Biomedical subjects

Yoshiaki Kashimura

Publications and source records attributed to Yoshiaki Kashimura.

6 recordsLinked to original sources

PubMed2007

Supported lipid bilayer self-spreading on a nanostructured silicon surface.

We report on the self-spreading behavior of a supported lipid bilayer (SLB) on a silicon surface with various 100 nm nanostructures. SLBs have been successfully grown from a small spot of a lipid molecule source both on a flat surface and uneven surfaces with 100 nm up-and-down nanostructures. After an hour, the self-spreading SLB forms a large circle or an ellipse depending on the nanostructure pattern. The results are explained by a model that shows that a single-layer SLB grows along the nanostructured surfaces. The model is further supported by a quantitative analyses of our data. We also discuss the stability of the SLB on nanostructured surfaces in terms of the balance between its bending and adhesion energies.

Animals↗

PubMed2006

A new morphology of copper 7,7,8,8-tetracyano-p-quinodimethane.

Morphology control is a long-standing problem that needs to be solved for making the switching mechanism of copper 7,7,8,8-tetracyano-p-quinodimethane (CuTCNQ) understood all the time, but up till now how many morphologies CuTCNQ possesses and which morphology should be responsible for the on/off switching phenomenon are still unclear. A new morphology of CuTCNQ, namely the tubular structure, has been obtained and characterized in our experiment, whose formation mechanism has also been investigated. Through characterizing, we can conclude that the tubular structure belongs to the phase I, which can be further confirmed by the electrical measurements. From the I-V plots, the carrier mobility of the tubular structure is estimated to be approximately 0.1 cm2 V-1 s-1, which suggests the potential application of CuTCNQ in devices.

Journal Article↗

PubMed2006

Microchannel device using self-spreading lipid bilayer as molecule carrier.

We propose a microchannel device that employs a surface-supported self-spreading lipid bilayer membrane as a molecule carrying medium. The device has a micropattern structure fabricated on a SiO2 surface by photolithography, into which a self-spreading lipid bilayer membrane is introduced as the carrier medium. This system corresponds to a microchannel with a single lipid bilayer membrane height of approximately 5 nm, compared with conventional micro-fluidic channels that have a section height and width of at least several microm. The device is beneficial for detecting intermolecular interactions when molecules carried by the self-spreading lipid bilayer collide with each other in the microchannel. The validity of the device was confirmed by observing the fluorescence resonance energy transfer (FRET) between two dye molecules, coumarin and fluorescein.

Coumarins↗

PubMed2006

Electron transport in self-assembled polymer molecular junctions.

A molecular junction of a poly(p-phenyleneethynylene)s derivative with thioacetate end groups (TA-PPE) was fabricated by self-assembling. Nanogap electrodes made by electroplating technique was used to couple thiol end groups of TA-PPE molecules. Room temperature current-voltage characteristics of the molecular junction exhibited highly periodic, repeatable, and identical stepwise features. First-principles calculations suggest that one possibility for the equidistant step is due to the opening of different conducting channels that corresponds to the unoccupied molecular orbitals of the polymer in the junction. It is interesting to see that an 18 nm long polymer is of quantized electronic structures and behaves like a quantum transport device.

Journal Article↗

PubMed2005

A self-assembled nano optical switch and transistor based on a rigid conjugated polymer, thioacetyl-end-functionalized poly(para-phenylene ethynylene).

A nanometer-scale optical switch and transistor were fabricated with thioacetyl-end-functionalized poly(para-phenylene ethynylene)s and Au nanogap electrodes by self-assembly. With photoirradiation, the switch can be switched on/off quickly with a switching ratio as high as 1000. Moreover, the device works well as a p-type transistor. With an increase in gate bias, strong conductance oscillation was observed in this self-assembled transistor (under low temperature 147 K), which is very likely due to single-electron charging oscillations arising from electron tunneling through the nanometer-scale transistor.

Journal Article↗

PubMed2005

Selective chemisorption of end-functionalized conjugated polymer on macro- and nanoscale surfaces.

Linear and conjugated poly(p-phenylene ethynylene)s (PPEs) with three different types of functionalized end groups (thiolacetate, isocyanide, and carboxylic acid groups) were synthesized, and their selective chemisorption behavior on various substrate surfaces were investigated using UV/vis transmission absorption spectroscopy. The UV/vis spectra of the PPEs were clearly dependent on the chemical affinity between the PPE end group and the solid surfaces. Furthermore, regarding the chemisorption of thiolacetate modified polymer on a nanoscopic gold particle surface, we visualized novel polymer-colloid nanoarchitectures such as a barbell-type nanohybrid and interconnected polymer nanowire structures that are successively linked through gold nanoparticles.

Letter↗