Rapid and efficient sonochemical formation of gold nanoparticles under ambient conditions using functional alkoxysilane.

Gold nanoparticles (NPs) are rapidly and efficiently formed under ambient conditions with a novel and highly-efficient sonochemical promoter. Despite of the presence of free oxygen, 3-glycidoxypropyltrimethoxysilane (GPTMS) showed remarkable efficiency in promoting the reduction rate of Au (III) than that of conventional promoters (primary alcohols). This is likely attributed to the formation of a variety of radical scavengers, which are alcoholic products from sonochemical hydrolysis of the epoxide group and methoxysilane moieties of GPTMS under weakly acidic conditions.

Fabrication and performance of a microfluidic traveling-wave electrophoresis system.

A microfluidic traveling-wave electrophoresis (TWE) system is reported that uses a locally defined traveling electric field wave within a microfluidic channel to achieve band transport and separation. Low voltages, over a range of -0.5 to +0.

Fabrication of 3D metal dot arrays by geometrically structured dynamic shadowing lithography.

Sphere lithography (SL), sometimes erroneously generalized as nanosphere lithography (NSL), stands out as a versatile technique capable of producing 2D periodic micro- and nanostructures with general materials applicability, flexible size and shape control, high throughput, and elegance of simplicity. Many of the fundamental aspects of the features produced by SL have been investigated in a systematic manner, including the optical, magnetic, electronic, and catalytic behaviors with emphasis toward applications in biosensing, ultrasensitive spectroscopy, and nanodevice fabrication. Previous work has primarily focused on two-dimensional patterning, however, with little attention paid to vertical growth of the SL features.

Selective attachment of F-actin with controlled length for developing an intelligent nanodevice.

Development of the nanodevice that myosin-coated beads "walk" on actin filaments (F-actin) tracks for in vitro nanotransportation was hindered due to the difficulty of assembling large-area well-orientated F-actin tracks on the surface. In this work, we present a selective attachment of F-actin with controlled length on a patterned surface by employing biotinylated capped protein gelsolin as intermediate anchoring bridge. A patterned streptavidin layer was formed via coupling with a biotin layer that photo-actively attached to an amine-functionalized glass surface.

Motion analysis of self-propelled Pt-silica particles in hydrogen peroxide solutions.

Silica microspheres that are half-coated with platinum metal undergo self-propulsion in solutions of H(2)O(2), with the average speed increasing with increasing H(2)O(2) concentration. Microscopic observation of the particle motion, with segmentation of the image data, demonstrates that the particles move, on average, with the platinum-coated region oriented opposite to the direction of motion. Velocity autocorrelation and motion direction analyses show that the direction of motion is highly correlated with the particle orientation.

Traveling-wave electrophoresis for microfluidic separations.

Models and microfluidic experiments are presented of an electrophoretic separation technique in which charged particles whose mobilities exceed a tunable threshold are trapped between the crests of a longitudinal electric wave traveling through a stationary viscous fluid. The wave is created by applying periodic potentials to electrode arrays above and below a microchannel. Predicted average velocities agree with experiments and feature chaotic attractors for intermediate mobilities.

Magnetically actuated nanorod arrays as biomimetic cilia.

We present a procedure for producing high-aspect-ratio cantilevered micro- and nanorod arrays of a PDMS-ferrofluid composite material. The rods have been produced with diameters ranging from 200 nm to 1 mum and aspect ratios as high as 125. We demonstrate actuation of these superparamagnetic rod arrays with an externally applied magnetic field from a permanent magnet and compare this actuation with a theoretical energy-minimization model.

Ligament cells stretch-adapted on a microgrooved substrate increase intercellular communication in response to a mechanical stimulus.

An in vitro model was used to investigate the effect of mechanical stimuli on adaptation to load and calcium signaling in aligned medial collateral ligament cells (MCL). This model used a patterned silicone membrane to align the cells parallel with the direction of the microgrooves. Alignment created an architecture that simulated a degree of cell orientation in native ligament tissue.

The genesis of molecular electronics.

Molecular electronics is, relatively speaking, a young field. Even so, there have been many significant advances and a much greater understanding of the types of materials that will be useful in molecular electronics, and their properties. The purpose of this review is to provide a broad basis for understanding the areas where new advances might arise, and to provide introduction to the subdisciplines of molecular electronics.