서대하 교수

We report the shape and size control of polyhedral gold nanocrystals by a modified polyol process. The rapid reduction of gold precursors in refluxing 1,5-pentanediol has successfully provided a series of gold nanocrystals in the shape of octahedra, truncated octahedra, cuboctahedra, cubes, and higher polygons by incremental changes of silver nitrate concentration. All nanocrystals were obtained quantitatively and were uniform in shape and size in the range of approximately 100 nm. Smaller octah

Polyhedral gold nanocrystals with decahedral, icosahedral, and truncated tetrahedral shapes are synthesized by a simple one-pot polyol process in the prescence of poly(vinyl pyrrolidone) (PVP). High PVP concentration up to 360 equiv of the gold precursor, HAuCl 4, effectively stabilizes decahedral seeds to yield uniform decahedra with various edge sizes. Decreased PVP concentration subsequently leads to selective formation of icosahedra and truncated tetrahedra. This results from a combination b

The Ag−Au−Ag heterometallic nanorods were synthesized epitaxially though directed anisotropic overgrowth from multiply twinned gold decahedrons and rods. The silver segments were stoichiometrically converted to Ag 2 S by reaction with sulfide ions, generating Ag 2 S−Au−Ag 2 S heterojunction nanorods.

Shapeshifters: The shape and size of gold nanocrystals were controlled simultaneously through directed surface overgrowth from polyhedral and spherical seeds of different sizes. The resulting cubes, cuboctahedra, and octahedra (shown as SEM images for growth from spherical seeds of two sizes) exhibited characteristic optical properties in the visible range, which were analyzed by discrete dipole approximation calculations.

An asymmetric single hollow structure was generated from Ag-Au-Ag heterometal nanorods by a partial galvanic replacement reaction for the first time. The C(2)-symmetry breaking took place because of the random generation of a single pit on only one end of the silver domain at an early stage of the reaction. Careful control of the reaction kinetics could also yield a double-hollow structure on both ends of the silver domain. The resulting single- and double-hollow nanorods exhibited characteristi

Plasmonic nanostructures such as gold nanoparticles are very useful for monitoring chemical reactions because their optical properties are highly dependent upon the environment surrounding the particle surface. Here, we designed the catalytic structure composed of platinized cadmium sulfide with gold domains as a sensitive probe, and we monitored the photocatalytic decomposition of lactic acid to generate hydrogen gas in situ by single-particle dark-field spectroscopy. The plasmon band shift of

One-dimensional gold nanorods were synthesized from gold decahedrons in the presence of silver ions by a systematic overgrowth approach. Both the diameters and lengths of the nanorods were independently varied by using distinct-sized decahedrons and gold precursor concentrations. The key factors of anisotropic growth are three-dimensional decahedral seed structures and energetic differentiation of the distinct facets. A series of copper and silver underpotential deposition (UPD) experiments conf

Monitoring the dynamics of proteins in live cells on appropriate spatiotemporal scales may provide key information regarding long-standing questions in molecular and cellular regulatory mechanisms. However, tools capable of imaging the conformational changes over time have been elusive. Here, we present a single-molecule stroboscopic imaging probes by developing gyroscopic plasmonic nanoparticles, allowing for replication of protein-protein interactions and the conformational dynamics based on r

Formwandler: Form und Größe von Gold-Nanokristallen wurden durch gerichtetes Überwachsen polyedrischer und sphärischer Kristallkeime unterschiedlicher Größen simultan gesteuert. Die erhaltenen Würfel, Kuboktaeder und Oktaeder (siehe SEM-Bilder; Wachstum aus sphärischen Keimen zweierlei Größe) zeigen charakteristische optische Eigenschaften im sichtbaren Bereich, die durch DDA-Rechnungen (DDA=discrete dipole approximation) analysiert wurden.

Solar-driven reactive oxygen species (ROS) generation is an attractive disinfection technique for cell death and water purification. However, most photocatalysts require high stability in the water environment and the production of ROS with a sufficient amount and diffusion length to damage pathogens. Here, a ROS generation system was developed consisting of tapered crystalline silicon microwires coated with anatase titanium dioxide for a conformal junction. The system effectively absorbed >95%

Abstract Cells use gaseous molecules such as nitric oxide (NO) to transmit both intracellular and intercellular signals. In principle, the endogenous small molecules regulate physiological changes, but it is unclear how randomly diffusive molecules trigger and discriminate signaling programs. Herein, it is shown that gasotransmitters use time‐dependent dynamics to discriminate the endogenous and exogenous inputs. For a real‐time stimulation of cell signaling, we synthesized a photo‐cleavable met

Abstract Recent techniques for direct observation of single molecules or nanoparticles provide methodologies for imaging the activation sites of heterogeneous catalysts (spatially resolved) and observing intermediates that are not visible in the ensemble average (temporally resolved). Accordingly, the primary challenge for related experiments is obtaining sufficient spatial and temporal resolutions for microscopic observation of the chemical reaction of interest. This review discusses recent adv