Fabrication of natural enzyme-covered / amino-modified Pd-Pt bimetallic-doped zeolitic imidazolate framework for ultrasensitive detection of metabolites.

The present article introduced an natural enzyme-covered/amino-modified Pd-Pt bimetallic-doped zeolitic imidazolate framework (NAPPZ) for ultrasensitive and specific detection of glucose. The dodecahedral nanomaterial zeolitic imidazolate framework (ZIF-8)-loaded Pd-Pt bimetallic nanoparticles endowed the composite with peroxidase-like activity. The modification with glucose oxidase (GOx) facilitated the rapid access of H2O2 produced through glucose oxidation to the Pd-Pt nanoparticles vicinity reducing diffusion. GOx specifically catalyzes the transformation of glucose into H2O2, which then H2O2 rapidly migrates to the Pd-Pt nanoparticles, catalyzing the oxidation of colorless o-phenylenediamine into the orange-yellow product 2,3-diaminophenazine. Based on the aforementioned cascade reaction, the NAPPZ and NAPPZ based on ChOx were utilized for detecting glucose in human urine samples and cholesterol in milk, respectively. The NAPPZ strategy presented a broad detection range (20-1100 µmol L-1) and a low detection limit (15.9 µmol L-1) for glucose, and the NAPPZ based on ChOx strategy approach offered a broad detection range (10-500 µmol L-1) and low detection limit (6.4 µmol L-1) for cholesterol. Therefore, this novel method holds significant potential in the areas of clinical diagnostics and food safety.

Porous titanium scaffolds modified with Zeolitic Imidazolate Framework (ZIF-8) with enhanced osteogenic activity for the prevention of implant-associated infections.

In this study, zeolitic imidazolate framework 8 (ZIF-8) was coated on porous Ti6Al4V scaffolds, either bare or previously modified using hydroxyapatite (HA) or HA and gelatin (HAgel), via a growing single-step method in aqueous media using two contact times at 6 h and 24 h. The coated scaffolds termed ZIF-8@Ti, ZIF-8@HA/Ti, and ZIF-8@HAgel/Ti were characterized via scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and molecular plasma-atomic emission spectroscopy (MP-AES). In order to assess the cell proliferation rate, the cytocompatibility of the scaffolds was evaluated in primary osteoblasts (hOBs) using alamarBlue assay, while the osteoconductivity was analyzed in hOBs using a real-time approach, evaluating the expression of secreted phosphoprotein 1 (SPP1). Osteopontin, which is the protein encoded by this gene, represents the major non-collagenous bone protein that binds tightly to HA. The scaffolds were shown to be non-cytotoxic based on hOB proliferation at all time points of analysis (24 h and 72 h). In hOB cultures, the scaffolds induced the upregulation of SPP1 with different fold changes. Some selected scaffolds were assayed in vitro for their antibacterial potential against Staphylococcus epidermidis; the scaffolds coated with ZIF-8 crystals, regardless of the presence of HA and gelatin, strongly inhibited bacterial adhesion to the materials and reduced bacterial proliferation in the culture medium, demonstrating the suitable release of ZIF-8 in a bioactive form. These experiments suggest that the innovative scaffolds, tested herein, provide a good microenvironment for hOB adhesion, viability, and osteoconduction with effective prevention of S. epidermidis adhesion.

Synergistic Photothermal Tumor Immunotherapy by 1-MT Based on Zeolitic Imidazolate Framework-8 with pH-High Sensitivity.

Background: A successful immune response against tumors depends on various cellular processes. Hence, there is an urgent need to construct a proficient nanoplatform for immunotherapy that can concurrently regulate the activities of various cells participating in the immune process. We have developed zeolitic imidazolate framework-8 (ZIF-8) formula, with good pH sensitivity, which is conducive to the release of drugs in the tumor site (acidic environment) and significantly improves immunotherapy. This is achieved through the coordinated action of different therapeutic agents, such as the photothermal agent polydopamine (PDA), the chemodrug camptothecin (CPT), and the immunomodulator 1-methyl-D-tryptophan (1-MT). Materials and Methods: In this study, we evaluated the antitumor effect of PDA/(CPT + 1-MT) @ZIF-8 (PCMZ) nanoparticles (NPs) in vitro and in vivo and investigated the molecular mechanism of PCMZ NPs in tumor suppression via photothermal-chemo-immunotherapy. Results: MTT and Annexin V-FITC/PI double staining apoptosis test showed that PCMZ NPs could induce apoptosis of 4T1 cell, and PCMZ NPs could cause 4T1 cell necrosis under 808 nm laser irradiation. The objective is to establish a unilateral breast cancer model in mice and investigate the effect of PCMZ NPs on tumor growth and tumor suppression in tumor bearing mice. The results showed that PCMZ NPs showed good heating effect in vivo and effectively inhibited tumor growth under 808 nm laser irradiation. In addition, PCMZ NPs could induce the immunogenic death of tumor cells, promote the maturation of DCs, inhibit IDO pathway, and finally differentiate T cells into cytotoxic T cells and helper T cells, so as to effectively activate the anti-tumor immune response. Conclusion: The PCMZ NPs, possessing good photothermal conversion capabilities due to join of PDA, effectively overcome two main challenges in immunotherapy: insufficient stimulation of the immune response and evasion of the immune system. This provides a robust platform against invasive cancer and recurrent tumors.

Integrating sodium cholate-modified MOF hybrid lipase and solubilization of hydrophobic candidates into a step for liganding fishing lipase inhibitors from Nelumbinis Folium.

Enzyme immobilization by metal organic frameworks (MOFs) is an efficient way for screening active constituents in natural products. However, the enzyme's biocatalysis activity is usually decreased due to unfavorable conformational changes during the immobilization process. In this study, sodium cholate was firstly used as the modifier for zeolitic imidazolate framework-8 (ZIF-8) immobilized lipase to increase both the stability and activity. More importantly, with the help of solubilization of sodium cholate, a total of 3 flavonoids and 6 alkaloids candidate compounds were fished out. Their structures were identified and the enzyme inhibitory activities were verified. In addition, the binding information between the candidate compound and the enzyme was displayed by molecular docking. This study provides valuable information for the improvement of immobilized enzyme activity and functional active ingredients in complicated medicinal plant extracts.

ZIF-8-modified hydrogel sequentially delivers angiogenic and osteogenic growth factors to accelerate vascularized bone regeneration.

To realize high-quality vascularized bone regeneration, we developed a multifunctional hydrogel (SHPP-ZB) by incorporating BMP-2@ZIF-8/PEG-NH2 nanoparticles (NPs) into a sodium alginate/hydroxyapatite/polyvinyl alcohol hydrogel loaded with PDGF-BB, allowing for the sequential release of angiogenic and osteogenic growth factors (GFs) during bone repair. ZIF-8 served as a protective host for BMP-2 from degradation, ensuring high encapsulation efficiency and long-term bioactivity. The SHPP-ZB hydrogel exhibited enhanced mechanical strength and injectability, making it suitable for complex bone defects. It provided a swelling interface for tissue interlocking and the early release of Zn2+ and tannin acid (TA) to exert antioxidant and antibacterial effects, followed by the sequential release of angiogenic and osteogenic GFs to promote high-quality vascularized bone regeneration. In vitro experiments demonstrated the superior angiogenic and osteogenic properties of SHPP-ZB compared to other groups. In vivo experiments indicated that the sequential delivery of GFs via SHPP-ZB hydrogel could improve vascularized bone regeneration. Further, RNA sequencing analysis of regenerative bone tissue revealed that SHPP-ZB hydrogel promoted vascularized bone regeneration by regulating JUN, MAPK, Wnt, and calcium signaling pathways in vivo. This study presented a promising approach for efficient vascularized bone regeneration in large-scale bone defects.

Synthesis of metal framework-modified carbon dots with super large stokes shift using Hami melon as a green precursor for detecting thiophanate-methyl residue in leafy vegetables.

Consuming leafy vegetables with excessive thiophanate-methyl (TM) residue poses serious risks to human health. To realize rapidly and sensitively detecting TM in leafy vegetables, we developed a fluorescent probe based on zeolitic imidazolate framework-8-modified carbon dots using Hami melon as the green precursor (HM-CDs@ZIF-8). Meanwhile, the mechanism of HM-CDs@ZIF-8 for detecting TM was investigated and explained. The results of the performance tests showed that the prepared HM-CDs@ZIF-8 exhibited high sensitivity, excellent selectivity, robust anti-interference capability, reliable reproducibility and repeatability, and long-term stability. After optimization experiments, the fluorescence intensity of HM-CDs@ZIF-8 showed a strong linear correlation with the concentration of TM (0.00171-3.4239 mol/L) with a detection limit of 2.025 µmol/L. The HM-CDs@ZIF-8 was successfully applied to determine TM in spiked leafy vegetables with satisfactory recoveries of 96-105%. The relative standard deviations were in the range of 0.26-2.55%. The sensor has a promising application for detecting TM in leafy vegetables.

A biosensor integrating the electrochemical and fluorescence strategies for detection of aflatoxin B1 based on a dual-functionalized platform.

BACKGROUND: Aflatoxin B1 (AFB1), is a potent hepatic carcinogen which causes cancer by inducing DNA changes in the liver cells. Variety of methods have been developed for detection of AFB1 which are based on single mode detection strategy. Fabrication of novel platform which are compatible for multimodal detection of AFB1 provide robust performance for reliable detection of AFB1. In this study, we aimed to develop a robust biosensing platform that combines electrochemical and fluorescence techniques for the sensitive and specific detection of Aflatoxin B1. RESULTS: The sensing platform includes the magnetic core-shell Fe3O4@AuNPs and zeolitic imidazolate framework-8 (ZIF-8). In electrochemical mode, the applied voltametric approach was used through functionalization of glassy carbon electrode and exhibited a linear range between 0.5 and 10000 pg mL-1 with LOD of 0.32 pg mL-1. Fluorescence analysis was based on the FRET on/off status of FAM-functionalized aptamer deposited on the same platform. The FAM emission recovered by the addition of AFB1 concentration in the range of 6-60 fg mL-1 with the LOD of 0.20 fg mL-1. The real sample analysis demonstrated satisfactory relative recoveries in the range of 92.81-105.32 % and 91.66-106.66 % using the electrochemical and fluorescence methods, respectively, and its reliability was confirmed by the HPLC technique. SIGNIFICANCE: The experimental results affirm that the proposed aptasensor serves as a sensitive, efficient, and precise platform for monitoring AFB1 in both electrochemical and fluorescence detection approaches. Proposed strategy showed efficient selectivity among different analytes and was reproducible. Furthermore, the applicability of biosensor was confirmed in food and biological samples.

Carbon dots encapsulated zeolitic imidazolate framework-8 as an enhanced multi-antioxidant for efficient cytoprotection to HK-2 cells.

Excessive reactive oxygen species (ROS) can lead to the imbalance of antioxidant system in the body and cause oxidative damage to cells. It is imperative to rationally design nanomaterials with high catalytic activity and multiple antioxidant activities. Here, line peppers-derived carbon dots (CDs) is encapsulated into zeolitic imidazolate framework-8 (CDs@ZIF-8) to achieve enhanced antioxidant activities for improved protective effect on cells. This nanosystem has a broad spectrum of antioxidant properties, which can effectively remove a variety of intracellular ROS and protect cells from ROS-induced death and cytoskeleton damage. In addition, CDs@ZIF-8 can reduce malondialdehyde (MDA) level and increase the enzyme activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as the level of glutathione (GSH) in human kidney proximal tubular epithelial cells (HK-2) cells. Mechanism studies demonstrated that CDs@ZIF-8 can up-regulate the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), allowing the regulation of antioxidant enzymes to further achieve antioxidant effect. Besides, CDs@ZIF-8 inhibited the secretion of proinflammatory cytokines. This work demonstrates that the constructed CDs@ZIF-8 with multi-antioxidant activity can act as a highly efficient intracellular ROS scavenger and provide potential for the application in related oxidative stress-induced diseases.

Quercetin-Loaded Zeolitic Imidazolate Framework-8 (ZIF-8) Nanoparticles Attenuate Osteoarthritis by Activating Autophagy via the Pi3k/Akt Signaling.

Osteoarthritis treatment remains a significant clinical challenge. Quercetin, a natural flavonoid with anti-inflammatory and antiapoptotic properties, might be utilized to treat OA. However, poor water solubility and short joint retention duration limit its bioavailability and translation to clinical applications. A one-step self-assembly method was utilized to fabricate quercetin-loaded zeolitic imidazolate framework-8 (Qu@ZIF-8) nanoparticles using zinc ions, 2-methylimidazole, and quercetin. In vitro tests showed that Qu@ZIF-8 nanoparticles released pH-responsive agents into chondrocytes, effectively protecting them from interleukin (IL)-induced inflammation and apoptosis, thereby promoting cartilage anabolic activities. These underlying mechanisms revealed a remarkable increase of autophagy in IL-ß-treated chondrocytes, followed by the inhibition of the Pi3k/Akt signaling pathway, which contributed to the protective effect of Qu @ZIF-8. By the establishment of medial meniscus instability (DMM) in OA mice, Qu@ZIF-8 substantially improved cartilage structural integrity and chondrocyte status, as well as attenuated OA progression. Importantly, Qu@ZIF-8 outperformed quercetin alone in the treatment of OA due to its control release. The combined research findings indicate that Qu@ZIF-8 shields chondrocytes from inflammation and apoptosis by activating autophagy and repressing the Pi3k/Akt pathway. This investigation may provide new insights for clinically extending the therapy of OA.

Grating-Integrated Gold Nanograsses Encapsulated with ZIF-8: A Quantitative and Ultrasensitive Surface-Enhanced Raman Scattering Substrate.

We proposed and demonstrated highly sensitive hybrid surface-enhanced Raman scattering (SERS) substrates, which are grating-integrated gold nanograsses (GIGN) that are tip-selectively encapsulated by ZIF-8 nanospheres (GIGN/tip-ZIF). This unique structure is realized through the tip-selective modification of GIGN by polyvinylpyrrolidone (PVP), and then, the tips of the GIGN were encapsulated by ZIF-8 nanospheres. The ZIF-8 nanospheres can adsorb analyte molecules, resulting in the spatial overlap between the analyte molecules and the "hotspots" on the tips of GIGN. Such a unique GIGN/tip-ZIF hybrid SERS substrate exhibits high sensitivity and quantitative detection ability. The detection limits can reach as low as 10-11 M, and the relative standard deviation is 5.59% for 4-aminothiophenol (4-ATP). In a wide range of concentrations from 10-5 to 10-11 M, the SERS intensity and concentration relationship can be fitted as a sigmoidal curve with R2 = 0.988. These indicate that the GIGN/tip-ZIF hybrid SERS substrates have broad applications in detecting toxic and harmful substances in food safety, disease diagnosis, and environmental monitoring.

Ratiometric fluorescent determination of sulfadimethoxine in foods based on a dual-emission metal-organic framework.

Ratiometric fluorescence detection is endowed with higher accuracy than single fluorescence signal assay. In this work, we construct a ratiometric fluorescence probe for the facile quantification of sulfadimethoxine (SDM) in foods. By wrapping N-doped carbon dots (N-CDs) and gold nanoclusters (AuNCs) into zeolitic imidazolate framework-8 (ZIF-8), the nanocomposite of N-CDs/AuNCs@ZIF-8 is facilely prepared and emits two fluorescence including 475 nm from N-CDs and 650 nm from AuNCs. Since bovine serum albumin (BSA) is the stabilizer of AuNCs, SDM can form a complex with BSA, resulting in the fluorescence quenching of AuNCs at 650 nm by a static quenching mechanism. In contrast, SDM has a rare influence on the fluorescence of N-CDs (475 nm). As a result, the use of the probe of N-CDs/AuNCs@ZIF-8 for SDM detection enables simultaneous measurement of response signal and reference signal. Under the optimal condition, the SDM assay based on the probe has a good linear relationship within 10 to 2 × 106 ng/mL and the limit of detection (LOD) is low to 1.064 ng/mL. In addition, the fluorescent probe shows good reliability for the detection of SDM in practical food samples.

Thermally Annealed High-Aspect-Ratio ZIF-8 Nanoplates-Incorporated Mixed Matrix Membranes for Improved H2/CO2 Selectivity.

The main challenge in the preparation of MOF-based mixed matrix membranes is to construct a good interface morphology to improve the gas separation performance and stability of the membranes. Herein, high-aspect-ratio ZIF-8 nanoplates for H2/CO2 separation membranes were synthesized by direct template conversion. The ZIF-8 nanoplates were prepared with the commercial Matrimid polymer to form MMMs by the flat scraping method. The homogeneous dispersion of high-aspect-ratio nanoplates in the membrane and the good compatibility between the filler and the matrix caused by the thermal annealing operation improve the gas separation performance and mechanical properties of MMMs. The H2/CO2 selectivity of MMMs loaded with 30 wt % ZIF-8 nanoplates increased to 10.3, and the H2 permeability was 330.1 Barrer. This synthesis method can be extended to prepare various ZIF nanoplates with elevated aspect ratios to obtain excellent performance fillers for gas separation of MMMs. In addition, the thermal annealing operation allows more efficient gas separation in polymer membranes and is a feasible way to design excellent and stable MMMs.

Evodiamine encapsulated by hyaluronic acid modified zeolitic imidazolate framework-8 for tumor targeted therapy.

Evodiamine (EVO), a natural bioactive compound extracted from Evodia rutaecarpa, shows therapeutic ability against malignant melanoma. However, the poor solubility and bioavailability of EVO limit its clinical application. Metal-organic frameworks (MOFs) have shown excellent physical and chemical properties and are widely used as drug delivery systems. Among them, zeolitic imidazolate framework-8 (ZIF-8) is a research popular material because of its unique properties, such as hydrothermal stability, non-toxicity, biocompatibility, and pH sensitivity. In this study, in order to load EVO, a drug carrier that hyaluronic acid (HA) modified zeolitic imidazolate framework-8 (ZIF-8) is synthesized. This drug carrier has shown drug loading with 6.2 ± 0.6%, and the nano drugs (EVO@ZIF-8/HA) have good dispersibility. Owing to the decoration HA of EVO@ZIF-8, the potential of the nano drugs is reversed from the positive charge to the negative charge, which is beneficial to blood circulation in vivo. Furthermore, because the CD44-expressing in tumor cells is excessed, the endocytosis and accumulation of nano drugs in tumor cells are beneficial to improvement. Compared with free EVO, EVO@ZIF-8/HA has shown a significantly improved anti-tumor efficacy in vitro and in vivo. In summary, the drug carrier effectively addresses the challenges that are caused by the strong hydrophobicity and low bioavailability of EVO, thereby targeted tumor therapy of EVO can be achieved.

Synthesis and Application of a pH-Responsive Functional Metal-Organic Framework: In Vitro Investigation for Delivery of Oridonin in Cancer Therapy.

Oridonin (Ori) is a naturally existing diterpenoid substance that mainly exists in the Chinese medicinal plant Rabdosia rubescens. It was previously found to possess intriguing biological properties; however, the quick clearance from plasma and limited solubility in water restricts its use as a drug. Several metal-organic frameworks (MOFs), having big surfaces and large pores, have recently been considered promising drug transporters. The zeolitic imidazolate framework-8 (ZIF-8), a form of MOF consisting of 2-methylimidazole with zinc ions, is structurally stable under physiologically neutral conditions, while it can degrade at low pH values such as in tumor cells. Herein, a nanosized drug delivery system, Ori@ZIF-8, was successfully designed for encapsulating and transporting oridonin to the tumor site. The drug loading of the prepared Ori@ZIF-8 was 26.78%, and the particles' mean size was 240.5 nm. In vitro, the release of Ori@ZIF-8 exhibited acid sensitivity, with a slow release under neutral conditions and rapid release of the drug under weakly acidic conditions. According to the in vitro anti-tumor experiments, Ori@ZIF-8 produced higher cytotoxicity than free Ori and induced apoptosis in A549 cancer cells. In conclusion, Ori@ZIF-8 could be a potential pH-responsive carrier to accurately release more oridonins at the tumor site.

Nanoenabled intracellular zinc bursting for efficacious reversal of gefitinib resistance in lung cancer.

Following the identification of specific epidermal growth factor receptor (EGFR)-activating mutations, gefitinib, one of the first-generation tyrosine kinase inhibitors (TKIs), has proven efficacious in targeting NSCLC that is driven by specific EGFR-activating mutations. However, most patients who initially respond to gefitinib, develop acquired resistance. In the current study, we devised a novel strategy to enhance the efficacy of gefitinib. We developed a simple and effective, nano-interrupter termed zeolitic imidazolate framework-8@Gefitinib@hyaluraonic nanoparticle (ZIF-8@G@HA NP). This nanoparticle was prepared by loading gefitinib onto a ZIF-8 nanoplatform followed by coating with hyaluronic acid (HA). The burst of Zn2+ release triggered by pH-sensitive degradation of ZIF-8@G@HA NPs was shown to enhance the efficacy of gefitinib in parental lung carcinoma HCC827 cells and overcame acquired gefitinib resistance in gefitinib drug resistant (GDR) HCC827 cells. We found that when treated with ZIF-8@G@HA NPs, Zn2+ acts synergistically with gefitinib via increased apoptosis in both parental and GDR HCC827 cells. Consistently, this in vitro activity was correlated with in vivo tumor growth inhibition. Interestingly, GDR cells were more sensitive to Zn2+ when compared with parental cells. We further found that ZIF-8 NPs overcame gefitinib resistance by triggering reactive oxygen species (ROS) generation and consequent cell cycle arrest at the G2/M phase, resulting in cancer cell apoptosis. Zn2+ was also found to block P-gp activity, facilitating the accumulation of gefitinib in GDR cells, thus enhancing the anti-tumor efficacy of gefitinib resulting in reversal of gefitinib resistance. Thus, this study offers a novel and promising strategy to surmount acquired gefitinib resistance via cell cycle arrest at the G2/M phase by facilitating gefitinib accumulation in GDR cells.

The magnetic layered double hydroxide/zeolitic imidazolate framework-8 nanocomposite coupled with HPLC-MS/MS for the detection of heterocyclic aromatic amines in thermally processed meat.

In this research, a novel magnetic nanocomposite (Fe3O4@Zn/Al-LABSA-LDH/ZIF-8) was synthesized using Fe3O4 as the magnetic core, layered double hydroxide (LDH) with linear alkylbenzene sulfonic acid (LABSA) intercalation and zeolitic imidazolate framework-8 (ZIF-8) as the shell. Benefiting from the intercalation of LABSA into LDH combined with ZIF-8, the multiple interactions, including π-π stacking, hydrogen bonding, and electrostatic interactions, conferred high selectivity and good extraction capability to the material towards heterocyclic aromatic amines (HAAs). Fe3O4@Zn/Al-LABSA-LDH@ZIF-8 was used as an adsorbent for magnetic solid-phase extraction (MSPE) to enrich HAAs in thermally processed meat samples, followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) detection. The method exhibited a low detection limit (0.021-0.221 ng/g), good linearity (R2 ≥ 0.9999), high precision (RSD < 7.2 %), and satisfactory sample recovery (89.7 % -107.5 %). This research provides a promising approach for developing novel adsorbents in sample preparation and improving analytical performance.

Co-delivery of carboplatin and doxorubicin using ZIF-8 coated chitosan-poly(N-isopropyl acrylamide) nanoparticles through a dual pH/thermo responsive strategy to breast cancer cells.

A dual pH/temperature sensitive core-shell nanoformulation has been developed based on ZIF-8 coated with chitosan-poly(N-isopropyl acrylamide) (CS-PNIPAAm) for co-delivery of doxorubicin (DOX) and carboplatin (CBP) in breast cancer cells. The resulting nanoparticles (NPs) had particle sizes around 200 nm and a zeta potential of about +30 mV. The CBP and DOX loading contents in the final NPs were 11.6 % and 55.54 %, respectively. NPs showed a pH and thermoresponsive drug release profile with a sustained prolonged release under physiological conditions. The in vitro cytotoxicity experiments showed a significant synergism of CBP and DOX to induce the IC50 of 1.96 µg/mL in MCF-7 cells and 4.54 µg/mL in MDA-MB-231 cells. Also, the final NPs were safer than free DOX and CBP on normal cells. The in vitro study confirmed the higher potency of the designed NPs in combination therapy against breast cancer cells with lower side effects than free drugs.

Mechanism of efficient adsorption for arsenic in aqueous solution by zeolitic imidazolate framework­8.

Arsenic (As) is one extremely hazardous and carcinogenic metalloid element. Due to mining, metal smelting, and other human activities, the pollution of water (especially groundwater) and soil caused by As is increasingly serious, which badly threatens the environment and human health. In this study, a zeolite imidazolate framework (ZIF-8) was synthesized at room temperature and employed as an adsorbent to facilitate the adsorption of As(III) and As(V) from the solution. The successful synthesis of ZIF-8 was demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) revealed that its particle size was approximately 80 nm. The adsorption kinetics, adsorption isotherm, solution pH, dose, coexisting ions, and the synonymous elements antimony (Sb) were conducted to study the adsorption of As by ZIF-8 nanoparticles. The maximum saturation adsorption capacity was determined to be 101.47 mg/g and 81.40 mg/g for As(III), and As(V) at initial pH = 7.0, respectively. Apparently, ZIF-8 had a good removal effect on As, and it still maintained a good performance after four cycles. The coexisting ions PO43- and CO32- inhibited the adsorption of both As(III) and As(V). ZIF-8 performed well in removing both As and Sb simultaneously, although the presence of Sb hindered the adsorption of both As(III) and As(V). Both FTIR and XPS indicated the adsorption mechanism of As on ZIF-8: ZIF-8 generates a large amount of Zn-OH on the surface through hydrolysis and partial fracture of Zn-N, both of which form surface complexes with As.

Mechanistic investigation of Pb2+ adsorption on biochar modified with sodium alginate composite zeolitic imidazolate framework-8.

For the serious situation of heavy metal pollution, the use of cheap, clean, and efficient biochar to immobilize heavy metals is a good treatment method. In this paper, SA@ZIF-8/BC was prepared for the adsorption of Pb2+ in solution using sodium alginate (SA) and zeolitic imidazolate framework-8 (ZIF-8) modified corn cob biochar. The results showed that the specific surface area of modified biochar was greatly improved, with good adsorption capacity for Pb2+, strong anti-interference ability, and good economy. At the optimal adsorption pH of 5, the adsorption model of Pb2+ by SA@ZIF-8/BC was more consistent with the pseudo-second-order kinetic model and Langmuir isotherm model. This indicates that the adsorption of Pb2+ by SA@ZIF-8/BC is chemisorption and monolayer adsorption. The maximum adsorption of modified biochar was 300 mg g-1, which was 2.38 times higher than that of before modified BC (126 mg g-1). The shift in binding energy of functional groups before and after adsorption of SA@ZIF-8/BC was studied by XPS, and it was found that hydroxyl and carboxyl groups played an important role in the adsorption of Pb2+. It was demonstrated that this novel adsorbent can be effectively used for the treatment of Pb pollution in wastewater.

Polydopamine-Mediated Metal-Organic Frameworks Modification for Improved Biocompatibility.

Engineered nanomaterials are promising in biomedical application. However, insufficient understanding of their biocompatibility at the cellular and organic levels prevents their widely biomedical applications. Metal-organic frameworks (MOFs) have attracted increasing attention in recent years. In this work, zeolitic imidazolate framework-8 (ZIF-8) and polydopamine (PDA)-modified ZIF-8 are chosen as model nanomaterials due to its emergent role in nanomedicine. In vitro, the results demonstrate that the PDA coating greatly alleviates the cytotoxicity of ZIF-8 to RAW264.7, LO2, and HST6, which represent three different cell types in liver organs. Mechanistically, ZIF-8 entering into the cells can greatly induce the reactive oxygen species generation, which subsequently induces cell cycle delay and autophagy, ultimately leads to enhanced cytotoxicity. Further, human umbilical vein endothelial cells model and zebrafish embryos assay also confirm that PDA can compromise the ZIF-8 toxicity significantly. This study reveals that PDA-coated MOFs nanomaterials show great potential in nano-based drug delivery systems .