Flexible Glass-Based Hybrid Nanofluidic Device to Enable the Active Regulation of Single-Molecule Flows.

Single-molecule studies offer deep insights into the essence of chemistry, biology, and materials science. Despite significant advances in single-molecule experiments, the precise regulation of the flow of single small molecules remains a formidable challenge. Herein, we present a flexible glass-based hybrid nanofluidic device that can precisely block, open, and direct the flow of single small molecules in nanochannels.

A pressure driven electric energy generator exploiting a micro- to nano-scale glass porous filter with ion flow originating from water.

We demonstrated a pressure driven energy harvesting device using water and that features a glass filter with porous channels. We employed powder sintering to fabricate the glass filter (2 cm diameter, 3 mm thickness) by packing a powder of borosilicate glass particles into a carbon mold and then thermally fusing this at 700°C under pressure. In constant flow rate experiment, the optimum average pore radius of the filter for power generation was 12 μm.

Anhydrobiotic chironomid larval motion-based multi-sensing microdevice for the exploration of survivable locations.

African chironomid () larvae can suspend their metabolism by undergoing severe desiccation and then resume this activity by simple rehydration. We present a microdevice using interdigital comb electrodes to detect the larval motion using the natural surface charge of the living larvae in water. The larvae were most active 2 h after soaking them in water at 30°C; they exhibited motions with 2 Hz frequency.

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.

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.

Rapid and easy-to-use ES cell manipulation device with a small groove near culturing wells.

Objective: Production of genetically modified mice including Knock-out (KO) or Knock-in (KI) mice is necessary for organism-level phenotype analysis. Embryonic stem cell (ESC)-based technologies can produce many genetically modified mice with less time without crossing. However, a complicated manual operation is required to increase the number of ESC colonies.

Vacuum microcasting of 2-methacryloyloxyethyl phosphorylcholine polymer for stable cell patterning.

This study demonstrates the rapid fabrication and utility of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer film for cell patterning. The film was obtained on a cell culture surface by microcasting MPC polymer ethanol solution into a degassed polydimethylsiloxane mold with a desired pattern. After removal of the mold, 293AD cells were cultured on the surface of the polymer film with the patterned microstructures.

User-friendly cell patterning methods using a polydimethylsiloxane mold with microchannels.

Techniques for partitioning cell adhesion are useful tools in biological and medical experiments. However, conventional cell patterning methods require special apparatus, special materials or high-level skills. Therefore, we have developed a new cell patterning methodology which can be easily carried out in biological laboratories.

A valve powered by earthworm muscle with both electrical and 100% chemical control.

Development of bio-microactuators combining microdevices and cellular mechanical functions has been an active research field owing to their desirable properties including high mechanical integrity and biocompatibility. Although various types of devices were reported, the use of as-is natural muscle tissue should be more effective. An earthworm muscle-driven valve has been created.

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.

Analysis of Long-term Morphological Changes of Micro-patterned Molecules and Cells on PDMS and Glass Surfaces.

We demonstrated that our previously developed gas-phase fluoroalkylsilane patterning method was applicable to polydimethylsiloxane (PDMS) and we compared the stability of patterned proteins and cultured cells between PDMS and glass surfaces. The shapes of the protein patterns were stable on both glass and PDMS surfaces for more than 1 week. The cell patterns were stable on glass surfaces for 1 week, while those on PDMS collapsed within a few days.

An electric generator using living Torpedo electric organs controlled by fluid pressure-based alternative nervous systems.

Direct electric power generation using biological functions have become a research focus due to their low cost and cleanliness. Unlike major approaches using glucose fuels or microbial fuel cells (MFCs), we present a generation method with intrinsically high energy conversion efficiency and generation with arbitrary timing using living electric organs of Torpedo (electric rays) which are serially integrated electrocytes converting ATP into electric energy. We developed alternative nervous systems using fluid pressure to stimulate electrocytes by a neurotransmitter, acetylcholine (Ach), and demonstrated electric generation.

A single-step enzyme immunoassay capillary sensor composed of functional multilayer coatings for the diagnosis of marker proteins.

A single-step, easy-to-use enzyme immunoassay capillary sensor, composed of functional multilayer coatings, was developed in this study. The coatings were composed of substrate-immobilized hydrophobic coating, hydrogel coating, and soluble coating containing an enzyme-labeled antibody. The response mechanism involved a spontaneous immunoreaction triggered by capillary action-mediated introduction of a sample antigen solution and subsequent separation of unreacted enzyme-labeled antibodies and antigen-enzyme-labeled antibody complexes by the molecular sieving effect of the hydrogel.

Advancements in capillary-assembled microchip (CAs-CHIP) development for multiple analyte sensing and microchip electrophoresis.

This review describes advancements toward the development of a capillary-assembled microchip (CAs-CHIP) for simultaneous multiple analyte sensing and microchip capillary electrophoresis. Development of such an advanced system relies on several factors such as improving the fluid handling technique, creating new biosensing mechanisms, and integrating different functional capillaries into a single CAs-CHIP system. Furthermore, we provide an overview of various functional capillaries that have been established for valving and biosensing applications such as ions, metabolites, proteins, and enzyme activities.

Design of a single-step immunoassay principle based on the combination of an enzyme-labeled antibody release coating and a hydrogel copolymerized with a fluorescent enzyme substrate in a microfluidic capillary device.

A combination of an enzyme-labeled antibody release coating and a novel fluorescent enzyme substrate-copolymerized hydrogel in a microchannel for a single-step, no-wash microfluidic immunoassay is demonstrated. This hydrogel discriminates the free enzyme-conjugated antibody from an antigen-enzyme-conjugated antibody immunocomplex based on the difference in molecular size. A selective and sensitive immunoassay, with 10-1000 ng mL(-1) linear range, is reported.

Capillary-based enzyme-linked immunosorbent assay for highly sensitive detection of thrombin-cleaved osteopontin in plasma.

In this study, a highly sensitive capillary-based enzyme-linked immunosorbent assay (ELISA) has been developed for the analysis of picomolar levels of thrombin-cleaved osteopontin (trOPN), a potential biomarker for ischemic stroke, in human plasma. Using a square capillary coated with 8.5 μg/ml anti-human trOPN capture antibody for ELISA, the linear range obtained was 2 to 16 pM trOPN antigen.

Novel fluorescent probe for highly sensitive bioassay using sequential enzyme-linked immunosorbent assay-capillary isoelectric focusing (ELISA-cIEF).

This paper presents a novel rhodamine diphosphate molecule that allows highly sensitive detection of proteins by employing sequential enzyme-linked immunosorbent assay and capillary isoelectric focusing (ELISA-cIEF). Seven-fold improvement in the immunoassay sensitivity and a 1-2 order of magnitude lower detection limit has been demonstrated by taking advantage of the combination of the enzyme-based signal amplification of ELISA and the concentration of enzyme reaction products by cIEF.

Single-step sandwich immunoreaction in a square glass capillary immobilizing capture and enzyme-linked antibodies for simplified enzyme-linked immunosorbent assay.

To simplify the complicated operation steps and to minimize sample and reagent amounts for enzyme-linked immunosorbent assays (ELISA), we developed a square glass capillary immunosensor containing both covalently immobilized capture antibodies and physically adsorbed enzyme-linked antibodies. The immobilization of capture antibodies (anti-human IgG) was carried out by the treatment of 3-aminopropyltriethoxy silane, glutaraldehyde, and protein-A, followed by affinity capture of the antibody. In contrast, the enzyme-linked antibodies (alkaline phosphatase (ALP)-linked anti-human IgG) were physically adsorbed on the four corners of the capillary with the aid of polyethylene glycol (PEG) acting as a scaffold.

Integration of valving and sensing on a capillary-assembled microchip.

A simple integration of both flow control valves and a reaction-based sensing function on a single microchip was performed by using capillary-assembled microchip (CAs-CHIP: Hisamoto, H.; Nakashima, Y.; Kitamura, C.

Capillary-assembled microchip for universal integration of various chemical functions onto a single microfluidic device.

A novel concept for assembling various chemical functions onto a single microfluidic device is proposed. The concept, called a capillary-assembled microchip, involves embedding chemically functionalized capillaries into a lattice microchannel network fabricated on poly(dimethylsiloxane) (PDMS). The network has the same channel dimensions as the outer dimensions of the capillaries.