Local nano-electrode fabrication utilizing nanofluidic and nano-electrochemical control.

Miniaturized systems have attracted much attention with the recent advances in microfluidics and nanofluidics. From the capillary electrophoresis, the development of glass-based microfluidic and nanofluidic technologies has supported advances in microfluidics and nanofluidics. Most microfluidic systems, especially nanofluidic systems, are still simple, such as systems constructed with simple straight nanochannels and bulk-scale electrodes.

Quantitative characterization of liquids flowing in geometrically controlled sub-100 nm nanofluidic channels.

With development of nanotechnologies, applications exploiting nanospaces such as single-molecule analysis and high-efficiency separation have been reported, and understanding properties of fluid flows in 10 nm to 10 nm scale spaces becomes important. Nanofluidics has provided a platform of nanochannels with defined size and geometry, and revealed various unique liquid properties including higher water viscosity with dominant surface effects in 10 nm spaces. However, experimental investigation of fluid flows in 10 nm spaces is still difficult owing to lack of fabrication procedure for 10 nm nanochannels with smooth walls and precisely controlled geometry.

Fabrication of a Gelatin-Based Microdevice for Vascular Cell Culture.

This study presents a novel technique for fabricating microfluidic devices with microbial transglutaminase-gelatin gels instead of polydimethylsiloxane (PDMS), in which flow culture simulates blood flow and a capillary network is incorporated for assays of vascular permeability or angiogenesis. We developed a gelatin-based device with a coverslip as the bottom, which allows the use of high-magnification lenses with short working distances, and we observed the differences in cell dynamics on gelatin, glass, and PDMS surfaces. The tubes of the gelatin microfluidic channel are designed to be difficult to pull out of the inlet hole, making sample introduction easy, and the gelatin channel can be manipulated from the cell introduction to the flow culture steps in a manner comparable to that of a typical PDMS channel.

Stability of enzyme immobilized on the nanofluidic channel surface.

The lifetime of an enzyme is critical to prevent system failure and optimize maintenance schedules in biological and analytical chemistry. The lifetime metrics of an enzyme can be evaluated from enzyme activity in terms of catalytic cycles per enzyme at various storage times. Trypsin, which is a gold-standard enzyme in proteomics, has been known to decrease activity due to self-digestion.

Enzyme-linked immunosorbent assay using thin-layered microfluidics with perfect capture of the target protein.

We developed a process for enzyme-linked immunosorbent assay on a glass microchip the use of a thin-layered microfluidic channel. This channel possesses a high aspect ratio (width/depth ∼200) and has an antibody layer immobilized directly on the channel surface. A depth of several microns and an excessive width and length (mm scale) of the channel provide a large-volume capacity (10 nL) and maximum capture efficiency of the analyte for a high level of detection sensitivity (10 pg mL).

Nanofluidic analytical system integrated with nanochannel open/close valves for enzyme-linked immunosorbent assay.

There have been significant advances in the field of nanofluidics, and novel technologies such as single-cell analysis have been demonstrated. Despite the evident advantages of nanofluidics, fluid control in nanochannels for complicated analyses is extremely difficult because the fluids are currently manipulated by maintaining the balance of driving pressure. To address this issue, the use of valves will be essential.

Kinetics of Enzymatic Reactions at the Solid/Liquid Interface in Nanofluidic Channels.

Nanostructures can realize highly efficient reactions due to their structural advantages. However, the mechanism of accelerating enzyme reactions in a nanospace is still unknown from a kinetic perspective because it is difficult to control a well-defined nanospace, enzyme density, and reaction time. Here, we investigated kinetic parameters of an immobilized enzyme in micro- and nanochannels using nanofabrication, partial enzyme patterning, fluidic control, and a high sensitivity detection system.

Proton diffusion and hydrolysis enzymatic reaction in 100 nm scale biomimetic nanochannels.

Liquids in 10-100 nm spaces are expected to play an important role in biological systems. However, the liquid properties and their influence on biological activity have been obscured due to the difficulty in nanoscale measurements, either or . In this study, an analytical platform for biological systems is established.

Femtoliter-Droplet Mass Spectrometry Interface Utilizing Nanofluidics for Ultrasmall and High-Sensitivity Analysis.

In the fields of biology and medicine, comprehensive protein analysis at the single-cell level utilizing mass spectrometry (MS) with pL sample volumes and zmol to amol sensitivity is required. Our group has developed nanofluidic analytical pretreatment methods that exploit nanochannels for downsizing chemical unit operations to fL-pL volumes. In the field of analytical instruments, mass spectrometers have advanced to achieve ultrahigh sensitivity.

Correction: Integration of sequential analytical processes into sub-100 nm channels: volumetric sampling, chromatographic separation, and label-free molecule detection.

Correction for 'Integration of sequential analytical processes into sub-100 nm channels: volumetric sampling, chromatographic separation, and label-free molecule detection' by Yoshiyuki Tsuyama , , 2021, , 8855-8863, https://doi.org/10.1039/D0NR08385B.

Characterization of pressure-driven water flows in nanofluidic channels by mass flowmetry.

With developments in analytical devices promoted by nanofluidics, estimation of the flow rate in a nanochannel has become important to calculate volumes of samples and reagents in chemical processing. However, measurement of the flow rate in nanospaces remains challenging. In the present study, a mass flowmetry system was developed, and the flow rate of water by pressure-driven flow in a fused-silica nanochannel was successfully measured in picoliters per second.

Accelerated protein digestion and separation with picoliter volume utilizing nanofluidics.

Single cell analyses can provide critical biological insight into cellular heterogeneity. In particular, the proteome, which governs cell functions, is much more difficult to analyze because it is principally impossible to amplify proteins compared to nucleic acids. The most promising approach to single cell proteomics is based on the liquid chromatography mass spectrometry (LC-MS) platform.

Surface Patterning of Closed Nanochannel Using VUV Light and Surface Evaluation by Streaming Current.

In nanofluidics, surface control is a critical technology because nanospaces are surface-governed spaces as a consequence of their extremely high surface-to-volume ratio. Various surface patterning methods have been developed, including patterning on an open substrate and patterning using a liquid modifier in microchannels. However, the surface patterning of a closed nanochannel is difficult.

Interleukin-31 promotes fibrosis and T helper 2 polarization in systemic sclerosis.

Systemic sclerosis (SSc) is a chronic multisystem disorder characterized by fibrosis and autoimmunity. Interleukin (IL)-31 has been implicated in fibrosis and T helper (Th) 2 immune responses, both of which are characteristics of SSc. The exact role of IL-31 in SSc pathogenesis is unclear.

Metal-Free Fabrication of Fused Silica Extended Nanofluidic Channel to Remove Artifacts in Chemical Analysis.

In microfluidics, especially in nanofluidics, nanochannels with functionalized surfaces have recently attracted attention for use as a new tool for the investigation of chemical reaction fields. Molecules handled in the reaction field can reach the single-molecule level due to the small size of the nanochannel. In such surroundings, contamination of the channel surface should be removed at the single-molecule level.

Diffraction-based label-free photothermal detector for separation analyses in a nanocapillary.

Miniaturization of column diameter in liquid chromatography is one of the major trends in separation sciences toward single-cell proteomics and metabolomics. Micro/nanoscale open tubular (OT) capillaries are promising tools for efficient separation analyses of the ultra-small volume of samples. However, highly sensitive and label-free on-column detection is still challenging for such ultra-small capillaries.

Integration of sequential analytical processes into sub-100 nm channels: volumetric sampling, chromatographic separation, and label-free molecule detection.

The progress of nanotechnology has developed nanofluidic devices utilizing nanochannels with a width and/or depth of sub-100 nm (10 nm channels), and several experiments have been implemented in ultra-small spaces comparable to DNAs and proteins. However, current experiments utilizing 10 nm channels focus on a single function or operation; integration of multiple analytical operations into 10 nm channels using nanofluidic circuits and fluidic control has yet to be realized despite the advantage of nanochannels. Herein, we report the establishment of a label-free molecule detection method for 10 nm channels and demonstration of sequential analytical processes using integrated nanofluidic devices.

Isotope Effect in the Liquid Properties of Water Confined in 100 nm Nanofluidic Channels.

Liquids confined in 10-100 nm spaces show different liquid properties from those in the bulk. Proton transfer plays an essential role in liquid properties. The Grotthuss mechanism, in which charge transfer occurs among neighboring water molecules, is considered to be dominant in bulk water.

Advanced Top-Down Fabrication for a Fused Silica Nanofluidic Device.

Nanofluidics have recently attracted significant attention with regard to the development of new functionalities and applications, and producing new functional devices utilizing nanofluidics will require the fabrication of nanochannels. Fused silica nanofluidic devices fabricated by top-down methods are a promising approach to realizing this goal. Our group previously demonstrated the analysis of a living single cell using such a device, incorporating nanochannels having different sizes (10-10 nm) and with branched and confluent structures and surface patterning.

Advances in Label-Free Detections for Nanofluidic Analytical Devices.

Nanofluidics, a discipline of science and engineering of fluids confined to structures at the 1-1000 nm scale, has experienced significant growth over the past decade. Nanofluidics have offered fascinating platforms for chemical and biological analyses by exploiting the unique characteristics of liquids and molecules confined in nanospaces; however, the difficulty to detect molecules in extremely small spaces hampers the practical applications of nanofluidic devices. Laser-induced fluorescence microscopy with single-molecule sensitivity has been so far a major detection method in nanofluidics, but issues arising from labeling and photobleaching limit its application.

Picoliter enzyme reactor on a nanofluidic device exceeding the bulk reaction rate.

Single-cell analyses have recently become important to understand cell heterogeneity, the mechanism of cell function, and diseases. In contrast to single-cell analyses that target nucleic acids, single-cell protein analyses still pose challenges. We have proposed a general concept of integration and extended this concept to the 10-1000 nm scale with femtoliter-picoliter volumes which are smaller than the volume of a single cell exploring ultimate analytical performances (e.

Lipid Bilayer-Modified Nanofluidic Channels of Sizes with Hundreds of Nanometers for Characterization of Confined Water and Molecular/Ion Transport.

Water inside and between cells with dimensions on the order of 10-10 nm such as synaptic clefts and mitochondria is thought to be important to biological functions, such as signal transmissions and energy production. However, the characterization of water in such spaces has been difficult owing to the small size and complexity of cellular environments. To this end, we proposed and fabricated a biomimetic nanospace exploiting nanofluidic channels with defined dimensions of hundreds of nanometers and controlled environments.

Nanochannel chromatography and photothermal optical diffraction: Femtoliter sample separation and label-free zeptomole detection.

Column miniaturization of liquid chromatography is a major trend in separation sciences with the advent of single-cell proteomics and metabolomics. Nanochannel chromatography is one of the promising tools for single-cell analyses because it provides ultra-small sample volume and high separation efficiency. However, non-fluorescent molecular detection in such small channels is still quite difficult due to fL-aL sample volume, which hinders further miniaturization of nanochannels.

Size Sorting of Exosomes by Tuning the Thicknesses of the Electric Double Layers on a Micro-Nanofluidic Device.

Exosomes, a type of extracellular vesicle with a diameter of 30-150 nm, perform key biological functions such as intercellular communication. Recently, size sorting of exosomes has received increasing attention in order to clarify the correlation between their size and components. However, such sorting remains extremely difficult.