1,721,282 research outputs found
Modulation of transmembrane anion transport of porphyrin boxes by dynamic window size engineering
No full textThe development of synthetic transmembrane anion transport systems is of considerable interest, not only for mimicking the functions of natural transmembrane proteins but also for practical applications. We have recently reported a porous organic cage, porphyrin box (PB(8)) having multiple windows surrounded by octyl chains as an iodide selective anion channel. Herein, we report the modulation of transmembrane transport of halides (Cl-, Br-, and I-) by dynamic window size engineering of the cage with different alkyl chain lengths (hexyl PB(6), octyl PB(8) and decyl PB(10)). 'Apparent' transport rates were measured by the HPTS fluorescence assay, which shows a gradual decrease in the transport rate upon increasing the length of alkyl chains of PB. We calculate the transport rate per PB in order to make a fair comparison as the 'apparent' transport rate is proportional to the number of PBs embedded in the lipid membrane. The transport rate per PB reveals that increasing the length of the alkyl chains of PBs results in a substantial fall in the iodide transport rate while only marginally decreasing the transport rates of bromide and chloride, thereby decreasing the selectivity of iodide transport. © 2022 World Scientific Publishing Company.11Nsciescopu
Permselective 2D-polymer-based membrane tuneable by host-guest chemistry
No full textA permselective membrane with a non-covalently tailorable surface has been fabricated by deposition of a cucurbit[6]uril-based 2D polymer film onto a simple support membrane. Tuneable permselectivity of this membrane has been achieved through non-covalent surface modification using the remarkable host–guest chemistry of the incorporated cucurbit[6]uril units. © The Royal Society of Chemistry 20161111sciescopu
Structural Control of Metal–Organic Framework Bearing N‑Heterocyclic Imidazolium Cation and Generation of Highly Stable Porous Structure
No full textBuilding a well-defined porous structure
with permanent porosity
in a metal–organic framework (MOF) is significant to achieve
selective adsorption of guest molecules and its practicality. There
have been various efforts to develop new functional frameworks, but
chasing both advantages (functions and stability) is always challenging.
Herein, we report a highly stable and porous 3D MOF having an imidazolium
group. By adjusting counteranions of the imidazolium group, we could
prepare two distinct MOFs. The 2D MOF constructed by applying bicarbonate
anion inhibited three-dimensional growth and showed N2 adsorption
with BET results of 330 m2/g. However, the 3D MOF (Imi-3D) formed by applying chloride anion on the imidazolium
group evolved into a 4-fold interpenetrated cube structure. The Imi-3D has high porosity in spite of the folded nature of
the structure, with BET results of 1400 m2/g. Interestingly,
unlike the usual trend of unstable zinc carboxylate based MOFs, the
multiple π–π interactions of the Imi-3D presents a unique tolerance toward various solvents, especially
toward water, for 6 months and without decomposition or collapse of
the framework. Moreover, since the
porous 3D MOF consists of imidazolium groups, the MOF shows a cationic
feature with strong adsorption toward anionic guests in aqueous media
The guest-dependent thermal response of the flexible MOF Zn2(BDC)2(DABCO)
No full textThe guest-dependent thermal response of the flexible MOF Zn2(BDC)2(DABCO) (1) has been studied. A series of temperature-dependent single crystallographic analyses revealed inherent structural thermal responses of 1. The guest-free framework 1 exhibited interesting thermal responses including anisotropic thermal expansion (negative thermal expansion (NTE) along the a- and b-axes, positive thermal expansion (PTE) along the c-axis) and disorder-order phase transition. In addition, inclusion of guest molecules (DMF and benzene) brought distinct thermal responses to 1 from host-guest interactions. 1·4DMF showed altered thermal responses, presenting disorder-order phase transitions at a higher temperature and PTE along the a- and b-axes. Meanwhile, 1·3benzene displayed a quite different type of thermal response such as a hinge like motion (breathing) without a symmetry change. © The Royal Society of Chemistry 2016114171sciescopu
Pseudomorphic transformation of iron-based microporous metal-organic frameworks to mesoporous iron phosphate
No full textA facile pseudomorphic transformation of microporous iron-based metal-organic frameworks (MOFs) into mesoporous iron(III) phosphate is described. Simple soaking of MIL-100(Fe) in the phosphate buffer solution produces mesopomus FePO4, with an average pore size of similar to 10 nm as characterized by ICP, IR, Raman, XPS, PXRD and gas sorption measurements. The most remarkable feature of this MOF-mediated synthetic method is the generation of mesoporous FePO4 with a narrow pore size distribution and high pore volume under mild conditions (at near neutral pH and room temperature) while maintaining the original MOF morphology, which may find useful applications in many areas including catalysis and energy storage.11Nsciescopu
Stepwise synthesis via mechanochemical reaction for multistate redox-active 2D Zinc(ii) coordination network
No full textA multistate redox-active coordination network was prepared by stepwise synthesis via mechanochemical reaction to overcome the low solubility of ligands. Solid-state grinding between sparingly soluble ligands and metal ions lead to the formation of a soluble intermediate. A two-dimensional (2D) coordination network possessing open channels and iodinated pores was prepared by using the intermediate. The redox activity of the network, which was derived from ligands, was confirmed by electron spin resonance (ESR) spectroscopy and solid-state cyclic voltammetry. © 2018 The Chemical Society of Japa
Deciphering the Specific High-Affinity Binding of Cucurbit[7]uril to Amino Acids in Water
No full textThis work presents a systematic study on the host-guest interactions between the macrocyclic host molecule cucurbit[7]uril (CB[7]) and amino acids (AAs) including three basic AAs (Lys, Arg, and His) and three aromatic AAs (Phe, Tyr, and Trp) to elucidate the origin of the high selectivity of CB[7] toward AA residues in proteins. Complex formation between CB[7] and each AA was examined in solution (by isothermal titration calorimetry and NMR) as well as in the gas phase (by ion mobility mass spectrometry and collision-induced dissociation), and the results were further combined with computational investigations. Generally, the aromatic AAs show higher binding affinities than the basic AAs in buffer solutions with various pH values. On the contrary, the gas-phase stabilities of the basic AA complex ions are higher than those of the aromatic AA complex ions, suggesting that the direct ion-dipole interactions between the charged side chains of the basic AAs and the polar carbonyl groups of CB[7] predominate in the absence of water. The ion-dipole interactions are less significant in water, since the original interactions of the guests with water are lost upon complex formation. In contrast, the transfer of the hydrophobic groups from the bulk into the hydrophobic CB[7] cavity suffers less from the desolvation penalty, resulting in higher binding affinities in water. Therefore, initial guest solvation is another key factor which should be considered when designing high-affinity host-guest systems, in addition to the contribution from the release of high-energy water molecules from the CB[7] cavity (J. Am. Chem. Soc. 2012, 134, 15318-15323). (Chemical Equation Presented). © 2015 American Chemical Society136341sciescopu
Supramolecular hydrogels for long-term bioengineered stem cell therapy
No full textSynthetic hydrogels have been extensively investigated as artifi cial extracellular
matrices (ECMs) for tissue engineering in vitro and in vivo. Crucial
challenges for such hydrogels are sustaining long-term cytocompatible encapsulation
and providing appropriate cues at the right place and time for spatiotemporal
control of the cells. Here, in situ supramolecularly assembled and
modularly modifi ed hydrogels for long-term engineered mesenchymal stem
cell (eMSC) therapy are reported using cucurbit[6]uril-conjugated hyaluronic
acid (CB[6]-HA), diaminohexane conjugated HA (DAH-HA), and drug-conjugated
CB[6] (drug-CB[6]). The eMSCs producing enhanced green fl uorescence
protein (EGFP) remain alive and emit the fl uorescence within CB[6]/DAH-HA
hydrogels in mice for more than 60 d. Furthermore, the long-term expression
of mutant interleukin-12 (IL-12M) by eMSCs within the supramolecular
hydrogels results in effective inhibition of tumor growth with a signifi cantly
enhanced survival rate. Taken together, these fi ndings confi rm the feasibility
of supramolecular HA hydrogels as 3D artifi cial ECMs for cell therapies and
tissue engineering applications.120201sciescopu
Identification of mitochondrial proteins associated with cyanine 5 using a combination of affinity-based photocrosslinking with bio-orthogonal supramolecular latching
No full textVisualization of mitochondria with cyanine dyes has been exploited to study the functions of mitochondria. However, proteins interacting with cyanine dyes have not been investigated clearly. Here, we report a chemical proteomics approach for the identification of mitochondrial proteins associated with cyanine dyes. This approach uses affinity-based photocrosslinking of Cy5-diazirine-alkyne (Cy5-DAyne) in combination with selective enrichment of target proteins by bio-orthogonal supramolecular latching based on unique host-guest interaction between cucurbit[7]uril (CB[7]) and its selected guest such as adamantylammonium (AdA). The enriched proteins then were analyzed using LC-MS/MS to provide a list of proteins closely associated with the Cy5 motif. This study suggests that the proteomic environment around the Cy5 motif is highly associated with energy production processes, including the respiratory chain, ATP synthesis, and fatty acid oxidization. Moreover, it demonstrates the potential of this chemical proteomic approach for the investigation of other organellar proteins using different selective dyes.11Nsciescopu
A facile preparation method for nanosized MOFs as a multifunctional material for cellular imaging and drug delivery
No full textTb-based metal-organic framework nanoparticles (Tb-MOF NPs) with good colloidal stability and stable fluorescence properties in an aqueous solution were prepared by a simple mechanical grinding of Tb-MOF with a biocompatible polymer surfactant (F127). The characteristic fluorescence property of Tb-MOF NPs allowed us to use this nanomaterial as a cell imaging probe. Efficient cellular uptake of Tb-MOF NPs apparently via an energy-dependent endocytosis was observed by confocal laser scanning microscopy. By taking advantage of the porous nature of the Tb-MOF NPs an anticancer drug (doxorubicin) was successfully loaded and delivered to kill cancer cells to demonstrate their usage as a drug delivery vehicle. This simple grinding method afforded a nanosized, multifunctional biomaterial that was used for cell imaging and drug delivery, and it can be extended to other MOFs to widen their applications.</p
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