Kyosuke Kotani

Nanomanipulation of single virus using Dielectrophoretic concentration on a microfluidic chip

A major problem for analysis of bio-nanoparticles such as the influenza viruses (size is about 100 nm) is that sample concentration is low. We developed manipulation of the single virus using optical tweezers supported by dielectrophoretic concentration of the viruses in a microfluidic chip. The microfluidic chip made of poly (dimethyl siloxane) (PDMS) is useful to achieve stable manipulation of the virus. The chip has the independent sample chamber and analysis chamber to make the quantitative analysis of the functions of the virus before and after infection to the target cell. Dielectrophoretic (DEP) force worked inside the sample chamber concentrates the virus. DEP force was also worked for avoiding virus adhesion to the glass substrate. Concentrated virus was flown to the sample selection part and was trapped by optical tweezers. Trapped virus was transported to the analysis chamber and contact to the target cell for infection. In this paper, we described the DEP virus concentration for single virus infection to a specific cell. We succeeded in the DEP concentration of the influenza virus, transport of the single virus transport, and contact to the specific H292 cell.

Nanomanipulation of single influenza virus using optical tweezers and dielectrophoretic force on a microfluidic chip

A major problem for analysis of bio-nanoparticles such as the influenza viruses (size is about 100 nm) is that sample concentration is low. We developed manipulation of the single virus using optical tweezers supported by dielectrophoretic concentration of the viruses in a microfluidic chip. The microfluidic chip made of poly (dimethyl siloxane) (PDMS) is useful to achieve stable manipulation of the virus. The chip has the independent sample chamber and analysis chamber to make the quantitative analysis of the functions of the virus before and after infection to the target cell. Dielectrophoretic (DEP) force worked inside the sample chamber concentrates the virus. DEP force was also worked for avoiding virus adhesion to the glass substrate. Concentrated virus was flown to the sample selection part and was trapped by optical tweezers. Trapped virus was transported to the analysis chamber and contact to the target cell for infection. In this paper, we described the DEP virus concentration for single virus infection to a specific cell. We succeeded in the DEP concentration of the influenza virus, transport of the single virus transport, and contact to the specific H292 cell.

Assembling technique of three dimensional microstructures using clip mechanism of microspring

In this paper, a microassembling technique of microstructures using a silicon clip mechanism is developed for a time-of-flight scanning force microscope (TOF-SFM) probe. Microsprings formed by deep reactive ion etching were used as a clip micromechnism. Microelements are manipulated by a manipulator, and microgap between the microspring and opposite wall is expanded by pulling the microspring using a microneedle. Then the microelement is inserted into the micromechnism, and clipped by releasing the microspring. After assembling, all microelements are fixed with conductive glue. This technique is advantageous to fabricate complex three-dimensional microstructures. We demonstrate the assembling of a microelectrode and microcantilever for TOF-SFM probe.

Injection and laser manipulation of nanotool using photo responsive chemical for intracellular measurement

We developed selective cell injection of nanotool using photo responsive chemical for intracellular measurement. The nanotool was included in the fusogenic liposome. Membrane fusion of the liposome to the cell membrane was used for invasive cell injection of the nanotool. The liposome fuses to the cell in weak acidic condition. Local pH control inside the liposome was developed by using photo responsive chemical included in the nanotool. The nanotool was modified by fluorescent dye for environment measurement. The nanotool was also modified by photo responsive chemical Leuco crystal violet (LCV). LCV emits the proton by UV illumination. The emitted proton decreases pH value inside the liposome. This pH control is reversible by UV/VIS illumination. The nanotool included the liposome was manipulated by optical tweezers. After contact of the liposome to the cell membrane, the liposome was adhered to the cell membrane by UV-ray. The nanotool was injected into the cell autonomously. Injected nanotool was manipulated by optical tweezers. Intracellular temperature was also detected by measuring the fluorescence intensity of the nanotool. We demonstrated photo-induced cell injection of the nanotool and manipulation of the nanotool inside the cell.

Size-dependent microparticle filtration using magnetically driven microtool for producing gel-microtool

In this study, we successfully produced a functional microtool made of gel microbeads using size-dependent microparticle classification. Gel microbeads are made by salting-out hydrophilic photo-crosslinkable resin ENT-3400. These gel microbeads were separated according to their size using microfilters made of polydimethylsiloxane (PDMS). The first filter is a row of fluidic microchannels that block microbeads with a size greater than the channels width. Another filtration method has been examined using a magnetically driven microtool (MMT) to separate the beads using the centrifugal force created by this MMT actuated with a DC motor. Separated gel microbeads were recovered after filtration and used to fabricate functional microtools, for example, a tether-shaped gel tool, by contact with other gel microbeads under UV illumination. The produced gel tool is manipulated using optical tweezers in a microchip. We successfully achieved size-dependent separation of gel microbeads and production of a tether-shaped gel tool.

Production of Functional Microtool Using Size-Classified Gel-Microbeads

In this study, we succeeded in producing functional microtool made of gel-microbead using size-dependent microparticle classification. Gel-microbead, which is used as the material for the microtool, is made by salting-out of hydrophilic photo-crosslinkable resin, ENT-3400. These gel-microbeads were separated according to their size by microfilters made of polydimethylsiloxane (PDMS). A first on is a row of fluidic micro-channels which block microbeads with a size over the width of the channel. Another filtering method has been experimented, using Magnetically driven MicroTool (MMT) to separate the beads using the centrifugal force created by this MMT actuated with a DC motor. Separated gel-microbeads were recovered after filtering step and then used to fabricate functional microtools, for example tether-shaped gel-tool, by contact to other gel-microbeads under UV illumination. Produced gel-tool is manipulated by optical tweezers in a microchip. We succeeded in getting size-dependent separation of the gel-microbeads and production of the tether-shaped gel-tool.