No abstract

Delivery of biomolecules with use of nanostructures has been previously reported. However, both efficient and high-throughput intracellular delivery has proved difficult to achieve. Here, we report a novel material and device for the delivery of biomacromolecules into live cells. We attribute the successful results to the unique features of the system, which include high-aspect-ratio, uniform nanoneedles laid across a 2D array, combined with an oscillatory feature, which together allow rapid, forcible and efficient insertion and protein release into thousands of cells simultaneously.

Many emerging applications in microscale engineering rely on the fabrication of 3D architectures in inorganic materials. Small-scale additive manufacturing (AM) aspires to provide flexible and facile access to these geometries. Yet, the synthesis of device-grade inorganic materials is still a key challenge toward the implementation of AM in microfabrication. Here, a comprehensive overview of the microstructural and mechanical properties of metals fabricated by most state-of-the-art AM methods that offer a spatial resolution ≤10 μm is presented. Standardized sets of samples are studied by cross-sectional electron microscopy, nanoindentation, and microcompression. It is shown that current microscale AM techniques synthesize metals with a wide range of microstructures and elastic and plastic properties, including materials of dense and crystalline microstructure with excellent mechanical properties that compare well to those of thin-film nanocrystalline materials. The large variation in materials' performance can be related to the individual microstructure, which in turn is coupled to the various physico-chemical principles exploited by the different printing methods. The study provides practical guidelines for users of small-scale additive methods and establishes a baseline for the future optimization of the properties of printed metallic objects-a significant step toward the potential establishment of AM techniques in microfabrication.

Performance of nonresonant tunnel conduction through a self-assembled monolayer of conjugated molecules fabricated on gold (111) was determined by virtue of nanometer-scale electrical probe measurement using a conductive atomic force microscope. Electrical measurements with nanometer spatial resolution enabled mapping of tunnel current as well as efficiency of tunnel conduction through molecular wire by analyzing length dependence on current. A series of conjugated molecules with different numbers of oligothiophene rings proved to possess a high tunnel-conduction efficiency.

We describe a novel fabrication method of three-dimensional (3D) microstructures using local electrophoresis deposition together with laser trapping. A liquid cell consisting of two-faced conductive substrates was filled with a colloidal solution of Au nanoparticles. The nanoparticles were trapped by a laser spot and positioned on the bottom substrate, then deposited onto the surface by the application of electrical voltage between the two substrates. By moving the liquid cell downward while maintaining the deposition, 3D microstructures were successfully fabricated. The smallest diameter of the fabricated pillar was 500 nm, almost the same as that of the Airy disc. The Young's modulus of the fabricated structure was 1.5 GPa.

We describe a novel technique of local electrophoretic deposition of colloidal particles using a scanning probe microscope with a nanopipette probe filled with a colloidal solution. The colloidal solution including nanometre-scale particles was put into the nanopipette probe. A thin metal wire was inserted into the nanopipette probe as an electrode for the electrophoretic deposition. With the probe edge nearly in contact with the conductive surface and with an electric potential applied between the electrode and the surface, the colloidal particles migrated toward the edge of the probe, causing them to be deposited on the surface. It was possible for nanometre-scale Au colloidal particles in an aqueous solution to be deposited on Si surfaces. The size of the Au dots could be modified by adjusting the deposition time and voltage. Dot array and line patterns were successfully plotted on the surface. This technique of local deposition should provide the possibility for fabricating nanostructures such as nanomachines and nanoelectronics.

No abstract

The elasticity of the periodic bundle structure formed by the interaction between the tip of an atomic force microscope and a polycarbonate surface was studied. The local elasticity of the bundle was observed using ultrasonic force microscopy, which combines the sensitivity to an elastic structure of acoustic microscopy with atomic force microscopy. The mean height of the bundle increases with increase in the number of scan-scratching cycles. The process of decreasing elasticity of a growing bundle of polycarbonate was observed clearly. Furthermore, the elasticity contrast inside the bundle structure was observed by adjusting the amplitude of ultrasonic vibration of sample height in ultrasonic force microscopy.