ZIF-8 degrades in cell media,serum, and some—but not all—common laboratory buffers

ABSTRACT

Drug delivery using metal-organic frameworks (MOF) has elicited interest in their biocompatibility; however, few studies have been conducted on their stability in common buffers, cell media, and blood proteins. In particular, the use of ZIF-8, a MOF interconnected by Zn and methylimidazole, has been frequently employed. In this study, we tested single crystals of ZIF-8 with common laboratory buffers, cell media, and serum, and noted several issues. Buffers containing phosphate and bicarbonate alter the appearance and composition of ZIF-8; however, these buffers do not appear to cause cargo to leak out even when the ZIF-8 itself is displaced by phosphates. On the other hand, serum dissolves ZIF-8, causing premature cargo release. Our results show that ZIF-8 undergoes surface chemistry changes that may affect the interpretation of cellular uptake and cargo release data. On the other hand, it provides a rational explanation as to how ZIF-8 neatly dissolves in vivo.     

Template-controlled reactivity: Following nature's way to design and construct metal-organic polyhedra and polygons

We show how a template-controlled reaction performed in the organic solid state can be used to construct a molecule that functions as an organic building unit of both a metal-organic polyhedron and polygon. The template is a small organic molecule that organizes two olefins via hydrogen bonds for a [2+2] photodimerization. The process of utilizing a molecule to build a molecule that is subsequently used for self-assembly is inspired by the general two-step process of template-directed synthesis and self-assembly of Nature that is used to construct large, functional self-assembled structures.     

Ag(TCNQ)准一维微米结构的制备及表征

利用溶液化学反应法制备了准一维结构的金属有机配合物Ag(TCNQ). X射线衍射(XRD)表明，所制备的Ag(TCNQ)为晶态结构;扫描电子显微镜(SEM)的观察证明，Ag(TCNQ)为准一维的微米管或线；Raman 测试结果表明，单根的Ag(TCNQ)形成时,Ag原子与TCNQ分子之间发生了电荷转移.对样品的制备工艺,即 Ag膜厚度和浸入溶液的反应时间对生成Ag(TCNQ)晶体形貌的影响进行了研究.结果表明，Ag膜越薄，生长出的晶体越稀疏;Ag膜与TCNQ乙腈溶液的反应时间影响其形貌的变化.反应历经三个阶段,晶体形成和长大阶段、反应完全阶段及溶解阶段.     

A μ3-OH- bridged two-dimensional zinc(Ⅱ) coordination polymer based on an anthryl ligand：Synthesis, characterization and luminescent properties

A two-dimensional (2D) 3,3,3,4,5,5,6-connected ZnⅡ coordination compound [Zn5(L)2(OH)6]∞ (L=9,10-dioxo-9,10-dihydroanthracene-1,8-dicarboxylate) has been synthesized and characterized by IR, elemental analysis, X-ray powder diffraction and single crystal X-ray diffraction analysis. Moreover, the luminescent properties of the ligand and corresponding compound have been briefly investigated.     

Nonlinear optical metal-organic frameworks for ratiometric temperature sensing in physiological range

The precise and real-time sensing of the temperature within the physiological range is of great significance in biology and medicine. Here, a Zn-based metal-organic framework (MOF) named Zn-TCOMA is synthesized with good SHG performance due to its unique structure of the ligand and 3D frameworks. By encapsulating the two-photon fluorescent dye DMASE into the pores of Zn-TCOMA, the composite Zn-TCOMA?DMASE is obtained and simultaneously exhibits SHG response and two-photon fluorescence. Utilizing the intensity ratio between two-photon fluorescence of DMASE and SHG signal of Zn-TCOMA, Zn-TCOMA?DMASE exhibits ratiometric temperature sensing property at physiological temperature region of 20～60 °C with high sensitivity. This MOF thermometer also shows excellent repeatability, good biocompatibility, and high temperature resolution of 0.018 °C, opening a new avenue to develop diverse optical thermometric or thermographic applications in biotechnology or other areas.     

Highly N/O co-doped ultramicroporous carbons derived from nonporous metal-organic framework for high performance supercapacitors

A new nonporous Zn-based metal-organic framework (NPMOF) synthesized from a high nitrogen-containing rigid ligand was converted into porous carbon materials by direct carbonization without adding additional carbon sources. A series of NPMOF-derived porous carbons with very high N/O contents (24.1% for NPMOF-700, 20.2% for NPMOF-800, 15.1% for NPMOF-900) were prepared by adjusting the pyrolysis temperatures. The NPMOF-800 fabricated electrode exhibits a high capacitance of 220 F/g and extremely large surface area normalized capacitance of 57.7 μF/cm² compared to other reported MOF-derived porous carbon electrodes, which could be attributed to the abundant ultramicroporosity and high N/O co-doping. More importantly, symmetric supercapacitor assembled with the MOF-derived carbon manifests prominent stability, i.e., 99.1% capacitance retention after 10,000 cycles at 1.0 A/g. This simple preparation of MOF-derived porous carbon materials not only finds an application direction for a variety of porous or even nonporous MOFs, but also opens a way for the production of porous carbon materials for superior energy storage.     

Room temperature solution-phase synthesis of flower-like nanostructures of [Ni3(BTC)2·12H2O] and their conversion to porous NiO

Hierarchical flower-like architectures of[Ni₃（BTC）₂·12H₂O]（BTC³=benzene-1,3,5-tricarboxylate） were successfully prepared by a simple solution-phase method under mild conditions without any template or surfactant.Phase-pure porous NiO nanocrystals were obtained by annealing the Ni-BTC complex without significant alteration in morphology.The product was characterized by X-ray diffraction techniques,field-emission scanning electron microscopy（FESEM）.transmission electron microscopy（TEM） and high-resolution TEM（HRTEM）.The catalytic effect of the NiO product was investigated on the thermal decomposition of ammonium perchlorate（AP） and it was found that the annealed NiO product has higher catalytic activity than the commercial NiO.     

磺酸功能化金属-有机骨架吸附脱氮性能

以硝基甲烷为溶剂,采用三氟甲磺酸酐(Tf2O)和浓硫酸对金属有机骨架材料MIL-101(Cr){Cr3F(H2O)2O[(O2C)-C6H4-(CO2)]3nH2O(n~25)}进行磺酸功能化修饰,使其孔壁配体上形成磺酸基团.通过改变MIL-101(Cr)、Tf2O和浓硫酸的摩尔配比,得到含有不同磺酸基团数量的S-MIL-101(Cr),对磺化后的材料进行了X射线衍射(XRD)、傅里叶变换红外(FTIR)、氮气物理吸附、酸碱电位滴定以及热重分析(TGA)表征.结果表明,磺酸功能化后MIL-101(Cr)的孔道结构仍然保持,比表面积和孔径有所下降,表面磺酸基团的数量根据磺化程度的不同从0.21到0.42 mmol g-1不等.将磺酸功能化后的MIL-101(Cr)用于液体燃料的吸附脱氮,发现磺酸功能化能够增强MIL-101(Cr)与含氮化合物的相互作用,有利于其对碱性氮化物的吸附脱除.相对于未经磺化的样品,按照摩尔配比n(MIL-101(Cr)):n(H2SO4):n(Tf2O)=1:3:4.5反应得到的磺酸功能化MIL-101(Cr)对喹啉和吲哚的吸附量提高较大,其对喹啉和吲哚的Langmuir最大吸附量分别提高了12.2%和6.3%.通过乙醇洗涤,吸附剂可再生,经过三次再生之后的吸附剂对模拟燃料中含氮化合物的吸附量没有明显的降低.     

Control of pore environment in highly porous carbon materials for C2H6/C2H4 separation with exceptional ethane uptake

Adsorptive separation of C₂H₆ from C₂H₄ by adsorbents is an energy-efficient and promising method to boost the polymer grades C₂H₄ production. However, that C₂H₆ and C₂H₄ display very similar physical properties, making their separation extremely challenging. In this work, by regulating the pore environment in a family of chitosan-based carbon materials (C-CTS-1, C-CTS-2, C-CTS-4, and C-CTS-6)- we target ultrahigh C₂H₆ uptake and C₂H₆/C₂H₄ separation, which exceeds most benchmark carbon materials. Explicitly, the C₂H₆ uptake of C-CTS-2 (166 cm³/g at 100 kPa and 298 K) has the second-highest adsorption capacity among all the porous materials. In addition, C-CTS-2 gives C₂H₆/C₂H₄ selectivity of 1.75 toward a 1:15 mixture of C₂H₆/C₂H₄. Notably, the adsorption enthalpies for C₂H₆ in C-CTS-2 are low (21.3 kJ/mol), which will facilitate regeneration in mild conditions. Furthermore, C₂H₆/C₂H₄ separation performance was confirmed by binary breakthrough experiments. Under different ethane/ethylene ratios, C-CTS-X extracts a low ethane concentration from an ethane/ethylene mixture and produces high-purity C₂H₄ in one step. Spectroscopic measurement and diffraction analysis provide critical insight into the adsorption/separation mechanism. The nitrogen functional groups on the surface play a vital role in improving C₂H₆/C₂H₄ selectivity, and the adsorption capacities depend on the pore size and micropore volume. Moreover, these robust porous materials exhibit outstanding stability (up to 800 °C) and can be easily prepared on a large scale (kg) at a low cost (～$26 per kg), which is very significant for potential industrial applications.     

Target-induced mimic enzyme deactivation based on mixed-node metal-organic frameworks for colorimetric assay of hydrogen sulfide

Accurate detection of hydrogen sulfide (H₂S) is of great significance for environmental monitoring and protection. We propose a colorimetric method for the detection of H₂S by the use of mixed-node Cu-Fe metal organic frameworks (Cu-Fe MOFs) as highly efficient mimic enzymes for target-induced deactivation. The Cu-Fe MOFs were synthesized by a simple solvothermal method and could catalyze the H₂O₂ mediated oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to oxTMB with a blue color. The presence of dissolved H₂S would deactivate the mimic enzymes, and then the blue color disappeared. The mechanism of the sensor was discussed by steady-state kinetic analysis. The designed assay was highly sensitive for H₂S detection with a linear range of 0−80 μmol/L and a detection limit of 1.6 μmol/L. Moreover, some potential substances in the water samples had no interference. This method with the advantages of low cost, high sensitivity, selectivity, and visual readout with the naked eye was successfully applied to the determination of H₂S in industrial wastewater samples.