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.     

Star-shaped trimeric quaternary ammonium bromide surfactants: adsorption and aggregation properties

Novel star-shaped trimeric surfactants consisting of three quaternary ammonium surfactants linked to a tris(2-aminoethyl)amine core were synthesized. Each ammonium had two methyls and a straight alkyl chain of 8, 10, 12, or 14 carbons. The adsorption and aggregation properties of these tris(N-alkyl-N,N-dimethyl-2-ammoniumethyl)amine bromides (3C(n)trisQ, in which n represents alkyl chain carbon number) were characterized by equilibrium and dynamic surface tension, rheology, small-angle neutron scattering (SANS), and cryogenic transmission electron microscopy (cryo-TEM) techniques. 3C(n)trisQ showed critical micelle concentrations (CMC) 1 order of magnitude lower than that of the corresponding gemini surfactants with an ethylene spacer and the corresponding monomeric surfactants. The logarithm of the CMC decreased linearly with increasing hydrocarbon chain length for 3C(n)trisQ. The slope of the line, which is well-known as Klevens equation, was larger than those of the monomeric and gemini surfactants; however, considering the total carbon number in the chains, the slope was shallower than the monomeric and was close to the gemini. Through the results such as surface tensions at the CMC (32-34 mN m(-1)) and the parameters of standard free energy, CMC/C(20) and pC(20), it was found that 3C(n)trisQ could adsorb densely at the air/water interface despite the strong electrostatic repulsion between multiple quaternary ammonium headgroups. Moreover, dynamic surface tension measurements showed that the kinetics of adsorption for 3C(n)trisQ to the air/water interface was slow because of their bulky structures. Furthermore, the results of rheology, SANS, and cryo-TEM determined that 3C(n)trisQ with n = 10 and 12 formed ellipsoidal micelles at low concentrations in solution and the structures transformed to threadlike micelles with very few branches for n = 12 as the concentration increased, but for n = 14 threadlike micelles formed at relatively low concentrations.     

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.     

Synthesis and in vitro antifungal activities of novel triazole antifungal agent CS-758.

Synthesis and in vitro antifungal activities of a novel triazole antifungal agent CS-758 (former name, R-120758) are described. The minimum inhibitory concentrations (MICs) of a series of dioxane-triazole compounds related to R-102557 were examined. Variation of the length of the chain between the dioxane ring and the phenyl ring revealed that the linkage with two double bonds is the most preferable. When a cyano group was introduced to the C4 position on the benzene ring, MICs improved further. A fluorine atom was introduced to obtain CS-758. The MICs of CS-758 surpassed those of fluconazole and itraconazole against Candida, Aspergillus and Cryptococcus species. The precursor (E,E)-aldehyde was synthesized stereoselectively from 3-fluoro-4-methylbenzonitrile using the Horner-Wadsworth-Emmons reaction.     

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.     

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.     

Inhomogeneity control in polymer gels

Inhomogeneities, that is, nonrelaxing frozen concentration fluctuations, are inevitably present in polymer gels because they are introduced during the crosslinking of the constituent polymer chains in a solvent. Therefore, inhomogeneities increase as the number of crosslinks increases in a gel. The ionization of polymer gels is one of the methods used to suppress inhomogeneities. However, because crosslinking also means a freezing‐in of the conformation and topology of polymer chains in a solvent according to the chemistry of crosslinking, inhomogeneity control is quite sophisticated. In this article, we discuss the relationship between the inhomogeneities and the molecular/environmental parameters of polymer gels, such as the polymer concentration, the degree of crosslinking, the degree of ionization, and the interaction parameter, by considering the memory effect of gels. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 617–628, 2005     

Reaction of a diphosphene with various halogens

Bis(2,4,6-tri-$\text{tert}$-butylphenyl) diphosphene reacts with various halogens to give the corresponding phosphoric dihalides, haloarene, and arene depending upon the halogen and solvent used.