Naoya Jinno's research while affiliated with Doshisha University and other places

A new type of tube radial distribution phenomenon was observed in an aqueous micellar solution of non-ionic surfactant that was fed into a microspace. A homogeneous aqueous solution containing 2 wt % Triton X-100 and 2.0 M sodium chloride was fed into a microchannel (40 μm in depth and 200 μm in width) in a microchip at a flow rate of 4.0 μL/min, where the microchip was maintained at a temperature of 34°C. The homogeneous aqueous solution changed to a heterogeneous solution with two phases in the microchannel; the surfactant-rich phase was generated around the middle of the channel, while the aqueous phase containing little surfactant was formed near the wall. The radial distribution of the surfactant was observed through Rhodamine B dissolved in the aqueous micellar solution with a bright-field microscope — CCD camera system. An open-tubular capillary chromatographic system was also tried to develop using the fusedsilica capillary tube (75 μm inner diameter and 120 cm length) as a separation column and the aqueous micellar solution as a carrier.

An open-tubular capillary chromatography system has been developed using a ternary mixed solvent solution, i.e., water-hydrophilic/hydrophobic organic solvent mixture as a carrier solution. The system is called "tube radial distribution chromatography (TRDC)." In this study, we tried to carry out the TRDC on a microchip incorporating microchannels. A model analyte solution of isoluminol isothiocyanate (ILITC) and ILITC-labeled bovine serum albumin (BSA) was injected to the double T-junction part (0.5 mm length, ca. 2 nL) on the microchip. The analyte solution was then delivered in the separation microchannel (40 mu m in depth, 100 mu m in width, and 22 cm in length) with a ternary water-acetonitrile-ethyl acetate mixture carrier solution (3:8:4, volume ratio). The model analytes, the ILITC and the labeled BSA were separated through the microchannel, where the carrier solvents were radially distributed in the separation channel generating inner and outer phases. This phenomenon of the solvents is called "tube radial distribution phenomenon (TRDP)." The outer phase functions as a pseudo-stationary phase under laminar flow conditions in the chromatography, i.e., TRDC. Finally, the ILITC and the labeled BSA were eluted in this order and detected with chemiluminescence reaction.

A capillary chromatography system that consists of an open capillary tube composed of fused silica, polyethylene, and poly(tetrafluoroethylene), and a water–hydrophilic/hydrophobic organic mixture carrier solution has been developed. We call this system the tube radial distribution chromatography (TRDC) system. In this study, variance, theoretical plate number, and height equivalent to a theoretical plate for a solute peak in the chromatogram were expressed using theoretical equations derived from the differential equation for the secondary moment of a solute. The relationship between the thickness and diffusion coefficient in the outer phase in the capillary tube in the TRDC system was calculated from theoretical equations using numerical values for the analytical conditions and experimental data. The outer phase that featured the TRDC system had a larger diffusion coefficient and a larger thickness than those of the stationary phase in standard liquid chromatography. We confirmed the separation performance obtained on the basis of the tube radial distribution of the carrier solvents under laminar flow conditions in the TRDC system by considering the inner and outer phase generation in the capillary tube.

An open-tubular capillary chromatography was developed based on the tube radial distribution of the ternary mixed carrier solvents that generated the inner and outer phases under laminar flow conditions. This is called "tube radial distribution chromatography" (TRDC). In this report, the elution behavior of lambda-DNA (48502 bp) as a biopolymer was examined by the TRDC system. The ternary mixture of water-acetonitrile-ethyl acetate, 15:3:2 or 3:8:4 volume ratio, as a carrier solution was fed into the capillary tube made of polytetrafluoroethylene (PTFE) or fused-silica. The mixture of hydrophobic 1-naphthol and hydrophilic lambda-DNA was subjected to the TRDC system using the water-rich carrier solution. Lambda-DNA and 1-naphthol were distributed between the inner and outer phases due to their hydrophilic and hydrophobic nature, and then eluted in this order, undergoing chromatographic separation. The mixture of hydrophilic 2,6-naphthalenedisulfonic acid and hydrophobic lambda-DNA that was treated with surfactants was also examined with the organic solvent-rich carrier solution. The modified hydrophobic DNA and 2,6-naphthalenedisulfonic acid were distributed and eluted in this order due to their nature.

A micro-flow reaction system was developed in which liquid-liquid interface was created based on the tube radial distribution of ternary mixed carrier solvents. The system was constructed from double capillary tubes having different inner diameters (100 and 250 µm i.d.). The smaller tube was inserted into the larger one through a T-type joint. The reaction of a protein with a fluorescence derivatizing reagent was adopted as a model. A water-acetonitrile mixture (3:1 volume ratio) including bovine serum albumin (hydrophilic) was delivered into the large tube from the inside through the small tube and an acetonitrile-ethyl acetate mixture (7:4 volume ratio) containing fluorescamine (hydrophobic) as a derivatizing reagent was delivered from the outside through the joint. Solutions were mixed through the double capillary tubes to promote ternary mixed carrier solvents (water-acetonitrile-ethyl acetate; 1:2:1 volume ratio). The liquid-liquid interface was created based on the tube radial distribution of ternary solvents in the larger tube. The derivatization reaction was performed in the larger, or reaction, tube in the micro-flow system. The fluorescence intensity of the fluorescamine-derivatized bovine serum albumin obtained by the system, which specifically included the kinetic liquid-liquid interface in the tube, was greater than that obtained through a batch reaction using a homogeneous solution of water-acetonitrile (1:2 volume ratio).

When the ternary mixed solvents of a water-hydrophilic/hydrophobic organic solvent mixture are delivered under microspace under laminar flow conditions, the solvent molecules are radially distributed in the microspace, and generate a major inner phase and a minor outer phase. We call this fluidic phenomenon as the tube radial distribution phenomenon (TRDP). In this paper, phase formation in the TRDP was collectively considered based on experimental data, such as the inner and outer phase formation in a microchannel under laminar flow conditions, the phase diagram for the ternary mixed solvents, the solvent-component ratios required for the TRDP, and the phase transformation in a batch vessel above atmospheric pressure, which were mainly reported in our previous papers. Furthermore, the formation of inner and outer phases in a capillary tube was simulated with the two-component solvents mixture model of water and ethyl acetate. Phase formations in capillary tubes were expressed through computer simulations.

The mixing process of ternary solvents (water-hydrophilic/hydrophobic organic mixture) prepared in microchannels in a microchip was examined by fluorescence observation of the dyes dissolved in the solvents under laminar flow conditions. A microchip incorporating microchannels was used. In it, three narrow channels were combined to form one wide channel. Water-acetonitrile (hydrophilic) mixture containing relatively hydrophilic Eosin Y (green) was fed into the narrow center channel and an acetonitrile-ethyl acetate (hydrophobic) mixture containing hydrophobic perylene (blue) was fed into the two narrow side channels in the microchip. The mixtures in the narrow channels combined in the wide channel to prepare the ternary solvents of water-acetonitrile-ethyl acetate, causing the tube radial distribution of the solvents. We observed the mixing process of the ternary solvents in the wide channel through fluorescence of the green and blue dyes, including an aqueous-organic interface. For example, the green dye that was fed into the center channel was distributed near the inner side walls and the blue dye that was fed into the two side channels was distributed around the center area in the wide channel. Such specific mixing behavior was not observed for two-component solvents in the wide channel, such as water-acetonitrile mixture and water-ethyl acetate mixture.

We examined the elution behavior of isoluminol isothiocyanate (ILITC)-labeled biomolecules (α-amino acids, peptides, and proteins) in an open-tubular capillary chromatography system using an untreated fused-silica capillary tube and a water-acetonitrile-ethyl acetate mixture carrier solution. Such an open-tubular capillary chromatography is called "tube radial distribution chromatography (TRDC)" for convenience. A mixture of ILITC and ILITC-labeled biomolecules was analyzed using TRDC with chemiluminescence detection that provided simple instrument without a light source and complex optical devises. The ILITC and the labeled twenty α-amino acids were separated, in this order or the reverse order, or not separated with an organic solvent-rich and water-rich carrier solution. Their elution behavior was considered to be of hydrophilic or hydrophobic nature of ILITC and the labeled α-amino acids. The ILITC and the labeled protein, alcohol dehydrogenase and bovine serum albumin, were separated in this order with an organic solvent-rich carrier solution, while they were eluted in the reverse order with a water-rich carrier solution, based on the TRDC separation performance. The TRDC system worked with the untreated open-tubular capillary tube not using any specific capillary tubes, such as coated, packed, or monolithic.

Tube radical distribution chromatography (TRDC) uses an untreated open tubular capillary tube and a ternary mixture of solvents (water and hydrophilic/hydrophobic organic solvents) as a carrier solution. A model analyte mixture comprising 1-naphthol, 1-naphthoic acid, 1-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, and 1,3,6-naphthalenetrisulfonic acid was examined by the TRDC and capillary zone electrophoresis (CZE) systems that comprised mainly a capillary tube and a detector. In the TRDC system the elution order of analytes could be changed by altering the component ratios of the solvents, whereas in the CZE system the elution order was changed by altering the electroosmotic flow direction. The experimental data obtained provide clues about the features and utility of TRDC as a new separation method.