Synergistic effects of micro/nano modifications on electrodes for microfluidic electrochemical ELISA

Microfluidic electrochemical sensing has been considered to be highly efficient. However, we showed, by using numerical simulations in this study, that a planar electrode formed on the bottom of a microchannel is exposed to only a small fraction of analytes in amperometric detection. We also showed that three-dimensional (3D) micropillar electrodes significantly improve the detection current. The practical performance was evaluated using 3D micropillar electrodes fabricated by photolithography. The output current increased as the diameters of the micropillars decreased, as predicted by the simulations. It is noteworthy that the current enhancements obtained with the 3D electrodes were larger than those expected from an increase in the surface area. Further increase in current was achieved by electrical deposition of nanoporous gold-black onto the surface of the 3D electrode: when a 3D electrode with micropillars 30 μm in diameter was used, the output current was approximately 20 times that obtained with a 2D electrode without modification. The applicability of the micropillar electrodes was demonstrated in electrochemical enzyme-linked immunosorbent assay (ELISA) of bone metabolic marker proteins. Although an increase in the surface area of the electrode leads to more noise in general, there is no significant difference in the signal-to-noise ratio between the modified 3D electrode and the 2D electrode without modification in the ELISA experiments. This nanoporous micropillar electrode could potentially be a useful component for the development of on-site diagnosis systems.     

Slurry mixing device with microchannels for gelcasting

We developed a slurry mixing device with microchannels. Each channel has a width of 500 μm and a height of 75 μm with oblique ridges on the wall with the aim of rotating the slurry and enhancing the chaotic mixing efficiency. The effect of the oblique ridges on the slurry mixing efficiency was investigated for various ridge angles (30°, 45°, and 60°). We found that the slurry was successfully mixed by the channels with oblique ridges and that channels with a 45° ridge angle had the highest mixing efficiency.     

Enantioselective Hydrogenation of (E)-α-phenylcinnamic Acid over Cinchonidine-modified Pd Catalysts Supported on TiO2 and CeO2

The effects of the catalyst support, reaction temperature, and concentration of the modifier were examined to optimize supported Pd-catalysts and reaction conditions for the achievement of higher enantiomeric excess in the hydrogenation of (E)-α-phenylcinnamic acid. Over 90% of enantioselectivity was achieved using a cinchonidine-modified 40 wt% Pd/TiO₂ catalyst at 288 K.     

Ribosomal Synthesis of Cyclic Peptides with a Fluorogenic Oxidative Coupling Reaction

Ring around the peptides : We demonstrate a new method for the cyclization of peptides that involves the oxidative coupling of 5‐hydroxyindole and benzylamine. After two nonproteinogenic amino acids were incorporated into peptides by reprogramming the genetic code, cyclization took place rapidly upon the addition of K₃Fe(CN)₆ and generated a conjugated, fluorescent, heterocyclic structure.

     

Tissue Engineering: Scaffold‐Mediated 2D Cellular Orientations for Construction of Three Dimensionally Engineered Tissues Composed of Oriented Cells and Extracellular Matrices (Adv. Funct. Mater. 7/2009)

Various hydrogels, such as poly(γ‐glutamic acid) (γ‐PGA), gelatin (GT), alginic acid (Alg), and agarose (Aga), with 3D interconnected and oriented fibrous pores (OP gels) are prepared for 3D polymeric cellular scaffolds by using silica fiber cloth (SC) as template. After the preparation of these hydrogels with the SC templates, the latter are subsequently removed by washing with hydrofluoric acid solution. Scanning electron microscopy (SEM) clearly shows OP structures in the hydrogels. These various types of OP gels are successfully prepared in this way, independently of the crosslinking mechanism, such as chemical (γ‐PGA or GT), coordinate‐bonded (Alg), or hydrogen‐bonded (Aga) crosslinks. SEM, confocal laser scanning microscopy, and histological evaluations clearly demonstrate that mouse L929 fibroblast cells adhere to and extend along these OP structures on/in γ‐PGA hydrogels during 3D cell culture. The L929 cells that adhere on/in the oriented hydrogel are viable and proliferative. Furthermore, 3D engineered tissues, composed of the oriented cells and extracellular matrices (ECM) produced by the cells, are constructed in vitro by subsequent decomposition of the hydrogel with cysteine after 14 days of cell culture. This novel technology to fabricate 3D‐engineered tissues, consisting of oriented cells and ECM, will be useful for tissue engineering.     

Docosahexaenoic acid levels in the lipids of spotted mackerel Scomber australasicus

The lipid and FA compositions of various organs and of the stomach contents of Scomber australasicus were analyzed. DHA was characteristically the major FA of all the major lipid classes of all organs except for liver TAG. The mean DHA contents of the various organs accounted for more than 17% of the total FA (TFA), whereas those in the stomach contents, originating from the prey, fluctuated and were generally low. In particular, the DHA levels in the TAG from all organs of S. australasicus accounted for up to 17% of TFA, even though it is a neutral depot lipid. S. australasicus contained markedly high levels of DHA, even though it is a small-sized Scombridae species, and its high levels of DHA were close to those in large-sized highly migratory tuna species. Furthermore, DHA levels in its muscle TAG were consistently high, compared with those in the visceral TAG, which might be directly influenced by the prey lipids. These phenomena suggest that long-distance migration has a close relationship with high accumulation of DHA in fish tissues, since S. australasicus is reported to migrate in offshore water, similar to highly migratory tuna species. Additionally, the physiological selective accumulation of DHA in the muscle during migration is caused by in vivo metabolism of FA in the vascular system, suggesting that DHA is poorly used as a source of migration energy, though it is provided abundantly through the prey lipids.     

Solution-stirring method improves crystal quality of human triosephosphate isomerase

We examined the effect of a solution-stirring method on human triosephosphate isomerase crystallization. The crystals diffracted to more than 1.4 A resolution, whereas those obtained by the normal vapour-diffusion technique diffracted to 2.8 A. These results clearly show that the solution-stirring method is valuable and useful for protein crystallization because of its effectiveness and simplicity.