Hideyuki Mitomo

Overexpression of the ATP-binding cassette transporter ABCG2 reportedly causes multidrug resistance, whereas altered drug-resistance profiles and substrate specificity are implicated for certain variant forms of ABCG2. At least three variant forms of ABCG2 have been hitherto documented on the basis of their amino acid moieties (i.e., arginine, glycine and threonine) at position 482. In the present study we have generated those ABCG2 variants by site-directed mutagenesis and expressed them in HEK

The development of a strategy for the assembly of nanoscale building blocks, in particular, anisotropic nanoparticles, into desired structures is important for the construction of functional materials and devices. However, control over the orientation of rod-shaped nanoparticles on a substrate for integration into solid-state devices remains challenging. Here, we report a strategy for the fabrication of finely aligned gold nanorod (GNR) arrays using polymer (DNA) brushes as a nanoscale template.

Nearest-neighbor recognition measurements have been made for an exchangeable phospholipid (A) interacting with an exchangeable form of cholesterol (B) in host membranes derived from 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine and varying concentrations of cholesterol, 7beta-hydroxycholesterol (7beta-OH), and 25-hydroxycholesterol (25-OH). Whereas partial replacement of cholesterol with 7beta-OH strengthens the association between A and B, a similar substitution with 25-OH weakens this associati

Active plasmonic tuning is an attractive but challenging research subject, leading to various promising applications. As one of the approaches, nanostructures are placed in or on soft matter, such as elastomers and gels, and their gap distances are tuned by the mechanical extension or volume change of the supporting matrices. As hydrogels possess various types of stimuli-responsiveness with large volume change and biocompatibility, they are good candidates as supporting materials for active nano

Abstract This review introduces recent advances in the fabrication of metal nanostructures via self-assembly with a particular focus on our studies. As nanostructures, in particular metal nanostructures, show unique properties which are not observed in bulk materials, the development of nanofabrication techniques has attracted much attention in the research fields of nanoscience and nanotechnologies. From the viewpoint of biomimetics, it is imagined that sophisticated structures with spatio-temp

The emerging concept of tunable plasmonic chirality is mostly observed as a reconfigurable behavior or a feature of complex chiral plasmonic assemblies. For discrete colloidal particles, it is challenging to achieve reversible tunability or a transient response with regard to chiroptical activities, particularly in the visible or near-infrared region. Herein, we demonstrate a stimulus-responsive system based on chiral molecule–achiral plasmonic nanoparticles coated with polyaniline (PANI) as a v

Nanoparticles exhibit a number of unique properties such as localized surface plasmon resonance (LSPR). As this LSPR is sensitive to geometrical or spatial conditions, the arrangement of nanoparticles, in particular the active arrangement of plasmonic structures, is an important issue. In this study, gold nanorod (GNR) arrays were prepared by GNR attachment on anionic polymer (DNA) brushes <i>via</i> electrostatic interactions and their stimuli-responsive changes in orientation were investigated

Abstract Cube-structured silver nanoparticles (AgNCs) were synthesized and modified with oligo(ethylene glycol) (OEG)-attached alkane-thiol ligands. They showed thermo-responsive color changes dispersed in water and also good dispersibility in CHCl3. They formed well-packed assembled structures at the air-water interface. AgNC assembled films also showed a strong plasmonic property and thermo-responsiveness.

Abstract Inorganic nanoparticles are an attractive material that shows unique properties that differ from their bulk counterparts. Assembly of nanoparticles with soft materials is an effective approach to leverage their unusual properties for the fabrication of functional devices. Among the various soft materials, polymer brushes are expected to offer exciting opportunities due to their unique conformational properties. Here, we review research progress in the assembly and active control of gold

In this study, we demonstrate that the plasmonic properties of gold nanorods (GNRs) electrostatically adsorbed on a DNA brush substrate are reversibly controlled by changes in NaCl concentration. This plasmonic change results from GNR assembly/disassembly in a DNA brush layer. In addition, we show that this active plasmonic system exhibits intense and switchable chiroptical properties.

Assemblies of cationic gold nanorods (AuNRs) via electrostatic interactions with double-stranded (ds) DNA were investigated in solution and after evaporation as a cast-film. Interestingly, moderately positively charged AuNRs assembled with dsDNA provided a monolayer sheet with an ordered alignment resembling a two-dimensional (2D) smectic structure during solvent evaporation. Assemblies of cationic gold nanorods (AuNRs) via electrostatic interactions with double-stranded (ds) DNA were investigat

Anisotropic gold nanodiscs (AuNDs) possess unique properties, such as large flat surfaces and dipolar plasmon modes, which are ideal constituents for the fabrication of plasmonic assemblies for novel and emergent functions. In this report, we present the thermo-responsive assembly and thermo-dynamic behavior of AuNDs functionalized with methyl-hexa(ethylene glycol) undecane-thiol as a thermo-responsive ligand. Upon heating, the temperature stimulus caused a blue shift of the plasmon peak to form

The self-assembly of gold nanoparticles (GNPs) into a defined structure, particularly hollow capsule structures, provides great potential for applications in materials science and medicine. However, the complexity of the parameters for the preparation of those structures through self-assembly has limited access to critical mechanistic questions. With this in mind, we have studied GNP vesicle (GNV) formation through self-assembly by the surface modification of GNPs with low-molecular-weight ligan

Biomolecular systems actively control their local environment on a sub-nm scale <i>via</i> changes in molecular configuration from their flexible structures and derive emergent functions. Although this functional emergence based on local environmental control is attracting a great deal of attention in chemistry, it remains challenging to realize this artificially. Herein, we report the tuning of the thermo-responsive properties of oligo(ethylene glycol) (OEG) derivatives attached on gold nanopar

Abstract Gold nanorods (AuNRs) have unique optical properties such as transverse and longitudinal localized surface plasmon resonance (T‐ and L‐LSPR). As the L‐LSPR absorption depends on the angle of the AuNRs to incident light and polarization, orientational control of AuNRs is a crucial issue. In spite of various techniques to control AuNR orientation, dynamic orientation tuning on a solid substrate remains challenging. Herein, dynamic changes are demonstrated in AuNR orientation in the anioni