Tubular structure of nanoparticles is highly attractive due to their structural attributes, such as the distinctive inner and outer surfaces, over conventional spherical nanoparticles. Inner voids can be used for capturing, concentrating, and releasing species ranging in size from large proteins to small molecules. Distinctive outer surfaces can be differentially functionalized with environment-friendly and/or probe molecules to a specific target. Magnetic particles have been extensively studied in the field of biomedical and biotechnological applications, including drug delivery, biosensors, chemical and biochemical separation and concentration of trace amounts of specific targets, and contrast enhancement in magnetic resonance imaging (MRI). Therefore, by combining the attractive tubular structure with magnetic property, the magnetic nanotube (MNT) can be an ideal candidate for the multifunctional nanomaterial toward biomedical applications, such as targeting drug delivery with MRI capability. Here, we successfully synthesized magnetic silica-iron oxide composite nanotubes and demonstrated the magnetic-field-assisted chemical and biochemical separations, immunobinding, and drug delivery.

A method is described for increasing luminescence in poly(p-phenylene vinylene) (PPV) light-emitting diodes. Cis linkages were engineered into the PPV chain. These linkages interrupt conjugation and interfere with the packing of the polymer chains, which results in the formation of amorphous PPV. Large-area electroluminescent devices were prepared from this polymer. Devices made of an aluminum electrode, PPV as the luminescent layer, and an electron-transporting layer have internal quantum efficiencies of 2 percent, a turn-on voltage of 20 volts, and can carry current densities of 2000 milliamperes per square centimeter. The current density is at least an order of magnitude higher than previously obtained.

and those measured on PDMS were 100.1 and 77.7. Surface energies of indium tin oxide (ITO) and Alq 3 and interfacial energy from the literature [14] which will bring revolutionary advances in the display technology, owing to attributes such as thin and flexible materials, fast switching times, and low-power consumption. However, current electrochromic technologies need to be improved in order to play moving images due to their slow color-switching rates.[1,2,5±11] Poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives are an ideal electrochromic material of conducting polymers for electronic paper due to their good color, mechanical stabilities, and facile fabrication.[5±11] Much work has been performed in order to improve contrast ratios and color switching rates by synthetic approaches.[5±11] It appears, however, that there are no examples of their use in electrochromic displays with moving-image speeds (24 frames/s; switching times of < 40 ms). This is due to the fact that the color-switching rate of PEODT is limited by the diffusion rate of counter-ions into the film during the redox process. The diffusion time, t, of ions required to reach a saturation concentration in a polymer film, that implies switching time, is proportional to the square of film thickness, x: t µ x 2 /D, where D is the diffusion coefficient of an ion in a polymer film. [12,13] Therefore, the simplest way to overcome the slow switching rates is to decrease the diffusion distance of ions, that is, to reduce film thickness. Based on the reported switching time of 2.2 s for a 300 nm thick PEDOT film, [5] we expect the switching time to be approximately 10 ms for a 20 nm thick film. However, the coloration of such a thin film is never sufficient for display applications. An array structure of PEDOT nanotubes provides an attractive solution to both of these limitations, slow switching rates and extent of coloration. Figure 1 explains that the wall thickness of PEDOT nanotubes can provide ions with short COMMUNICATIONS

"Template synthesized" silica nanotubes (SNTs) provide unique features such as end functionalization to control drug release, inner voids for loading biomolecules, and distinctive inner and outer surfaces that can be differentially functionalized for targeting and biocompatibility. Very limited information is available about their biological interactions. This work evaluates the influence of size and surface charge of SNTs on cellular toxicity and uptake. Results additionally indicate endocytosis to be one possible mechanism of internalization of SNTs.

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Shape-coded silica nanotubes (SNTs) were fabricated on the basis of template synthesis as a new dispersible microarray system. The template synthesis of shape-coded SNTs begins with the fabrication of a porous alumina film that has well-defined cylindrical pores with two or more different diameter segments by multistep anodization of an aluminum substrate. Then, SNTs were fabricated with a surface sol-gel method that can control the wall thickness of SNTs on the single-nanometer level. Attractively, the difference in optical reflectance between the segmented parts of individual silica nanotube makes it very convenient to identify each nanotube and enables these shape-coded SNTs to work as coding materials for biosensing.

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A suspension array for multiplexed immunoassays has been developed using shape-coded silica nanotubes (SNTs) as coding materials. Fabricated by multistep anodization template synthesis, each shape-coded SNT has several segments with different reflectance values depending on their diameters and wall thicknesses. Therefore, the code of each SNT can be "read-out" under a conventional optical microscope. The suspension array with shape-coded SNTs has shown high stability and dispersibility in aqueous buffer media and high detection sensitivity. The SNTs have not shown any visible degradation while submerged in aqueous solution for 7 months, the tubular structure and silanol groups on the inner and outer surfaces allow SNTs to disperse evenly in buffer solution, and the detection limit of an IgG protein is about 6 pM with 1.5 x 10(6) SNTs per mL. We have demonstrated the high selectivity of the SNTs suspension array for the detection of multianalytes in the multiplexed immunoassay experiments.