Construction of a fiber-optically connected MEG hyperscanning system for recording brain activity during real-time communication.

Communication is one of the most important abilities in human society, which makes clarification of brain functions that underlie communication of great importance to cognitive neuroscience. To investigate the rapidly changing cortical-level brain activity underlying communication, a hyperscanning system with both high temporal and spatial resolution is extremely desirable. The modality of magnetoencephalography (MEG) would be ideal, but MEG hyperscanning systems suitable for communication studies remain rare.

Prism-based spectral imaging of four species of single-molecule fluorophores by using one excitation laser.

A prism-based imaging system for simultaneously detecting four species of single-molecule (SM) fluorophores was developed. As for the detection method, four spectrally distinct species of BigDye fluorophores were bound to 50-nm-diameter gold nanoparticles (AuNPs) to form AuNP/BigDye complexes. Four species of complexes were randomly immobilized on different fused-silica slides.

Dual-view imaging system using a wide-range dichroic mirror for simultaneous four-color single-molecule detection.

A dual-view imaging system for simultaneous four-color single-molecule (SM) detection was developed. As for the detection procedure, four species of SM fluorophores, namely, Alexa 488, 555, 647, and 680, are immobilized on different slides and excited by evanescent-wave illumination. Fluorescence emitted from an SM fluorophore is split by a wide-range dichroic mirror (WR DM) in a dual-view optics and imaged as two SM fluorescence spots (SM spots) on an electron-multiplying charge-coupled device (EM-CCD) at 100 Hz.

Prism-based spectral imaging of single-molecule fluorescence from gold-nanoparticle/fluorophore complex.

A wavelength-calibration method for prism-based spectral imaging of single-molecule (SM) fluorescence was developed. With this method, a wavelength reference is provided by photoluminescence from 50-nm-diameter gold nanoparticles (AuNPs) binding with fluorophores. The AuNPs each bound with a SM fluorophore, either Alexa488 or Cy3, to form AuNP/fluorophore complexes in tris-HCl buffer.

Simultaneous four-color imaging of single molecule fluorophores using dichroic mirrors and four charge-coupled devices.

We developed a total-internal-reflection (TIR) fluorescence microscopy using three dichroic mirrors and four charge-coupled devices (CCDs) to detect simultaneously four colors of single-molecule (SM) fluorophores. Four spectrally distinct species of fluorophores (Alexa 488, Cy3, Cy5, or Cy5.5) were each immobilized on a different fused silica slide.

Improvement of biomolecule quantification precision and use of a single-element aspheric objective lens in fluorescence correlation spectroscopy.

We found a way to increase the precision with which biomolecules present at concentrations below 10(-10) M can be quantified by fluorescence correlation spectroscopy (FCS). The effectiveness of the way was demonstrated experimentally by using a single-element aspheric objective lens, which was newly developed to reduce the cost of FCS instruments. In the first part of this paper, the relative standard deviation (RSD) of FCS-based concentration measurements is estimated theoretically by an analytical approximation assuming the detection volume profiles in FCS setups to be Gaussian and by molecular simulations in which more realistic profiles are calculated from physical parameters of the measurement setups.

Ultra-slim laminated capillary array for high-speed DNA separation.

We developed a new kind of capillary array for electrophoresis by using the numerical-control (NC) wiring technique conventionally used to produce printed-circuit boards. Laminating two polyimide sheets after laying cylindrical capillaries between them according to designed geometries, we fabricated a 16-lane laminated capillary array (LCA) 9.9 cm long, 7.

High-speed DNA sequencing by tube-based capillary electrophoresis.

We assessed the feasibility of high-speed DNA sequencing by tube-based capillary electrophoresis (TCE) with electrokinetic sample injections. We developed a water-circulated TCE system to control the capillary temperature precisely. Using this system and a ready-made sieving matrix at 50 degrees C, single-stranded DNA size marker fragments were separated at various pairs of the electric field strength, E, of 128-480 V/cm and the capillary effective length, L, of 100-360 mm.

High resolution for single-strand conformation polymorphism analysis by capillary electrophoresis.

Since the successful completion of the Human Genome Project, increasing concern is being directed toward the polymorphic aspect of the genome and its clinical relevance. A form of single-strand DNA-conformation polymorphism analysis (SSCP) employing nondenaturing slab-gel electrophoresis (SGE) is applicable to the genetic diagnosis of bladder cancer from urine samples. To bring this technique into routine clinical practice, the use of capillary electrophoresis (CE) is naturally favorable in terms of speed and automation.

Fluorescence correlation spectroscopy excited with a stationary interference pattern for capillary electrophoresis.

Using a combination of capillary electrophoresis (CE) and patterned fluorescence correlation spectroscopy (patterned FCS), we have developed a new technique for performing electrophoretic analysis independently of the initial length of injected analyte plugs. In t histechnique, which is abbreviated as CE/patterned FCS, fluorescent analyte molecules dispersed continuously in a capillary migrate through a stationary interference pattern created by two intersecting excitation laser beams, and their fluorescence emission is monitored. We prove theoretically that the power spectrum of fluctuations in the fluorescence intensity gives a virtual electropherogram.