Specific Cell Surface Protein Imaging by Extended Self-Assembling Fluorescent Turn-on Nanoprobes

Visualization of tumor-specific protein biomarkers on cell membranes has the potential to contribute greatly to basic biological research and therapeutic applications. We recently reported a unique supramolecular strategy for specific protein detection using self-assembling fluorescent nanoprobes consisting of a hydrophilic protein ligand and a hydrophobic BODIPY fluorophore in test tube settings. This method is based on recognition-driven disassembly of the nanoprobes, which induces a clear turn-on fluorescent signal. In the present study, we have successfully extended the range of applicable fluorophores to the more hydrophilic ones such as fluorescein or rhodamine by introducing a hydrophobic module near the fluorophore. Increasing the range of available fluorophores allowed selective imaging of membrane-bound proteins under live cell conditions. That is, overexpressed folate receptor (FR) or hypoxia-inducible membrane-bound carbonic anhydrases (CA) on live cell surfaces as cancer-specific biomarkers were fluorescently visualized using the designed supramolecular nanoprobes in the turn-on manner. Moreover, a cell-based inhibitor-assay platform for CA on a live cell surface was constructed, highlighting the potential applicability of the self-assembling turn-on probes.     

Inclusion and dielectric properties of a vinylidene fluoride oligomer in coordination nanochannels

The dynamics of oligo(vinylidene fluoride) (OVDF) confined in regular nanochannels of a porous coordination polymer (PCP) was studied by means of dielectric spectroscopy. The OVDF chains in the PCP nanopores showed two Arrhenius-type relaxation processes at lower temperatures than the relaxation temperature observed for the neat OVDF, showing the enhanced mobility of the confined OVDF.     

Size-selected copper oxide nanoparticles synthesized by laser ablation

Size-tuned copper oxide nanoparticles with sizes of 9, 12, and 15 nm were fabricated by laser ablation and on-line size selection using a differential mobility analyzer at a gas pressure of 666 Pa. The dependence of the particle properties on the in situ annealing temperatures and selection sizes was investigated. The crystalline phases of the nanoparticles fabricated at temperatures below 973 K were assigned to monoclinic cupric oxide (CuO) which converted into cubic cuprous oxide (Cu₂O) when the annealing temperature was above 1,173 K. This indicates that the crystalline phases can be easily controlled by changing the annealing temperature. TEM images confirmed that well-crystallized and well-dispersed CuO and Cu₂O nanoparticles with narrow size distributions were obtained using this method. This fabrication process is useful and promising for the future investigation of the intrinsic size-dependent properties of CuO and Cu₂O.     

Coulombic aggregations of Mn(III) salen-type complexes and Keggin-type polyoxometalates: isolation of Mn2 single-molecule magnets

The reaction of Mn(III) salen-type complexes with di- and tetraanionic α-Keggin-type polyoxometalates (POMs) was performed, and three types of Coulombic aggregations containing Mn(III) out-of-plane dimeric units (abbreviated as [Mn(2)](2+)) that are potentially single-molecule magnets (SMMs) with an S(T) = 4 ground state were synthesized: [Mn(2)(5-MeOsaltmen)(2)(acetone)(2)][SW(12)O(40)] (1), [Mn(2)(salen)(2)(H(2)O)(2)](2)[SiW(12)O(40)] (2), and [Mn(5-Brsaltmen)(H(2)O)(acetone)](2)[{Mn(2)(5-Brsaltmen)(2)}(SiW(12)O(40))] (3), where 5-Rsaltmen(2-) = N,N'-(1,1,2,2-tetramethylethylene)bis(5-R-salicylideneiminate) with R = MeO (methoxy), Br (bromo) and salen(2-) = N,N'-ethylenebis(salicylideneiminate). Compound 1 with a dianionic POM, [SW(12)O(40)](2-), is composed of a 1:1 aggregating set of [Mn(2)](2+)/POM, and 2, with a tetraanionic POM, [SiW(12)O(40)](4-), is a 2:1 set. Compound 3 with [SiW(12)O(40)](4-) forms a unique 1D coordinating chain with a [-{Mn(2)}-POM-](2-) repeating unit, for which a hydrogen-bonded dimeric unit ([Mn(5-Brsaltmen)(H(2)O)(acetone)](2)(2+)) is present as a countercation. Independent of the formula ratio of [Mn(2)](2+)/POM, Mn(III) dimers and POM units in 1-3 form respective segregated columns along a direction of the unit cell, which make an alternate packing to separate evenly identical species in a crystal. The nearest intermolecular Mn···Mn distance is found in the order 2 < 3 < 1. The segregation of the [Mn(2)](2+) dimer resulted in interdimer distances long enough to effectively reduce the intermolecular magnetic interaction, in particular in 1 and 3. Consequently, an intrinsic property, SMM behavior, of Mn(III) dimers has been characterized in this system, even though the interdimer interactions are still crucial in the case of 2, where a long-range magnetic order competitively affects slow relaxation of the magnetization at low ac frequencies.     

In Situ Tracking of Dynamic NO Capture through a Crystal-to-Crystal Transformation from a Gate-Open-Type Chain Porous Coordination Polymer to a NO-Adducted Discrete Isomer

Optimal control of gas adsorption properties in metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) remains a great challenge in the field of materials science. An efficient strategy to capture electron-acceptor-type gas molecules such as nitrogen monooxide (NO) is to use host–guest interactions by utilizing electron-donor-type MOFs/PCPs as host frameworks. Herein, we focus on a highly electron-donating chain compound by using the paddlewheel-type [Ru₂^II,II] complex [Ru₂(2,4,5-Me₃PhCO₂)₄] (2,4,5-Me₃PhCO₂⁻=2,4,5-trimethylbenzoate) with the phenazine (phz) linker: [Ru₂(2,4,5-Me₃PhCO₂)₄(phz)] ( 1 ). Compound 1 exhibited a specific gated adsorption for NO under gas pressures greater than 60 kPa at 121 K, which finally resulted in approximately seven molar equivalents being taken up at 100 kPa followed by four molar equivalents remaining under vacuum at 121 K; its Rh isomorph ( 2 ) with weaker donation ability was inactive for NO. When the sample of 1 ⊃4 NO was heated to room temperature, the compound underwent a crystal-to-crystal phase transition to give [Ru₂(2,4,5-Me₃PhCO₂)₄(NO)₂](phz) ( 1 -NO), involving a post-synthetic nitrosylation on the [Ru₂] unit, accompanied by an eventful site-exchange with phz. This drastic event, which is dependent on the NO pressure, temperature, and time, was coherently monitored by using several different in situ techniques, revealing that the stabilization of NO molecules in nanosized pores dynamically and stepwisely occurred with the support of strong electronic/magnetic host–guest interactions.     

Convection-Flow-Assisted Preparation of a Strong Electron Dopant,Benzyl Viologen,for Surface-Charge Transfer Doping of Molybdenum Disulfide

Transition metal dichalcogenides (TMDCs) have received attention as atomically thin post-silicon semiconducting materials. Tuning the carrier concentrations of the TMDCs is important, but their thin structure requires a non-destructive modulation method. Recently, a surface-charge transfer doping method was developed based on contacting molecules on TMDCs, and the method succeeded in achieving a large modulation of the electronic structures. The successful dopant is a neutral benzyl viologen (BV⁰); however, the problem remains of how to effectively prepare the BV⁰ molecules. A reduction process with NaBH₄ in water has been proposed as a preparation method, but the NaBH₄ simultaneously reacts vigorously with the water. Here, a simple method is developed, in which the reaction vial is placed on a hotplate and a fragment of air-stable metal is used instead of NaBH₄ to prepare the BV⁰ dopant molecules. The prepared BV⁰ molecules show a strong doping ability in terms of achieving a degenerate situation of a TMDC, MoS₂. A key finding in this preparation method is that a convection flow in the vial effectively transports the produced BV⁰ to a collection solvent. This method is simple and safe and facilitates the tuning of the optoelectronic properties of nanomaterials by the easily-handled dopant molecules.     

Thermotropic liquid crystalline ionic stilbazoles and their miscible mixtures with non-ionic carbazolyl compounds

New thermotropic ionic liquid crystals were prepared from trans-4-nitro-4'-stilbazole and alkyl halides. trans-N-Alkyl-4-nitro-4'-stilbazolium bromides containing alkyl chains with 7 to 10 carbons and the chloride homologues containing alkyl chains with 5 to 10 carbons exhibited smectic phases. For example, trans-N-decyl-4-nitro-4'-stilbazolium bromide and trans-N-hexyl-4-nitro-4'-stilbazolium chloride showed smectic phases from 175 to 186°C and from 129 to 190°C, respectively. The temperature range of mesophases increased with decreasing size of the counteranions. The miscibility of trans-N-alkyl-4-nitro-4'-stilbazolium bromide in Schiff's base compounds having various electronegative groups was examined by differential scanning calorimetry and polarizing microscopy. Miscible binary mixtures were prepared from trans-N-alkyl-4-nitro-4'-stilbazolium bromides and 4-alkoxy-N-(9-methyl-2-carbozolyl-methylene)anilines. The 1:1 (mole ratio) binary mixture of trans-N-hexyl-4-nitro-4'-stilbazolium bromide with 4-hexyloxy-N-(9-methyl-2-carbazolylmethylene)aniline exhibited a stable smectic phase between 83 and 149°C, though a smectic phase is not exhibited by both individual components. The miscibility in the binary mixtures might be caused by a combination of ionic and electron donor-acceptor interactions.     

Complete removal of paint from metal surface by ablation with a TEA CO2 laser

For high-speed metal surface cleaning, we applied TEA CO₂ laser pulses to ablate painted materials on metal surfaces and examined the efficiency of removal under different surface and irradiation conditions. Surfaces treated with a line-focused laser beam were analyzed with an energy dispersive X-ray analyzer and inspected with optical microscopic observation. Although paints were selectively ablated from the metal surface, the cleaning efficiency was found to depend on surface conditions of substrates. An application of a small amount of dimethyl formamide was effective for completely removing of resin without scorching the surface.     

Pd(O) promoted transformation of N-tosyl-2-(1,3-butadienyl)-aziridine into N-tosyl-2-vinyl-3-pyrroline

1,3-Butadienylaziridines activated by N-tosyl group smoothly rearrange to vinylpyrrolidine derivatives in the presence of a catalytic amount of Pd(PPh₃)₄. Transformation of dienylazetidines into vinylpiperidine derivatives is also described.