Since the discovery of carbon nanotubes by lijima in 1991, various carbon nanotubes with either a single- or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size-dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat-panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.

Electrical and field-emission properties of chemically anchored single-walled carbon nanotube patterns Appl. Phys. Lett. 87, 013114 (2005); 10.1063/1.1968430Three-dimensional simulations of field emission through an oscillating barrier from a (10,0) carbon nanotube J.

The excellent optoelectronic, mechanical, and thermal properties of carbon nanotubes have made them very attractive for a wide range of potential applications. However, many applications require the growth of aligned carbon nanotubes with surface modification. We have developed a simple pyrolytic method for large-scale production of aligned carbon nanotube arrays perpendicular to the substrate. These aligned carbon nanotube arrays can be transferred onto various substrates of particular interest (e.g., polymer films for organic optoelectronic devices) in either a patterned or non-patterned fashion. The well-aligned structure further allows us to prepare aligned coaxial nanowires by electrochemically depositing a concentric layer of an appropriate conducting polymer onto the individual aligned carbon nanotubes. This approach is particularly attractive, as it allows surface characteristics of the aligned carbon nanotubes to be tuned to meet specific requirements for particular applications while their alignment structure can be largely retained. These aligned carbon nanotubes with tunable surface characteristics are of great significance to various practical applications. In this paper, we demonstrate the use of the conducting-polymer-coated aligned carbon nanotubes for electrochemical sensing applications.

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Hydrogels are three-dimensional, hydrophilic & polymeric networks capable of absorbing large amounts of water or biological fluids. Due to their high water content, porosity & soft consistency, they closely simulate natural living tissues, more so than any other class of synthetic biomaterials.Hydrogels can be formulated in a variety of physical forms, including slabs, micro-particles, Nanoparticles, coatings and films. As a result, hydrogels are commonly used in clinical practice & medicine for a wide range of applications, including Tissue engineering & Regenerative medicine, Diagnostics, Cellular immobilization, separation of biomolecules or cells, & barrier materials to regulate biological adhesions. Hydrogels are also relatively deformable & can conform to the shape of the surface to which they are applied. In the latter context, the bioadhesive properties of some hydrogels can be advantageous in immobilizing them at the site of application or in applying them on surfaces that aren't horizontal. They have started to create a niche in several fields of medicine like in specific site drug delivery, tissue reconstruction & tissue engineering and even as biosensors. In this review article an attempt has been made to explain the properties of hydrogels, their methods of preparation & its applications.