Microenvironmental Analysis and Control for Local Cells under Confluent Conditions via a Capillary-Based Microfluidic Device.

Sophisticated functions of biological tissues are supported by small biological units of cells that are localized within a region of 100 μm scale. The cells in these units secrete molecules to form their microenvironment to play a vital role in biological functions. Various microfluidic devices have been developed to analyze the microenvironment but were not designed for cells in a culture dish in a confluent condition, a typical setup for cell and tissue cultivation.

Bio-actuated microvalve in microfluidics using sensing and actuating function of Mimosa pudica.

Bio-actuators and sensors are increasingly employed in microscale devices for numerous applications. Unlike other artificial devices actuated by living cells or tissues, here we introduce a microvalve system actuated by the stimuli-responsive action plant, Mimosa pudica (sleepy plant). This system realizes the control of the valve to open and close by dropping and recovering responses of Mimosa pudica branch upon external physical stimulations.

Recent advances in microfluidic devices for single-cell cultivation: methods and applications.

Single-cell analysis is essential to improve our understanding of cell functionality from cellular and subcellular aspects for diagnosis and therapy. Single-cell cultivation is one of the most important processes in single-cell analysis, which allows the monitoring of actual information of individual cells and provides sufficient single-cell clones and cell-derived products for further analysis. The microfluidic device is a fast-rising system that offers efficient, effective, and sensitive single-cell cultivation and real-time single-cell analysis conducted either on-chip or off-chip.

A simple and reversible glass-glass bonding method to construct a microfluidic device and its application for cell recovery.

Compared with polymer microfluidic devices, glass microfluidic devices have advantages for diverse lab-on-a-chip applications due to their rigidity, optical transparency, thermal stability, and chemical/biological inertness. However, the bonding process to construct glass microfluidic devices usually involves treatment(s) like high temperature over 400 °C, oxygen plasma or piranha solution. Such processes require special skill, apparatus or harsh chemicals, and destroy molecules or cells in microchannels.

A sub-population of Dictyostelium discoideum cells shows extremely high sensitivity to cAMP for directional migration.

The chemotaxis of Dictysotelium discoideum cells in response to a chemical gradient of cyclic adenosine 3',5'-monophosphate (cAMP) was studied using a newly designed microfluidic device. The device consists of 800 cell-sized channels in parallel, each 4 μm wide, 5 μm high, and 100 μm long, allowing us to prepare the same chemical gradient in all channels and observe the motility of 500-1000 individual cells simultaneously. The percentage of cells that exhibited directed migration was determined for various cAMP concentrations ranging from 0.

A Microfluidic Platform Based on Robust Gas and Liquid Exchange for Long-term Culturing of Explanted Tissues.

Microfluidic devices are important platforms to culture and observe biological tissues. Compared with conventional setups, microfluidic devices have advantages in perfusion, including an enhanced delivery of nutrients and gases to tissues. However, explanted tissues can maintain their functions for only hours to days in microfluidic devices, although their observations are desired for weeks.

Ultrasensitive Single Cell Metabolomics by Capillary Electrophoresis-Mass Spectrometry with a Thin-Walled Tapered Emitter and Large-Volume Dual Sample Preconcentration.

Single cell metabolome analysis is essential for studying microscale life phenomena such as neuronal networks and tumor microenvironments. Capillary electrophoresis-mass spectrometry (CE-MS) is one of the most sensitive technologies; however, its sensitivity is still not enough for single cell analysis on general human cells such as HeLa. To address these issues, we first developed an efficient ionization emitter, named as a "nanoCESI" emitter, that had a thin-walled (∼10 μm) and tapered (5-10 μm) end.

Isolating Single Cells by Glass Microfluidics for Raman Analysis of Paramylon Biogenesis.

Time-course analysis of single cells is important to characterize heterogeneous activities of individual cells such as the metabolic response to their environment. Single-cell isolation is an essential step prior to time-course analysis of individual cells by collecting, culturing, and identifying multiple single-cell targets. Although single-cell isolation has been performed by various methods previously, a glass microfluidic device with semiclosed microchannels dramatically improved this process with its simple operation and easy transfer for time-course analysis of identified single cells.

Enhancement in acoustic focusing of micro and nanoparticles by thinning a microfluidic device.

The manipulation of micro/nanoparticles has become increasingly important in biological and industrial fields. As a non-contact method for particle manipulation, acoustic focusing has been applied in sorting, enrichment and analysis of particles with microfluidic devices. Although the frequency and amplitude of acoustic waves and the dimensions of microchannels have been recognized as important parameters for acoustic focusing, the thickness of microfluidic devices has not been considered so far.

Simple Isolation of Single Cell: Thin Glass Microfluidic Device for Observation of Isolated Single Euglena gracilis Cells.

Single cell analysis has gained attention as a means to investigate the heterogeneity of cells and amplify a cell with desired characteristics. However, obtaining a single cell from a large number of cells remains difficult because preparation of single-cell samples relies on conventional techniques such as pipetting that are labor intensive. In this study, we developed a system combining a 0.

Profiling of N-linked glycans from 100 cells by capillary electrophoresis with large-volume dual preconcentration by isotachophoresis and stacking.

Glycan structure is changed in response with pathogenesis like cancer. Profiling of glycans from limited number of pathogenetic cells in an early-stage tissue is essential for discovering effective drugs. For analyzing tiny biological samples, we developed sensitive, high-resolution, and salt-tolerant method for analyzing trace level of N-linked glycans by coupling capillary electrophoresis (CE), laser-induced fluorescence (LIF) detection, and a new online sample preconcentration (OSP) method named "large-volume dual preconcentration by isotachophoresis and stacking (LDIS)", which is composed of two OSP methods, large-volume sample stacking (LVSS) and transient isotachophoresis (tITP).

A method of packaging molecule/cell-patterns in an open space into a glass microfluidic channel by combining pressure-based low/room temperature bonding and fluorosilane patterning.

We report a fabrication method of a "post-molecule/cell patterned" glass microchip using pressure-based low/room temperature bonding in dry conditions combined with fluorosilane patterning. Multiple proteins/cells were patterned in a single channel using this method. This simple method will provide benefits for using microchips for high throughput analysis in many biological experiments.

Micro/nanoparticle separation via curved nano-gap device with enhanced size resolution.

Micro/nanoparticles are widely found in industry and biological field to play important roles and particle size distribution is an important factor to evaluate these particles. Nano-gap device has advantages in size determination for particles in diverse size and/or shape, but it has difficulty in practical use due to severe requirement on instrumental alignment to reproduce the gap profile and non-quantitative sample injection based on capillary action. To solve these problems, curved nano-gap device (CGD) was fabricated from two flat glass plates via a simple microfabrication process to gain enhanced size resolution, and pressure-driven liquid delivery system was coupled to CGD.

D-Alanine in the islets of Langerhans of rat pancreas.

Relatively high levels of D-alanine (D-Ala), an endogenous D-amino acid, have been found in the endocrine systems of several animals, especially in the anterior pituitary; however, its functional importance remains largely unknown. We observed D-Ala in islets of Langerhans isolated from rat pancreas in significantly higher levels than in the anterior/intermediate pituitary; specifically, 180±60 fmol D-Ala per islet (300±100 nmol/gislet), and 10±2.5 nmol/g of wet tissue in pituitary.

Signals from the brainstem sleep/wake centers regulate behavioral timing via the circadian clock.

Sleep-wake cycling is controlled by the complex interplay between two brain systems, one which controls vigilance state, regulating the transition between sleep and wake, and the other circadian, which communicates time-of-day. Together, they align sleep appropriately with energetic need and the day-night cycle. Neural circuits connect brain stem sites that regulate vigilance state with the suprachiasmatic nucleus (SCN), the master circadian clock, but the function of these connections has been unknown.

D-Aspartate acts as a signaling molecule in nervous and neuroendocrine systems.

D-Aspartate (D-Asp) is an endogenous amino acid in the central nervous and reproductive systems of vertebrates and invertebrates. High concentrations of D-Asp are found in distinct anatomical locations, suggesting that it has specific physiological roles in animals. Many of the characteristics of D-Asp have been documented, including its tissue and cellular distribution, formation and degradation, as well as the responses elicited by D-Asp application.

A novel pyridoxal 5'-phosphate-dependent amino acid racemase in the Aplysia californica central nervous system.

D-aspartate (D-Asp) is found in specific neurons, transported to neuronal terminals and released in a stimulation-dependent manner. Because D-Asp formation is not well understood, determining its function has proved challenging. Significant levels of D-Asp are present in the cerebral ganglion of the F- and C-clusters of the invertebrate Aplysia californica, and D-Asp appears to be involved in cell-cell communication in this system.

Photochemical Smiles rearrangement and Meisenheimer complex formation catalyzed by hydroxide ion via electron hole transfer catalysis.

[reactions: see text] Photochemical para-to-nitro Smiles rearrangement and para-to-nitro Meisenheimer complex formation occurs for nitrophenoxyethylamines with high concentrations of hydroxide ion in aqueous solution. Both photoreactions show first-order dependence on hydroxide ion concentration, but the mechanism involving hydroxide ion does not involve acid-base catalysis. The reactions take place from the triplet excited states of the nitrophenyl ethers.