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1. Rapid mechanochemical encapsulation of biocatalysts into robust metal–organic frameworks

   https://doi.org/10.1038/s41467-019-12966-0  

   Wei, Tz-Han ; Wu, Shi-Hong ; Huang, Yi-Da ; Lo, Wei-Shang ; Williams, Benjamin P. ; Chen, Sheng-Yu ; Yang, Hsun-Chih ; Hsu, Yu-Shen ; Lin, Zih-Yin ; Chen, Xin-Hua ; et al ( November 2019 , Nature Communications)

   Metal–organic frameworks (MOFs) have recently garnered consideration as an attractive solid substrate because the highly tunable MOF framework can not only serve as an inert host but also enhance the selectivity, stability, and/or activity of the enzymes. Herein, we demonstrate the advantages of using a mechanochemical strategy to encapsulate enzymes into robust MOFs. A range of enzymes, namely β-glucosidase, invertase, β-galactosidase, and catalase, are encapsulated in ZIF-8, UiO-66-NH₂, or Zn-MOF-74 via a ball milling process. The solid-state mechanochemical strategy is rapid and minimizes the use of organic solvents and strong acids during synthesis, allowing the encapsulation of enzymes intomore »three prototypical robust MOFs while maintaining enzymatic biological activity. The activity of encapsulated enzyme is demonstrated and shows increased resistance to proteases, even under acidic conditions. This work represents a step toward the creation of a suite of biomolecule-in-MOF composites for application in a variety of industrial processes.

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2. Self-decontaminating nanofibrous filters for efficient particulate matter removal and airborne bacteria inactivation

   https://doi.org/10.1039/D0EN01230K  

   Zhu, Zan ; Zhang, Yu ; Bao, Liang ; Chen, Jianping ; Duan, Shun ; Chen, Sheng-Chieh ; Xu, Ping ; Wang, Wei-Ning ( April 2021 , Environmental Science: Nano)

   With the increased bacteria-induced hospital-acquired infections (HAIs) caused by bio-contaminated surfaces, the requirement for a safer and more efficient antibacterial strategy in designing personal protective equipment (PPE) such as N95 respirators is rising with urgency. Herein, a self-decontaminating nanofibrous filter with a high particulate matter (PM) filtration efficiency was designed and fabricated via a facile electrospinning method. The fillers implemented in the electrospun nanofibers were constructed by grafting a layer of antibacterial polymeric quaternary ammonium compound (QAC), that is, poly[2-(dimethyl decyl ammonium) ethyl methacrylate] (PQDMAEMA), onto the surface of metal–organic framework (MOF, UiO-66-NH 2 as a model) to form themore »active composite UiO-PQDMAEMA. The UiO-PQDMAEMA filter demonstrates an excellent PM filtration efficiency (>95%) at the most penetrating particle size (MPPS) of 80 nm, which is comparable to that of the commercial N95 respirators. Besides, the UiO-PQDMAEMA filter is capable of efficiently killing both Gram-positive ( S. epidermidis ) and Gram-negative ( E. coli ) airborne bacteria. The strong electrostatic interactions between the anionic cell wall of the bacteria and positively charged nitrogen of UiO-PQDMAEMA are the main reasons for severe cell membrane disruption, which leads to the death of bacteria. The present work provides a new avenue for combating air contamination by using the QAC-modified MOF-based active filters.« less
3. Highly H ₂ O permeable ionic liquid encapsulated metal–organic framework membranes for energy-efficient air-dehumidification

   https://doi.org/10.1039/d0ta07780a  

   Park, Sunghwan ; Jeong, Hae-Kwon ( January 2020 , Journal of Materials Chemistry A)

   Isothermal membrane-based air dehumidification (IMAD) is much more energy-efficient and economical than traditional air-dehumidification technologies. There are, however, no practical IMAD process technologies currently available mainly due to limitations of current membranes. Ionic liquids (ILs) are a promising air-dehumidification membrane material. Current supported IL membranes suffer from poor stability, limiting their performances. Herein, we propose new stable IL membranes, encapsulated IL membranes (EILMs) by encapsulating 1-butyl-3-methylimidazolium bromide ([C 4 MIM][Br]) into ultrathin polycrystalline UiO-66-NH 2 metal–organic framework membranes via a ship-in-a-bottle method. The stability of IL membranes is significantly enhanced due to the IL entrapped in the pore cages ofmore »UiO-66-NH 2 . The EILMs show unprecedentedly high H 2 O permeance (∼2.36 × 10 −4 mol m −2 s −1 Pa −1 ), an order of magnitude greater than that of the most permeable air-dehumidification membranes reported so far. Furthermore, the encapsulated [C 4 MIM][Br] drastically increases the H 2 O/N 2 separation factor to ∼1560, satisfying the minimally required H 2 O/N 2 separation performance for commercially viable air-dehumidification.« less
4. Ionic Liquid Welding of the UIO-66-NH2 MOF to Cotton Textiles

   Bunge, M ; Pasciak, E ; Choi, J ; Haverhals, L ; Reichert, W ; Glover, T. ( October 2020 , Industrial engineering chemistry research)

   Ionic liquid based fiber welding has been used to attach the metal−organic framework (MOF) UiO-66-NH2to cotton fibers. The results show that by controlling the extent of the welding process, it is possible to produce fibers that contain a high surface area (approximately 50−100 m2/ g), an X-ray diffraction pattern consistent with UiO-66-NH2, and fibers that are chemically reactive to dimethyl 4-nitrophenyl phosphate (DMNP), a common chemical weapon simulant. The ionic liquid/MOF welding solution can be applied by directly placing the fabric in the welding solution or by utilizing an airbrushing technique. Both welding techniques are shown to be scalable withmore »results collected on approximately 1×1, 5 ×5, and 15.5×15.5 in. swatches. The results are also applicable to weaving methods where the MOF is welded to individual threads and subsequently woven into a textile. The results provide an industrially scalable method of attaching a wide variety of MOFs to cotton textiles, which does not require synthesizing the MOF in the presence of the textile.« less
5. Membrane-supported metal organic framework based nanopacked bed for protection against toxic vapors and gases

   https://doi.org/https://doi.org/10.1016/j.seppur.2020.117406  

   Song, Yufeng ; Chau, John ; Sirkar, Kamalesh K. ; Peterson, Gregory W. ; Beuscher, Uwe ( July 2020 , Separation and purification technology)

   Defense against small molecule toxic gases is an important aspect of protection against chemical and biological threat as well as chemical releases from industrial accidents. Current protective respirators/garments cannot effectively block small molecule toxic gases and vapors and retain moisture transmission capability without a heavy burden. Here, we developed a nanopacked bed of nanoparticles of UiO-66-NH₂ metal organic framework (MOF) by synthesizing them in the pores of microporous expanded polytetrafluoroethylene (ePTFE) membranes. The submicron scale size of membrane pores ensures a large surface area of MOF nanoparticles which can capture/adsorb and react with toxic gas molecules efficiently. It was demonstratedmore »that the microporous ePTFE membrane with UiO-66-NH₂ MOF grown inside and around the membrane can defend against ammonia for a significant length of time while allowing passage of moisture and nitrogen. It was also demonstrated that the MOF-loaded ePTFE membrane could provide significant protection from Cl₂ intrusion as well as intrusion from 2-chloroethyl ethyl sulfide (CEES) (a simulant for sulfur mustard). Such MOF-filled membranes exhausted by NH₃ breakthrough experiments were regenerated conveniently by heating at 60 °C for one week under vacuum for further/repeated use; a single regenerated membrane could block NH₃ for 200–300 min. The moisture permeability of such a membrane/nanopacked bed was considerably above the breathability threshold value of 2000 g/m² -day. The results suggest that microporous membranes filled with reactive MOF nanoparticles could be designed as protective barriers against toxic gases/vapors, e.g., NH₃ and Cl₂ and yet be substantially permeable to H₂O and air.« less