Directed self-assembly technique

Varghese B, Cheong FC, Sindhu S, Yu T, Lim CT, Valiyaveettil S, Sow CH (2006) Size selective assembly of colloidal particles on a template by directed self-assembly technique. Langmuir 22 8248-8252... 

Monolayers of alkyl chains on siUcon are a significant addition to the family of SAMs. An abiUty to directly connect organic materials to siUcon allows a direct coupling between organic materials and semiconductors. The fine control of supedattice stmctures provided by the self-assembly technique offers a route for building organic thin films with, for example, electrooptic properties on siUcon. 

A large number of potential applications for organized protein monolayers have recently motivated considerable research activity in this field (Boussaad et al. 1998, Kiselyova et al. 1999). Construction of specific interaction-directed, self-assembled protein films has been performed at the air-water interface. The Langmuir-Blodgett (LB) technique has been extensively used to order and immobilize natural proteins on solid surfaces (Tronin et... 

In this review, we describe the recent developments of chemically directed self-assembly of nanoparticle structures on surfaces. The first part focuses on the chemical interactions used to direct the assembly of nanoparticles on surfaces. The second part highlights a few major top-down patterning techniques employed in combination with chemical nanoparticle assembly in manufacturing two- or three-dimensional nanoparticle structures. The combination of top-down and bottom-up techniques is essential in the fabrication of nanoparticle structures of various kinds to accommodate the need for device applications. 

This chapter describes the self-assembly of non-native protein fibers known as amyloid fibrils and the development of these fibrils for potential applications in nanotechnology and biomedicine. It extends an earlier review by the author on a related topic (Gras, 2007). In Section 1, the self-assembly of polypeptides into amyloid fibrils and efforts to control assembly and any subsequent disassembly are discussed. In Section 2, this review focuses on the important role of surfaces and interfaces during and after polypeptide assembly. It examines how different surfaces can influence fibril assembly, how surfaces can be used to direct self-assembly in order to create highly ordered structures, and how different techniques can be used to create aligned and patterned materials on surfaces following self-assembly. 

A self-assembly DNA-conjugated polymer-based DNA detection method was previously mentioned. This study showed specific immobilization to a gold substrate with the self-assembly technique, not physical adsorption and great selectivity to fully matched DNA instead of nonspecific adsorption due to self-assembly DNA-conjugated polyallylamine and PAA coating [67,68]. However, a major problem was that we needed to prepare many kinds of DNA-conjugated polymer to analyze many kinds of target DNA due to direct modification of probe DNA to the polymer side chain. 

Based on ion-exchange and self-assembly techniques, in this paper we try to synthesize porous silica-montmorillonite heterostructured materials, starting with natural sodium montmorillonite which are ubiquitous so their cost effectiveness will continue to be lower than any synthetic competitive materials. The silica will be orderly assembled within gallery of layers, using the template-directing action. Through the catalytic alkylation reaction of catechol to produce polymerization inhibitor 4-tertbutylcatechol, the catalytic properties of porous silica-montmorillonite heterostructure were evaluated. 

Brinker and coworkers also prepared photoresponsive nanoporous silica particles using aerosol-assisted assembly, EISA, and surfactant-directed self-assembly (SDSA) techniques (Liu, 2004). The as-prepared photoresponsive nanocomposite particles were prepared so that the azobenzene ligands pointed toward the hydrophobic micellar interiors. After surfactant removal by solvent extraction, nanoporous particles with azobenzene ligands positioned on the pore surfaces were formed (Fig. 13.8). 

Enzyme sensors are another important application of metal nanoparticles in CMEs besides nonenzyme sensors. Many enzymes can keep their activity when anchored onto gold nanoparticles. A novel method for fabrication of a biosensor based on the combination of sol-gel and self-assembled techniques has been introduced very recently. For example, the gold nanoparticles and enzyme horseradish peroxidase (HRP) can be successfully immobilized on gold electrode by the help of sol-gel with thiol groups, and the direct electrochemistry of HRP has been achieved and the biosensor thus prepared exhibits fast response, good reproducibility, and long-term stability. 

Directing self-assembly (such as shear-induced orientation, templating techniques, confinement or selective annealing regimes) is not covered in this chapter, and the reader is directed elsewhere for a comprehensive review of this area. ... 

Other methods have been used to control grain size and orientation. Graphoepitaxy and chemical epitaxy make use of patterned substrates to direct self-assembly. Other externally applied fields, such as shear forces and electric fields, can also direct alignment. While primarily used in conjunction with thermal annealing, many have been demonstrated with solvent annealing as well. Several of these techniques have also shown the ability to cause perpendicular orientations of cylindrical and lamellar morphologies as well. 

---