Isoreticular Contraction of Cage-like Metal-Organic Frameworks with Optimized Pore Space for Enhanced C2H2/CO2 and C2H2/C2H4 Separations.

The C2H2 separation from CO2 and C2H4 is of great importance yet highly challenging in the petrochemical industry, owing to their similar physical and chemical properties. Herein, the pore nanospace engineering of cage-like mixed-ligand MFOF-1 has been accomplished via contracting the size of the pyridine- and carboxylic acid-functionalized linkers and introducing a fluoride- and sulfate-bridging cobalt cluster, based on a reticular chemistry strategy. Compared with the prototypical MFOF-1, the constructed FJUT-1 with the same topology presents significantly improved C2H2 adsorption capacity, and selective C2H2 separation performance due to the reduced cage cavity size, functionalized pore surface, and appropriate pore volume. The introduction of fluoride- and sulfate-bridging cubane-type tetranuclear cobalt clusters bestows FJUT-1 with exceptional chemical stability under harsh conditions while providing multiple potential C2H2 binding sites, thus rendering the adequate ability for practical C2H2 separation application as confirmed by the dynamic breakthrough experiments under dry and humid conditions. Additionally, the distinct binding mechanism is suggested by theoretical calculations in which the multiple supramolecular interactions involving C-H···O, C-H···F, and other van der Waals forces play a critical role in the selective C2H2 separation.

Optimized Pore Nanospace through the Construction of a Cagelike Metal-Organic Framework for CO2/N2 Separation.

The development of metal-organic framework (MOF) adsorbents with a potential molecule sieving effect for CO2 capture and separation from flue gas is of critical importance for reducing the CO2 emissions to the atmosphere yet challenging. Herein, a cagelike MOF with a suitable cage window size falling between CO2 and N2 and the cavity has been constructed to evaluate its CO2/N2 separation performance. It is noteworthy that the introduction of coordinated dimethylamine (DMA) and N,N'-dimethylformamide (DMF) molecules not only significantly reduces the cage window size but also enhances the framework-CO2 interaction via C-H···O hydrogen bonds, as proven by molecular modeling, thus leading to an improved CO2 separation performance. Moreover, transient breakthrough experiments corroborate the efficient CO2/N2 separation, revealing that the introduction of DMA and DMF molecules plays a vital role in the separation of a CO2/N2 gas mixture.

Mechanism study of isoflavones as an anti-retinoblastoma progression agent.

Isoflavones, bioactive soy compounds, are known to exhibit anticancer activities. The present study investigated the anticancer activities of isoflavones on human retinoblastoma Y79 cells in vitro and in vivo. An MTT cell viability assay showed that the half maximal inhibitory concentration value of isoflavones against human retinoblastoma Y79 cells is 1.23 ± 0.42 µmol/l. Flow cytometry analysis indicated that isoflavones blocked G1/S progression. Western blot analysis demonstrated that the mammalian target of rapamycin (mTOR) pathway in Y79 cells was inhibited by isoflavones, with a concomitant decrease in cyclin E1, which accounted for the isoflavone-mediated G1 phase arrest. Isoflavones also inhibited human retinoblastoma growth in vivo; western blot analysis showed inhibition of mTOR and downregulation of cyclin E1 in an isoflavone-treated xenograft mouse model. Together, these results illustrate that isoflavones inhibit retinoblastoma tumour growth in vitro and vivo and that inactivation of the mTOR pathway and downregulation of cyclin E1 is involved in this action. The results of this study suggest that isoflavones could be tested as promising anti-retinoblastoma agent.

Structure-function relationship of conotoxin lt14a, a potential analgesic with low cytotoxicity.

A novel conotoxin lt14a containing 13 amino acid residues with an amidated C-terminus derived from Conus litteratus, belongs to C-C-C-C cysteine pattern. As the smallest peptide of conotoxin framework 14, lt14a could inhibit nicotinic acetylcholine receptor and suppress pain. To elucidate structure-function relationship, we determine the solution structure by NMR and find that lt14a comprises a short duple ß-strand region and ß-turn motif. An analog [K7A]-lt14a of Ala substitution for Lys in position 7 is designed. Interestingly, [K7A]-lt14a exhibits higher activity than lt14a as long-lasting analgesic in the hotplate pain model in mice. Additionally, MTT assay reveals that the two peptides have low toxicity to human cells. The studies suggest that positively charged residue may not be involved in the blocking mechanism. However, due to the Ala substitution, hydrophobic residues' patch expansion strengthens the binding ability. A hypothesis is given that in conotoxin lt14a, hydrophobic residues rather than charged residues play a key role during target binding.

Identification of a novel M-superfamily conotoxin with the ability to enhance tetrodotoxin sensitive sodium currents.

In this work, a novel M-superfamily conotoxin, designated lt3a, was purified from the crude venom of Conus litteratus. Combined with peptide sequencing, MALDI-TOF mass spectrometry and cDNA cloning techniques, the amino acid sequence of lt3a was supposed to be DgammaCCgamma OQWCDGACDCCS, where O is hydroxyproline and gamma is carboxyglutamate. The Cys framework of lt3a (-CC-C-C-CC-) is similar to that of psi-, mu-, kappaM-conotoxins, which are representatives of M-conotoxins. Peptide lt3a is categorized into M1 branch based on the number of residues in the last Cys loop. Whole cell patch-clamp study on adult rat dorsal root ganglion neurons indicated that lt3a could enhance tetrodotoxin-sensitive sodium currents. This is a previously unknown function of M-superfamily conotoxins.