Miniaturization of Slab Gel Electrophoresis Using Thermal Lens Microscope and its Application to Genetic Diagnostics

Slab gel electrophoresis is the most widely used separation method for DNA fragments, proteins and carbohydrates, and miniaturization of this process is expected to provide fast, inexpensive and convenient analyses. However, two problems concerning the miniaturization of gel electrophoresis have to be solved:the separation performance and spatial resolution of the detector. We demonstrated that the separation performance was improved by using a discontinuous gel in which a concentrating gel was used to stack the sample to a sharp band, and using thermal lens microscope (TLM), which is highly sensitive and has a spatial resolution of micron level even in light scattering matrices as a gel, such sharpened separated bands were successfully detected. In this paper, we developed a miniaturized slab gel electrophoresis apparatus, demonstrated high speed separation of DNA fragments, and applied it to genetic diagnosis of coronary heart disease.     

Monitoring of Dynamic Behavior of Phospholipids at Liquid/Liquid Interfaces by a Time-Resolved Quasi-Elastic Laser-Scattering Method

Phospholipids, which consist of a zwitterionic head group connected to a pair of long hydrocarbon chain, constitute the major component of most cell membranes. A monolayer composed of phospholipids at the interface between two immiscible liquids is a useful model system for studying biological and artificial membranes.     

Behavior of Tetraalkylammonium Bromide in Phase Transfer Catalytic Reaction at a Liquid/Liquid Interface as Studied by a Quasi-Elastic Laser Scattering Method

The liquid/liquid interface plays important roles in various processes such as phase transfer catalyst,solvent extraction and ion-selective electrode.     

Transient reflecting gratings for the investigation of photothermal and photoacoustic phenomena localized near surfaces and interfaces

Transient reflecting grating methods have good potential in the investigation of ultrafast photothermal phenomena at opaque subsurfaces. Various applications of ultrasonic and thermal spectroscopies, electrochemical interface monitoring, and imaging are surveyed. Some examples are presented for quantitative determinations of elastic and thermal properties in inhomogeneous materials with tens-of-nanometers' structures.     

Computer-assisted library search system for identification of unknown mass spectra

The library search system described identifies a single component or two components in the unknown pure or mixture mass spectra by comparing them with a large data base of reference spectra. A preliminary search is based on the spectral interpretation and the main search is based on the probability of peak appearance. The performance of this system was tested on 254 pure spectra and 88 mixture spectra. The percentages of successful search by using the NIH/EPA/MSDC data base were 75% for the pure spectra, and 63% for both the first and second components in mixture spectra. The percentages of successful search improved to 94% for the first components of the mixture spectra and 77% for both first and second components of the mixture spectra, when conditions for measurement of reference spectra were the same as those for the unknown spectra.     

Pyrromethene dye sensitized photopolymer—photochemical behavior in polymer matrix and application to photoresist for printed circuit board

The photochemical behavior of the visible light initiating system that consists of a sensitizing dye, 2,6‐diethyl‐8‐phenyl‐1,3,5,7‐tetramethylpyrromethene BF₂ complex (EPP), and a photoacid generator, N‐trifluoromethylsulfonyloxy‐1,8‐naphthalimide (NIOTf), was studied mainly by means of absorption and fluorescence spectrometry not in solution but in a polymer matrix which is a closer medium to the one currently employed in the field of photoresists. Excited singlet electron transfer from EPP to NIOTf was considered as the main reaction pathway in this system. The EPP/NIOTf system was applied to a photoresist for printed circuit board with an appropriate binder polymer which contains an acetal protection group. A pattern profile of the photoresist was exceedingly affected by the amount of photogenerated acids, their diffusion, and amine in the atmosphere. Finally, by controlling exposure energy and the post‐exposure bake (PEB) process, a photoresist with a high resolution (8 µm line and space) was obtained under argon ion laser irradiation. Copyright © 2006 John Wiley & Sons, Ltd.     

Vis‐sensitive photopolymer containing vinyl ether compound and pyrromethene dye

A visible light(vis)‐sensitive photoresist based on the concept of chemical amplification was developed utilizing poly(p‐hydroxystyrene) (PHS), 2,2‐bis[4‐(2‐(vinyloxy)‐ethoxy)phenyl]propane (BPA‐DEVE) as a crosslinking agent, N‐trifluoromethylsulfonyloxy‐1,8‐naphthalimide (NIT) as a photoacid generator (PAG) and pyrromethene dyes such as 1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRH) and 2,8‐diethyl‐1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRE) and 3,3′‐carbonylbis(7,7′‐diethylaminocoumarin) (KCD). On irradiation with an argon ion laser, the photopolymer comprising PRH and PRE exhibited a high sensitivity of 65 and 46 mJ cm^?2, respectively. It is suggested that the sensitization mechanism of the pyrromethene dye/PAG system involves singlet electron transfer. The sensitivity of the photoresist increased with the decreasing molecular weight of PHS because of the high dissolution rate. Copyright © 2002 John Wiley & Sons, Ltd.     

Holographic recording using visible-light sensitive polymers based on cationic polycondensation

Negative-working photopolymers based on a cationic polycondensation mechanism were developed. The photopolymers are highly sensitive to 488 nm argon ion laser light, because they use a chemically amplified reaction and are not sensitive to ambient oxygen. These photopolymers are composed of a poly(p-hydroxystyrene) matrix, a hexamethoxy methylmelamine crosslinker and a 2,4,6-tris(trichloromethyl)-1,3,5-triazine–coumarin dye combination as a photo-initiator. They exhibit 0.6 mJ/cm² (D^0.7_g) sensitivity to 488 nm light, as well as a high resolution of 0.5 μm. Due to their high sensitivity and high resolution, a relief-type hologram, larger than 50 × 50 cm, can be recorded in a short exposure time using them.     

Acid generation and deprotecting reaction by diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate in a novolak positive photoresist based on chemical amplification

In a positive photoresist composed of diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate as a novel photoacid generator, bisphenol A protected with tertbutoxycarbonyl group as a dissolution inhibitor, and a novolak resist matrix, the efficiency of photo-acid generation and deprotective reaction were investigated by means of UV-visible and IR spectroscopies. The quantitative measurement of photogenerated acid by using the acid-sensitive dye exhibited 0.18 as the quantum yield of acid generation in novolak resin film. The lithographic evaluation of this system as a chemically amplified resist was studied. The catalytic chain length for the acid-catalyzed deprotection step was determined as about 100 when 10 min post-exposure bake (PEB) at 80°C was given. The sensitivity and the resolution as a positive resist are 180 mJ/cm² and higher than 1 μm, respectively under the PEB conditions mentioned above.     

Local environment and property of water inside the hollow cylinder of a lipid nanotube

We investigated the local environment of water confined inside the hollow cylinder of lipid nanotubes (LNTs) by time-resolved fluorescent measurements and attenuated-total-reflectance infrared (ATR-IR) spectroscopy. The LNT was obtained by self-assembly of cardanyl glucosides in water at room temperature and had an open-ended cylindrical nanospace with a diameter of 10-15 nm, a length of 10-100 microm, and hydrophilic inner and outer surfaces. We introduced a fluorescent probe of 8-anilinonaphthalene-1-sulfonate into the confined water and observed an extremely slow dynamic Stokes shift with a correlation time of 1.26 ns, which was 2-3 orders of magnitude longer than that of bulk-phase water. From the peak shift of the fluorescent spectrum, the local solvent polarity (ET(30)) of the confined water was estimated as 50 kcal/mol, which is 20% lower than that in bulk water. ATR-IR measurements showed that the hydrogen-bond network of water inside the LNT was more developed than that in bulk water at room temperature, which is in contrast to the water in other self-assembled confined geometries, such as Aerosol-OT (AOT) reversed micelles.