4-h filtration cycles showed that the modified membrane exhibited exceptionally high antifouling properties compared to the pristine membrane (flux recovery ratio of 98.5 ± 0.6% vs. 8.1 ± 0.7%) and showed 99.7 ± 0.3% oil rejection efficiency. In a longer treatment duration, after 10 filtration cycles for 42 h, the modified membrane showed a flux recovery ratio of 90.3% and oil rejection efficiency >99%, indicating its outstanding performance for oilfield produced water treatment. Thus, our membrane with a hydrostable ZIF-8 layer holds excellent promise for produced water treatment applications.

Advantages of polydopamine coating in the design of ZIF-8-filled thin-film nanocomposite (TFN) membranes for desalination

In this study, zeolitic imidazolate framework-8 (ZIF-8) nanoparticles coated with polydopamine (PDA) were synthesized and used to prepare thin film nanocomposite (TFN) membranes for desalination. Structures, properties, and desalination performances of the membranes were systematically compared with those of membranes containing unmodified ZIF-8 nanoparticles or not containing ZIF-8, revealing the significance of the PDA coating on the overall performance of the TFN membranes. The PDA coating provided ZIF-8 nanoparticles with dispersibility in water and resistance to hydrochloric acid as a by-product of interfacial polymerization, which allowed them to be uniformly dispersed in the selective layer without agglomeration and deterioration of the crystalline structure. These are very important for the improvement of the permeability and stability of TFN membranes while maintaining the selectivity. In addition, the PDA coating inhibited the direct contact of ZIF-8 with an organic foulant, which dramatically enhanced the fouling resistance of the membranes.

Monodisperse ZIF-8@dextran nanoparticles co-loaded with hydrophilic and hydrophobic functional cargos for combined near-infrared fluorescence imaging and photothermal therapy

Impressive developments have been achieved with the use of zeolitic imidazolate framework-8 (ZIF-8) as nanocarriers for tumor theranostics in recent decades by incorporating imaging agents and therapeutic drugs within ZIF-8. However, the simultaneous immobilization of hydrophilic and hydrophobic functional molecules into ZIF-8 nanoparticles in water or organic solvents still presents a daunting challenge. Herein, we developed a new synthesis/encapsulation two-in-one (denoted as one-pot) approach to synthesize uniform dextran-modified Cy5.5&ICG@ZIF-8-Dex nanoparticles in DMSO/H2O solvent mixtures, which enabled the simultaneous encapsulation of hydrophilic indocyanine green (ICG) and hydrophobic cyanine-5.5 (Cy5.5) during the same step. It was confirmed that the one-pot approach in this mixed solvents facilitated the loading of ICG and Cy5.5 molecules. Moreover, the encapsulation of Cy5.5 and ICG within ZIF-8 nanoparticles endowed them with fluorescence imaging capability and photothermal conversion capacity, respectively. The in vivo near-infrared (NIR) fluorescent images of A549-bearing mice injected with Cy5.5&ICG@ZIF-8-Dex demonstrated sufficient accumulations of Cy5.5 at tumor sites due to the enhanced permeability and retention effect. Most impressively, the fluorescent intensity of Cy5.5&ICG@ZIF-8-Dex at tumor site was approximately 40-fold higher than that of free Cy5.5. Additionally, the results of in vivo infrared imaging and photothermal therapy of Cy5.5&ICG@ZIF-8-Dex showed enhanced therapeutic efficiency in comparison with free ICG, further confirming its tumor-targeting capability and photothermal capacity. Therefore, this multifunctional system based on ZIF-8 nanocarriers offered a potential nanoplatform for tumor-targeting theranostics, thus broadening the synthesis and applications of ZIF-8 composite nanoparticles for NIR fluorescence imaging and photothermal therapy in the biomedical field. Statement of significanceSimultaneous immobilization of hydrophilic and hydrophobic molecules into ZIF-8 nanoparticles still remains a daunting challenge. Therefore, we have developed a new synthesis/encapsulation two-in-one approach to synthesize uniform Cy5.5&ICG@ZIF-8-Dex composite nanoparticles in DMSO/H2O solvent mixtures, which enabled the simultaneous encapsulation of hydrophilic indocyanine green (ICG) and hydrophobic cyanine-5.5 (Cy5.5) functional molecules during a single step. The results showed that the co-loading of Cy5.5 and ICG within the ZIF-8 nanoparticles endowed them with a remarkable fluorescence imaging capability and photothermal conversion capacity. Based on their enhanced convenience and efficacy to simultaneously encapsulate hydrophilic and hydrophobic molecules, the multifunctional nanocarriers that were prepared in the DMSO/H2O mixed solvents provide a potential nanoplatform toward fluorescence imaging and photothermal therapy for tumor theranostics.

Enhancement of proton conductivity of crosslinked poly(vinyl alcohol) through introduction of zeolitic imidazolate framework-8 and imidazole

Proton exchange membranes from crosslinked poly(vinyl alcohol) using sulfosuccinic acid (SSA) and glutaraldehyde as double crosslinking agents were reported. The effect of SSA content on water uptake and proton conductivity was investigated. The most promising membrane was then formed into composites with zeolitic imidazolate framework-8 (ZIF-8). ZIF-8 was synthesized, and confirmed by Fourier transform infrared spectroscopy, X-ray diffraction analysis, and transmission electron microscopy. The effect of ZIF-8 loading (0–10%) on membrane properties was firstly reported. Relatively good dispersion of ZIF-8 nanoparticles was observed for composites with %loadings up to 5%. The enhancements in proton conductivity and mechanical strength were observed upon ZIF-8 addition, and the optimum loading was 5%. In an attempt to improve proton conductivity at low relative humidity, the composite was further doped with imidazole. Proton conductivity increased with increasing imidazole content and temperature, and reached a maximum of 2.3 × 10−4 S/cm at 80 °C under non-humidified condition.