Dynamic Metallosupramolecular Cages Containing 12 Adaptable Pockets for High-Order Guest Binding Beyond Biomimicry.

Molecular recognition lies at the heart of biological functions, which inspires lasting research in artificial host syntheses to mimic biomolecules that can recognize, process, and transport molecules with the highest level of complexity; nonetheless, the design principle and quantifying methodology of artificial hosts for multiple guests (≥4) remain a formidable task. Herein, we report two rhombic dodecahedral cages [(Zn/Fe)8Pd6-MOC-16], which embrace 12 adaptive pockets for multiguest binding with distinct conformational dynamics inherent in metal-center lability and are able to capture 4-24 guests to manifest a surprising complexity of binding scenarios. The exceptional high-order and hierarchical encapsulation phenomena suggest a wide host-guest dynamic-fit, enabling conformational adjustment and adaptation beyond the duality of induced-fit and conformational selection in protein interactions. A critical inspection of the host-guest binding events in solution has been performed by NMR and ESI-MS spectra, highlighting the importance of acquiring a reliable binding repertoire from different techniques and the uncertainty of quantifying the binding affinities of multiplying guests by an oversimplified method.

Light-Driven Molecular Motors Boost the Selective Transport of Alkali Metal Ions through Phospholipid Bilayers.

A hydrophobic light-driven rotary motor is functionalized with two 18-crown-6 macrocycles and incorporated into phospholipid bilayers. In the presence of this molecular construct, fluorescence assays and patch clamp experiments show the formation of selective alkali ion channels through the membrane. Further, they reveal a strongly accelerated ion transport mechanism under light irradiation. This increase of the fractional ion transport activity (up to 400%) is attributed to the out-of-equilibrium actuation dynamics of the light-driven rotary motors, which help to overcome the activation energy necessary to achieve translocation of alkali ions between macrocycles along the artificial channels.

Self-Assembled Artificial Ion-Channels toward Natural Selection of Functions.

Owing to their significant physiological functions, especially as selective relays for translocation of physiological relevant species through cellular membranes, natural ion channels play important role in the living organisms. During the last decades, the field of self-assembled ion channels has been continuously developed. Convergent multidimensional self-assembly strategies have been used for the synthesis of unimolecular channels or non-covalent self-organized channels, designed to mimic natural ion channel proteins and for which a rich array of interconverting or adaptive channel conductance states can be observed. In this review, we give an overview on the development of various self-assembled artificial channels in a bottom-up approach, especially their design, self-assembly behaviour, transport activity in lipid bilayer membranes, mechanism of transport and comparison with natural ion channels. Finally, we discuss their applications, the potential challenges facing in this field as well as future development and perspectives.

A Voltage-Responsive Synthetic Cl- -Channel Regulated by pH.

Transmembrane protein channels are an important inspiration for the design of artificial ion channels. Their dipolar structure helps overcome the high energy barrier to selectively translocate water and ions sharing one pathway, across the cell membrane. Herein, we report that the amino-imidazole (Imu) amphiphiles self-assemble via multiple H-bonding to form stable artificial Cl- -channels within lipid bilayers. The alignment of water/Cl- wires influences the conduction of ions, envisioned to diffuse along the hydrophilic pathways; at acidic pH, Cl- /H+ symport conducts along a partly protonated channel, while at basic pH, higher Cl- /OH- antiport translocate through a neutral channel configuration, which can be greatly activated by applying strong electric field. This voltage/pH regulated channel system represents an unexplored alternative for ion-pumping along artificial ion-channels, parallel to that of biology.

Progressive Folding and Adaptive Multivalent Recognition of Alkyl Amines and Amino Acids in p-Sulfonatocalix[4]arene Hosts: Solid-State and Solution Studies.

Invited for this month's cover is the group of Dr. Mihail Barboiu from the Institut Europeen des Membranes of Montpellier, France and the Lehn Institute of Functional Materials at Sun-yat Sen University in Guangzhou, China. The cover picture shows the molecular recognition of folded 1,ω-amino-acids guests within p-sulfonatocalix[4]arene host anions stabilized with alternating hydrated cations and water molecules. Read the full text of the article at 10.1002/cplu.202000232.

Progressive Folding and Adaptive Multivalent Recognition of Alkyl Amines and Amino Acids in p-Sulfonatocalix[4]arene Hosts: Solid-State and Solution Studies.

Calix[4]arenes have the ability to encapsulate biomimetic guests, offering interesting opportunities to explore their molecular recognition, very close to biological scenarios. In this study, p-sulfonatocalix[4]arene (C4 A) anions and hydrated alkali cations have been used for the in situ recognition of cationic 1,ω-diammonium-alkanes and 1,ω-amino-acids of variable lengths. NMR spectroscopy illustrates that these systems are stable in aqueous solution and the interaction process involves several binding states or stabilized conformations within the C4 A anion, depending of the nature of the guest. DOSY experiments showed that monomeric 1 : 1 host-guest species are present, while the cation does not influence their self-assembly in solution. The folded conformations observed in the solid-state X-ray single-crystal structures shed light on the constitutional adaptivity of flexible chains to environmental factors. Futhermore, a comprehensive screening of 30 single crystal structures helped to understand the in situ conformational fixation and accurate determination of the folded structures of the confined guest molecules, with a compression up to 40 % compared with their linear conformations.

Visible-Light Photocatalysis of Asymmetric [2+2] Cycloaddition in Cage-Confined Nanospace Merging Chirality with Triplet-State Photosensitization.

Although the photodimerization of acenaphthylene (ACE) has been known for 100 years, the asymmetric cycloaddition of its 1-substituted derivatives is unknown. Herein, we report a supramolecular photochirogenic approach in which a homochiral and photoactive Δ/Λ-[Pd6 (RuL3 )8 ]28+ metal-organic cage (Δ/Λ-MOC-16) is used as a supramolecular reactor for the enantioselective exited-state photocatalysis of 1-Br-ACE. Owing to preorganization of the substrates by the supramolecular cage, stereochemical control of the triplet state, and nanospace transfer of energy and chirality, the cycloaddition of ACE proceeded with high selectivity for the formation of anti over syn stereoisomers, whereas the regio-, stereo-, and enantioselective cycloaddition of unsymmetrical 1-Br-ACE showed effective enantiodifferentiation of a pair of anti head-to-head stereoisomers. The enzyme-mimicking photocatalysis was verified by catalytic turnover, rate enhancement, and competing-guest inhibition experiments.

Self-Assembled Columnar Triazole Quartets: An Example of Synergistic Hydrogen-Bonding/Anion-π Interactions.

The self-assembly of triazole amphiphiles was examined in solution, the solid state, and in bilayer membranes. Single-crystal X-ray diffraction experiments show that stacked protonated triazole quartets (T4 ) are stabilized by multiple strong interactions with two anions. Hydrogen bonding/ion pairing of the anions are combined with anion-π recognition to produce columnar architectures. In bilayer membranes, low transport activity is observed when the T4 channels are operated as H+ /X- translocators, but higher transport activity is observed for X- in the presence of the K+ -carrier valinomycin. These self-assembled superstructures, presenting intriguing structural behaviors such as directionality, and strong anion encapsulation by hydrogen bonding supported by vicinal anion-π interactions can serve as artificial supramolecular channels for transporting anions across lipid bilayer membranes.

"Calix[4]-box" cages promote the formation of amide bonds in water in the absence of coupling reagents.

The present work shows that encapsulation can be used to promote amide bond formation in water under mild conditions, in the absence of carbodiimide coupling agents.

Research and application of transnasal transesophageal echocardiography probe.

The intubation of conventional transesophageal echocardiography (TEE) probes into patients causes serious esophagus irritation, and thus the use of TEE probes in pediatric practice is limited. In this study, we aimed at the development of a special probe which could be inserted through the nasopharyngeal cavity into the esophagus to obtain the same high-quality echocardiography images as those obtained by conventional TEE and improve patients' experience. During the examination, the patients felt relaxed for a longer time and cooperated with the sonographers in the process of cardiac catheterization conducted in the surgery room or the intensive care unit (ICU), resulting in improved accuracy of the diagnosis and timely administration of appropriate treatment. Two years ago, Prof. Xin-fang WANG put theories into practice by inserting the probe through the nasal cavity and pharynx into the esophagus of volunteers to successfully detect the heart and great vessels at the retrocardiac space. Later, Prof. Ming-xing XIE performed the transnasal TEE examination in 12 atrial septal defect (ASD) patients and proved the safety and reliability of this method, which could become a new way for clinical diagnosis and treatment.

Dynamic Spacer Installation for Multirole Metal-Organic Frameworks: A New Direction toward Multifunctional MOFs Achieving Ultrahigh Methane Storage Working Capacity.

A robust Zr-MOF (LIFM-28) containing replaceable coordination sites for additional spacer installation has been employed to demonstrate a swing- or multirole strategy for multifunctional MOFs. Through reversible installation/uninstallation of two types of spacers with different lengths and variable functional groups, different tasks can be accomplished using the same parent MOF. An orthogonal optimizing method is applied with seven shorter (L1-7) and six longer (L8-13) spacers to tune the functionalities, achieving multipurpose switches among gas separation, catalysis, click reaction, luminescence, and particularly, ultrahigh methane storage working capacity at 5-80 bar and 298 K.

A Robust Metal-Organic Framework Combining Open Metal Sites and Polar Groups for Methane Purification and CO2 /Fluorocarbon Capture.

A 3D porous perchlorinated metal-organic framework (MOF), LIFM-26, featuring dual functionality, that is, functional polar groups and open metal sites, has been synthesized using perchlorinated linear dicarboxylate to link trigonal prismatic Fe3 (µ3 -O) units. LIFM-26 exhibits good thermal and chemical stability, and possesses high porosity with a BET surface area of 1513 m2 g-1 , compared with isoreticular MOF-235 and Fe3 O(F4 BDC)3 (H2 O)3 (F4 BDC=2,3,5,6-tetrafluorobenzene-1,4-dicarboxylate). Most strikingly, LIFM-26 features good gas sorption/separation performance at 298 K and 1 atm with IAST selectivity values reaching up to 36, 93, 23, 11, 46, and 202 for CO2 /CH4 , CO2 /N2 , C2 H4 /CH4 , C2 H6 /CH4 , C3 H8 /CH4 , and R22/N2 (R22=CHClF2 ), respectively, showing potential for use in biogas/natural gas purification and CO2 /R22 capture.

Rigidifying Effect of Metal-Organic Frameworks: Protect the Conformation, Packing Mode, and Blue Fluorescence of a Soft Piezofluorochromic Compound under Pressures up to 8 MPa.

We demonstrate that the conformation, packing mode, and blue fluorescence of a soft piezofluorochromic compound can be preserved by structurally fixing it into a solid calcium metal-organic framework (Ca-MOF, LIFM-40), which can survive pressures up to 8 MPa. DFT calculations have been combined with experimental results to indicate that the ligands adopting a specific conformation and packing without π···π interactions are the reasons for its rigidified blue emission.

Precise Modulation of the Breathing Behavior and Pore Surface in Zr-MOFs by Reversible Post-Synthetic Variable-Spacer Installation to Fine-Tune the Expansion Magnitude and Sorption Properties.

To combine flexibility and modifiability towards a more controllable complexity of MOFs, a post-synthetic variable-spacer installation (PVSI) strategy is used to implement kinetic installation/ uninstallation of secondary ligands into/from a robust yet flexible proto-Zr-MOF. This PVSI process features precise positioning of spacers with different length, size, number, and functionality, enabling accurate fixation of successive breathing stages and fine-tuning of pore surface. It shows unprecedented synthetic tailorability to create complicated MOFs in a predictable way for property modification, for example, CO2 and R22 adsorption/separation, thermal/chemical stability, and extended breathing behavior.

Solvent- and anion-induced interconversions of metal-organic cages.

Fully structural interconversions between monomeric Pd24 and interlocked dimeric Pd48 cages have been investigated to elucidate their thermodynamic stability defined by their anion-guest binding behaviours.

Prognosis of acute-on-chronic liver failure patients treated with artificial liver support system.

AIM: To establish a new model for predicting survival in acute-on-chronic liver failure (ACLF) patients treated with an artificial liver support system. METHODS: One hundred and eighty-one ACLF patients who were admitted to the hospital from January 1, 2012 to December 31, 2014 and were treated with an artificial liver support system were enrolled in this retrospective study, including a derivation cohort (n = 113) and a validation cohort (n = 68). Laboratory parameters at baseline were analyzed and correlated with clinical outcome. In addition to standard medical therapy, ACLF patients underwent plasma exchange (PE) or plasma bilirubin adsorption (PBA) combined with plasma exchange. For the derivation cohort, Kaplan-Meier methods were used to estimate survival curves, and Cox regression was used in survival analysis to generate a prognostic model. The performance of the new model was tested in the validation cohort using a receiver-operator curve. RESULTS: The mean overall survival for the derivation cohort was 441 d (95%CI: 379-504 d), and the 90- and 270-d survival probabilities were 70.3% and 58.3%, respectively. The mean survival times of patients treated with PBA plus PE and patients treated with PE were 531 d (95%CI: 455-605 d) and 343 d (95%CI: 254-432 d), respectively, which were significantly different (P = 0.012). When variables with bivariate significance were selected for inclusion into the multivariate Cox regression model, number of complications, age, scores of the model for end-stage liver disease (MELD) and type of artificial liver support system were defined as independent risk factors for survival in ACLF patients. This new prognostic model could accurately discriminate the outcome of patients with different scores in this cohort (P < 0.001). The model also had the ability to assign a predicted survival probability for individual patients. In the validation cohort, the new model remained better than the MELD. CONCLUSION: A novel model was constructed to predict prognosis and accurately discriminate survival in ACLF patients treated with an artificial liver support system.

Recombinant adeno-associated virus-mediated transfer of shRNA against Notch3 ameliorates hepatic fibrosis in rats.

Liver fibrosis, a wound healing process following all kinds of liver injuries, is characterized by excessive deposition of extracellular matrix (ECM). Our previous study revealed that Notch3 might participate in liver fibrogenesis by regulating the activation of hepatic stellate cells (HSCs). The aim of this study was to assess the effects of Notch3 shRNA on hepatic fibrosis in a rat model induced by carbon tetrachloride (CCl4) and to clarify the mechanisms underlying those effects. Recombinant adeno-associated virus type 1 (rAAV1) vector carrying Notch3 shRNA (rAAV1-Notch3-shRNA) was generated and transferred to rat livers via the tail vein. The expression of Notch3, Jagged1, Hes1 and α-SMA were detected by real-time RT-PCR and immunofluorescence. The effects of rAAV1-Notch3-shRNA on fibrosis was investigated by pathological and immunohistochemical examination. Our findings showed that Notch3, Jagged1, Hes1 and α-SMA were downregulated. This downregulation was accompanied by improved hepatic fibrosis after the inhibition of Notch3 in vivo. rAAV1-Notch3-shRNA treatment reversed the epithelial-mesenchymal transition (EMT) in fibrotic livers by decreasing the expression of transforming growth factor ß1 (TGF-ß1) and vimentin in a line with the increased expression of E-cadherin. The inhibition of Notch3 was not found to play a role in hepatocyte proliferation. Rather, it inhibited hepatocyte apoptosis in vivo to some extent. The results of the present study suggest that the inhibition of Notch3 can protect hepatocytes from undergoing apoptosis and attenuate liver fibrogenesis. This may be a viable therapeutic option for hepatic fibrosis.

Synergistic anti-tumor effect of recombinant chicken fibroblast growth factor receptor-1-mediated anti-angiogenesis and low-dose gemcitabine in a mouse colon adenocarcinoma model.

AIM: To evaluate whether the combination of recombinant chicken fibroblast growth factor receptor-1 (FGFR-1) protein vaccine (cFR-1) combined with low-dose gemcitabine would improve anti-tumor efficacy in a mouse CT26 colon adenocarcinoma (CT26) model. METHODS: The CT26 model was established in BABL/c mice. Seven days after tumor cell injection, mice were randomly divided into four groups: combination therapy, cFR-1 alone, gemcitabine alone, and normal saline groups. Tumor growth, survival rate of tumor-bearing mice, and systemic toxicity were observed. The presence of anti-tumor auto-antibodies was detected by Western blot analysis and enzyme-linked immunospot assay, microvessel density (MVD) of the tumors and tumor cell proliferation were detected by Immunohistochemistry staining, and tumor cell apoptosis was detected by TdT-mediated biotinylated-dUTP nick end label staining. RESULTS: The combination therapy results in apparent decreases in tumor volume, microvessel density and tumor cell proliferation, and an increase in apoptosis without obvious side-effects as compared with either therapy alone or normal control groups. Also, both auto-antibodies and the antibody-producing B cells against mouse FGFR-1 were detected in mice immunized with cFR-1 vaccine alone or with combination therapy, but not in non-immunized mice. In addition, the deposition of auto-antibodies on endothelial cells from mice immunized with cFR-1 was observed by immunofluorescent stain-ing, but not on endothelial cells from control groups. Synergistic indexes of tumor volume, MVD, cell apoptosis and proliferation in the combination therapy group were 1.71 vs 1.15 vs 1.11 and 1.04, respectively, 31 d after tumor cell injection. CONCLUSION: The combination of cFR-1-mediated anti-angiogenesis and low-dose gemcitabine synergistically enhances the anti-tumor activity without overt toxicity in mice.