Porous precious metals with pore size distributions centered below 5 nm are useful for applications in electrocatalysis, sensing, and others, where the combination of high surface area and electric contact to all surface sites is advantageous. Such materials possess the virtues of nanoparticles with their good surface-area-to-volume ratio and few of their downsides, for example, there are no supports to corrode or de-adhere from and particle sintering would not lead to a reduction in surface area. A few methods have been developed to make porous precious metals with pore sizes below 5 nm. One method is templated growth, plating into the interstices of a porous parent phase that is later removed.[1] A different methoddealloying -is receiving increased attention recently because of its ease in processing.[2] One starts with a monolithic alloy in any form factor, such as bulk or thin film, and selectively electrochemically dissolves the less-noble component of the alloy. Here, we demonstrate that small fractions of Pt added to precursor Ag/Au alloys result in a new ultraporous metal upon dealloying, possessing a pore size peaked at less than 4 nm, a self-assembled core/shell structure, and remarkable stability against coarsening. The material called nanoporous gold (NPG or np-Au) is made by dealloying silver from Au/Ag alloys with compositions of Au in the 20 -40 at % range; in this way, one makes a beautiful nanoporous form of nearly pure gold with pore size in the 10-20 nm range. NPG is being used by a number of groups in a variety of important ''nano''-related applications. The thermodynamics of surface stress at the nanoscale leads to physical actuation of NPG under electrochemical potential control; [3] it is a good substrate for surface enhanced Raman spectroscopy (SERS); [4] and NPG is a good substrate on which to coat catalytically useful materials such as Pt or thiol-based self-assembled monolayers [5] (it is also unusually catalytic itself [6][7][8][9] ). Unfortunately, NPG is prone to coarsening, particularly in acidic environments, reducing its long-term functionality.[10]

We report on the first use of carbon-nanotube based films to produce crystals of proteins. The crystals nucleate on the surface of the film. The difficulty of crystallising proteins is a major bottleneck in the determination of the structure and function of biological molecules. The crystallisation of two model proteins and two medically relevant proteins was studied. Quantitative data on the crystallisation times of the model protein lysozyme are also presented. Two types of the nanotube film, one made with the surfactant Triton X-100 (TX-100) and one with gelatin, were tested. Both induce nucleation of the crystal phase at supersaturations at which the protein solution would otherwise remain clear, however the gelatin-based film induced nucleation down to much lower supersaturations for the two model proteins with which it was used. It appears that the interactions of gelatin with the protein molecules are particularly favourable to nucleation. Crystals of the C1 domain of the human cardiac myosin-binding protein-C that diffracted to a resolution of 1.6Å, were obtained on the TX-100 film. This is far superior to the best crystals obtained using standard techniques, which only diffracted to 3.0 Å. Thus, both our nanotube-based films are very promising candidates for future work on crystallising difficult-tocrystallise target proteins.3

Silver (Ag) nanoparticles are of great interest for many applications. However, their fabrications have been limited by the synthesis methods in which size, shape, and aggregation are still difficult to control. Here, we reported on using direct current (DC) magnetron sputtering for growing Ag nanoparticles on unheated substrates. Effects of sputtering condition on grain size of Ag nanoparticle were discussed. At constant sputtering current and deposition time, the average sizes of Ag nanoparticles were 5.9 ± 1.8, 5.4 ± 1.3, and 3.8 ± 0.7 nm for the target-substrate distances of 10, 15, and 20 cm, respectively. The morphology evolution from nanoparticles to wormlike networks was also reported. High-resolution transmission electron microscopy image represented clear lattice fringes of Ag nanoparticles with a d-spacing of 0.203 nm, corresponding to the (200) plane. The technique could be applied for growth of nanoparticles that were previously difficult to control over size and size uniformity.

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Al2O3nanoparticles were synthesized using laser ablation of an aluminum (Al) target in deionized water. Nd:YAG laser, emitted the light at a wavelength of 1064 nm, was used as a light source. The laser ablation was carried out at different energies of 1, 3, and 5 J. The structure of ablated Al particles suspended in deionized water was investigated using X-ray diffraction (XRD). The XRD patterns revealed that the ablated Al particles transformed intoγ-Al2O3. The morphology of nanoparticles was investigated by field emission scanning electron microscopy (FE-SEM). The FE-SEM images showed that most of the nanoparticles obtained from all the ablated laser energies have spherical shape with a particle size of less than 100 nm. Furthermore, it was observed that the particle size increased with increasing the laser energy. The absorption spectra of Al2O3nanoparticles suspended in deionized water were recorded at room temperature using UV-visible spectroscopy. The absorption spectra show a strong peak at 210 nmarising from the presence of Al2O3nanoparticles. The results on absorption spectra are in good agreement with those investigated by XRD which confirmed the formation of Al2O3nanoparticles during the laser ablation of Al target in deionized water.

Here we culture Chinese Hamster Ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes, no lithography is required to make inexpensive largescale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over lengthscales comparable to the cell size and show that the cells follow this pattern.3

Natural materials, such as bone and spider silk, possess remarkable properties as a result of sophisticated nanoscale structuring. They have inspired the design of synthetic materials whose structure at the nanoscale is carefully engineered or where nanoparticles, such as rods or wires, are self-assembled. Although much work has been done in recent years to create ordered structures using diblock copolymers and template-assisted assembly, no reports describe highly ordered, three-dimensional nanotube arrays within a polymeric material. There are only reports of two-dimensional network structures and structures on micrometer-size scales. Here, we describe an approach that uses plasticized colloidal particles as a template for the self-assembly of carbon nanotubes (CNTs) into ordered, three-dimensional networks. The nanocomposites can be strained by over 200% and still retain high conductivity when relaxed. The method is potentially general and so may find applications in areas such as sensing, photonics, and functional composites.

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