Novel combination of hydrophilic/hydrophobic surface for large wettability difference and its application to liquid manipulation

This paper reports a novel combination of hydrophilic/hydrophobic materials for the evolution of liquid manipulation. Droplet generation based on a hydrophilic/hydrophobic mechanism is a promising method for highly accurate liquid manipulations. Although several droplet manipulation devices utilizing hydrophilic/hydrophobic patterns have been reported, it has been difficult to split fluid into droplets solely through hydrophilic/hydrophobic patterns in a microchannel. In this study, a material combination for fabricating hydrophilic/hydrophobic patterns was investigated and their wettability difference was enhanced for droplet generation. To improve hydrophilicity, we attempted to increase the surface area of silicon oxide through pulsed plasma chemical vapor deposition (PPCVD). To improve hydrophobicity, the damage to the hydrophobic patterns in the fabrication process was reduced. We successfully enhanced the difference in contact angles from 54.3° to 86.6° by combining the developed hydrophilic material and hydrophobic material. The developed material combination could successfully split fluid into a quantitative droplet of 14.1 nL in a microfluidic chip. Because the developed hydrophilic/hydrophobic combination enables the formation of a droplet with desirable shape in microchannels, the developed hydrophilic/hydrophobic combination is a promising component for lab-on-a-chip applications.     

In situ synthesis and photoresponsive rupture of organosilica nanocapsules

This communication describes in situ synthesis of thiocyanato-functionalized organosilica nanocapsules by a sol-gel reaction using 3-thiocyanatopropyltriethoxysilane as a precursor. Moreover, the nanocapsules are photoresponsive and burst under light irradiation, resulting in release of the encapsulated drug or dye.     

Size-controlled long-circulating PICsome as a ruler to measure critical cut-off disposition size into normal and tumor tissues

Selective disposition of nanocarriers into target tissue is an essential issue in drug delivery. Critical size of nanocarriers (～150 nm) discriminating the permeability into normal and tumor tissues was determined by the use of size-tunable, polyion complex hollow vesicles (PICsome) as a ruler.     

Synthesis of indolequinones via a Sonogashira coupling/cyclization cascade reaction

A mild strategy for constructing indolequinone motifs is described on the basis of the Sonogashira reaction and a copper-catalyzed intramolecular cyclization cascade reaction. The first step involves the palladium- and copper-catalyzed reaction between halogenated naphthoquinone and terminal acetylene to generate a coupling product, which then reacts in a copper-catalyzed intramolecular cyclization with the nitrogen functional group adjacent to the carbon-carbon triple bond.     

Optimizing coverage of metal oxide nanoparticle prepared by pulsed laser deposition on nonenzymatic glucose detection

Metal oxide nanoparticles prepared by pulsed laser deposition (PLD) were applied to nonenzymatic glucose detection. NiO nanoparticles with size of 3 nm were deposited on glassy carbon (GC) and silicon substrates at room temperature in an oxygen atmosphere. Transmission electron microscope (TEM) image showed nanoparticles with the size of 3 nm uniformly scattered on the Si(0 0 1) substrate. Unlike co-sputtering nanoparticle and carbon simultaneously, the PLD method can easily control the surface coverage of nanoparticles on the surface of substrate by deposition time. Cyclic voltammetry was performed on the samples deposited on the GC substrates for electrochemical detection of glucose. The differences between peak currents with and without glucose was used to optimize the coverage of nanoparticles on carbon electrode. The results indicated that optimal coverage of nanoparticles on carbon electrode.     

Dislocations in silicon observed by high-voltage,high-resolution electron microscopy

Dislocations in deformed silicon crystals have been studied by high-resolution electron microscopy with the axial illumination along the [110] direction using a 1 MV electron microscope. Extended 60 dislocations, Z-shape faulted dipoles and stacking fault tetrahedra were observed in atomic level. The results demonstrated the potentiality of highvoltage, high-resolution electron microscopy for the study of atomic configurations of structural defects.     

Chemical modification of hydroxyl groups of poly(vinyl alcohol) by a glycosidation reaction

A new procedure for chemical modification of poly(vinyl alcohol) (PVA) was established by a glycosidation reaction of hydroxyl groups in PVA with triacetylated sugar oxazoline 1 . ¹H and ¹³C NMR analyses indicated that triacetylated N‐acetyl‐D‐glucosamine (GlcNAc) was introduced onto a PVA backbone selectively via a β‐O‐glycoside linkage. Deacetylation of triacetylated GlcNAc‐substituted PVA 2 resulted in GlcNAc‐substituted PVA 3 in good yield. These modified PVAs 2 and 3 exhibited solubilities and thermal properties different from the original PVA.     

Synthesis and optical properties of new conjugated polymers composed of 1,3,4‐thiadiazole and 2,5‐dialkoxybenzene rings

Intramolecular cyclization of precursor polyhydrazides derived from hydrazine and four 2,5‐dialkoxyterephthalic acids by direct polycondensation with Lawesson's reagent afforded new conjugated polymers constituted of 1,3,4‐thiadiazole and 2,5‐dialkoxybenzene units. The polymers emitted bluish green light in solution and green light in solid state in spite of the coexistence of non‐cyclized hydrazide linkage in the backbones, the Stokes shifts being 91–138 nm in the solid state. It was suggested that these polymers have appropriate lengths of conjugation backbones based on the 1,3,4‐thiadiazole moiety.