Microfluidic intestinal organoid-on-a-chip uncovers therapeutic targets by recapitulating oxygen dynamics of intestinal IR injury.

Increasing evidence demonstrates that mammals have different reactions to hypoxia with varied oxygen dynamic patterns. It takes ∼24 h for tri-gas incubator to achieve steady cell hypoxia, which fails to recapitulate ultrafast oxygen dynamics of intestinal ischemia/reperfusion (IR) injury. Inspired from the structure of native intestinal villi, we engineered an intestinal organoid chip embedded with engineered artificial microvessels based on co-axial microfluidic technology by using pH-responsive ZIF-8/sodium alginate scaffold. The chip was featured on: (i) eight times the oxygen exchange efficiency compared with the conventional device, tri-gas incubator, (ii) implantation of intestinal organoid reproducing all types of intestinal epithelial cells, and (iii) bio-responsiveness to hypoxia and reoxygenation (HR) by presenting metabolism disorder, inflammatory reaction, and cell apoptosis. Strikingly, it was found for the first time that Olfactomedin 4 (Olfm4) was the most significantly down-regulated gene under a rapid HR condition by sequencing the RNA from the organoids. Mechanistically, OLFM4 played protective functions on HR-induced cell inflammation and tissue damage by inhibiting the NF-kappa B signaling activation, thus it could be used as a therapeutic target. Altogether, this study overcomes the issue of mismatched oxygen dynamics between in vitro and in vivo, and sets an example of next-generation multisystem-interactive organoid chip for finding precise therapeutic targets of IR injury.

Membrane-Based Olefin/Paraffin Separations.

Efficient olefin/paraffin separation is a grand challenge because of their similar molecular sizes and physical properties, and is also a priority in the modern chemical industry. Membrane separation technology has been demonstrated as a promising technology owing to its low energy consumption, mild operation conditions, tunability of membrane materials, as well as the integration of physical and chemical mechanisms. In this work, inspired by the physical mechanism of mass transport in channel proteins and the chemical mechanism of mass transport in carrier proteins, recent progress in channel-based and carrier-based membranes toward olefin/paraffin separations is summarized. Further, channel-based membranes are categorized into membranes with network structures and with framework structures according to the morphology of channels. The separation mechanisms, separation performance, and membrane stability in channel-based and carrier-based membranes are elaborated. Future perspectives toward membrane-based olefin/paraffin separation are proposed.

Enhanced Uptake of Iodide from Solutions by Hollow Cu-Based Adsorbents.

Cu2O exhibits excellent adsorption performance for the removal of I- anions from solutions by doping of metallic Ag or Cu. However, the adsorption process only appears on the surface of adsorbents. To further improve the utilization efficiencies of Cu content of adsorbents in the uptake process of I- anions, hollow spheres of metallic Cu, Cu/Cu2O composite and pure Cu2O were prepared by a facile solvothermal method. Samples were characterized and employed for the uptake of I- anions under various experimental conditions. The results show that Cu content can be tuned by adjusting reaction time. After the core was hollowed out, the uptake capacity of the samples increased sharply, and was proportional to the Cu content. Moreover, the optimal uptake was reached within only few hours. Furthermore, the uptake mechanism is proposed by characterization and analysis of the composites after uptake. Cu-based adsorbents have higher uptake performance when solutions are exposed to air, which further verified the proposed uptake mechanism. Finally, hollow Cu-based adsorbents exhibit excellent selectivity for I- anions in the presence of large concentrations of competitive anions, such as Cl-, SO42- and NO3-, and function well in an acidic or neutral environment. Therefore, this study is expected to promote the development of Cu-based adsorbents into a highly efficient adsorbent for the removal of iodide from solutions.

Strict molecular sieving over electrodeposited 2D-interspacing-narrowed graphene oxide membranes.

To separate small molecules/species, it's crucial but still challenging to narrow the 2D-interspacing of graphene oxide (GO) membranes without damaging the membrane. Here the fast deposition of ultrathin, defect-free and robust GO layers is realized on porous stainless steel hollow fibers (PSSHFs) by a facile and practical electrophoresis deposition (ED) method. In this approach, oxygen-containing groups of GO are selectively reduced, leading to a controlled decrease of the 2D channels of stacked GO layers. The resultant ED-GO@PSSHF composite membranes featured a sharp cutoff between C2 (ethane and ethene) and C3 (propane and propene) hydrocarbons and exhibited nearly complete rejections for the smallest alcohol and ion in aqueous solutions. This demonstrates the versatility of GO based membranes for the precise separation of various types of mixtures. At the same time, a robust mechanical strength of the ED-GO@PSSHF membrane is also achieved due to the enhanced interaction at GO/support and GO/GO interfaces.Producing graphene oxide membranes with narrow channels is desirable for small molecule separations, but methods to narrow the 2D spacing typically result in membrane damage. Here the authors exploit electrophoresis-deposition to prepare GO membranes that are reduced in situ, leading to narrow and uniform 2D channels.

Amino-Functionalized ZIF-7 Nanocrystals: Improved Intrinsic Separation Ability and Interfacial Compatibility in Mixed-Matrix Membranes for CO2 /CH4 Separation.

Highly permeable and selective, as well as plasticization-resistant membranes are desired as promising alternatives for cost- and energy-effective CO2 separation. Here, robust mixed-matrix membranes based on an amino-functionalized zeolitic imidazolate framework ZIF-7 (ZIF-7-NH2 ) and crosslinked poly(ethylene oxide) rubbery polymer are successfully fabricated with filler loadings up to 36 wt%. The ZIF-7-NH2 materials synthesized from in situ substitution of 2-aminobenzimidazole into the ZIF-7 structure exhibit enlarged aperture size compared with monoligand ZIF-7. The intrinsic separation ability for CO2 /CH4 on ZIF-7-NH2 is remarkably enhanced as a result of improved CO2 uptake capacity and diffusion selectivity. The incorporation of ZIF-7-NH2 fillers simultaneously makes the neat polymer more permeable and more selective, surpassing the state-of-the-art 2008 Robeson upper bound. The chelating effect between metal (zinc) nodes of fillers and ester groups of a polymer provides good bonding, enhancing the mechanical strength and plasticization resistance of the neat polymer membrane. The developed novel ZIF-7 structure with amino-function and the resulting nanocomposite membranes are very attractive for applications like natural-gas sweetening or biogas purification.

Enhanced C3H6/C3H8 separation performance on MOF membranes through blocking defects and hindering framework flexibility by silicone rubber coating.

The polydimethylsiloxane (PDMS) coating penetrated into the underneath ZIF-8 polycrystalline membrane not only blocking the inter-crystalline defects but also hindering the flexibility of the ZIF-8 framework, resulting in an unusual and highly desired increase in the separation selectivity of the C3H6/C3H8 mixture under high feeding pressures.

From Discrete Molecular Cages to a Network of Cages Exhibiting Enhanced CO2 Adsorption Capacity.

We have adopted the concept of "cage to frameworks" to successfully produce a Na-N connected coordination networked cage Na-NC1 by using a [3+6] porous imine-linked organic cage NC1 (Nanjing Cage 1) as the precursor. It is found that Na-NC1 exhibits hierarchical porosity (inherent permanent voids and interconnected channel) and gas sorption measurements reveal a significantly enhanced CO2 uptake (1093 cm3 g-1 at 23 bar and 273 K) than that of NC1 (162 cm3 g-1 under the same conditions). In addition, Na-NC1 exhibits very low CO2 adsorption enthalpy making it a good candidate for porous materials with both high CO2 storage and low adsorption enthalpy.

Unravelling surface and interfacial structures of a metal-organic framework by transmission electron microscopy.

Metal-organic frameworks (MOFs) are crystalline porous materials with designable topology, porosity and functionality, having promising applications in gas storage and separation, ion conduction and catalysis. It is challenging to observe MOFs with transmission electron microscopy (TEM) due to the extreme instability of MOFs upon electron beam irradiation. Here, we use a direct-detection electron-counting camera to acquire TEM images of the MOF ZIF-8 with an ultralow dose of 4.1 electrons per square ångström to retain the structural integrity. The obtained image involves structural information transferred up to 2.1 Å, allowing the resolution of individual atomic columns of Zn and organic linkers in the framework. Furthermore, TEM reveals important local structural features of ZIF-8 crystals that cannot be identified by diffraction techniques, including armchair-type surface terminations and coherent interfaces between assembled crystals. These observations allow us to understand how ZIF-8 crystals self-assemble and the subsequent influence of interfacial cavities on mass transport of guest molecules.

Fabrication of magnetically responsive HKUST-1/Fe3O4 composites by dry gel conversion for deep desulfurization and denitrogenation.

Selective adsorption by use of metal-organic frameworks (MOFs) is an effective method for purification of hydrocarbon fuels. In consideration that the adsorption processes proceed in liquid phases, separation and recycling of adsorbents should be greatly facilitated if MOFs were endowed with magnetism. In the present study, we reported for the first time a dry gel conversion (DGC) strategy to fabricate magnetically responsive MOFs as adsorbents for deep desulfurization and denitrogenation. The solvent is separated from the solid materials in the DGC strategy, and vapor is generated at elevated temperatures to induce the growth of MOFs around magnetic Fe3O4 nanoparticles. This strategy can greatly simplify the complicated procedures of the well-known layer-by-layer method and avoid the blockage of pores confronted by introducing magnetic Fe3O4 nanoparticles to the pores of MOFs. Our results show that the adsorbents are capable of efficiently removing aromatic sulfur and nitrogen compounds from model fuels, for example removing 0.62mmolg-1S and 0.89mmolg-1N of thiophene and indole, respectively. In addition, the adsorbents are facile to separate from liquid phases by use of an external field. After 6 cycles, the adsorbents still show a good adsorption capacity that is comparable to the fresh one.

Zinc-substituted ZIF-67 nanocrystals and polycrystalline membranes for propylene/propane separation.

Continuous ZIF-67 polycrystalline membranes with effective propylene/propane separation performances were successfully fabricated through the incorporation of zinc ions into the ZIF-67 framework. The separation factor increases from 1.4 for the pure ZIF-67 membrane to 50.5 for the 90% zinc-substituted ZIF-67 membrane.

Molecular dynamics simulations on gate opening in ZIF-8: identification of factors for ethane and propane separation.

Gate opening of zeolitic imidazolate frameworks (ZIFs) is an important microscopic phenomenon in explaining the adsorption, diffusion, and separation processes for large guest molecules. We present a force field, with input from density functional theory (DFT) calculations, for the molecular dynamics simulation on the gate opening in ZIF-8. The computed self-diffusivities for sorbed C1 to C3 hydrocarbons were in good agreement with the experimental values. The observed sharp diffusion separation from C2H6 to C3H8 was elucidated by investigating the conformations of the guest molecules integrated with the flexibility of the host framework.

Sharp separation of C2/C3 hydrocarbon mixtures by zeolitic imidazolate framework-8 (ZIF-8) membranes synthesized in aqueous solutions.

Exceptional high quality ZIF-8 membranes prepared through a novel seeded growth method in aqueous solutions at near room temperature exhibit excellent separation performance for C2/C3 hydrocarbon mixtures. The separation factors for mixtures of ethane/propane, ethylene/propylene and ethylene/propane are ∼80, ∼10 and ∼167, respectively.

Rapid synthesis of zeolitic imidazolate framework-8 (ZIF-8) nanocrystals in an aqueous system.

We report here the first example of ZIF materials synthesized in aqueous solution. The synthesis was performed at room temperature and typically took several minutes compared to hours and days in non-aqueous conditions. The obtained product were ZIF-8 nanocrystals having size of ~85 nm and showed excellent thermal, hydrothermal and solvothermal stabilities.

Versatile preparation of monodisperse poly(furfuryl alcohol) and carbon hollow spheres in a simple microfluidic device.

Monodisperse PFA and carbon hollow microspheres have been prepared without templates in a single synthesis process by a microfluidic methodology.

Preparation of uniform nano-sized zeolite A crystals in microstructured reactors using manipulated organic template-free synthesis solutions.

Zeolite A nanocrystals (100-240 nm) with well-developed crystal faces and uniform particle size distribution have been prepared at 80 degrees C for ca. 7.5 min in a two-phase liquid segmented microfluidic reactor using a manipulated organic template-free synthesis solution.