Self Assembled Monolayer

Superoxide radical plays an important role in cell signaling. However, certain events can result in a large increase in superoxide concentration which has been linked to, among other conditions, inflammation, neurodegenerative diseases, and cancer. Consequently, in vivo detection of superoxide is of great interest. Previously, due to brittleness, instability, or size, superoxide sensors have been limited in their ability for

Gold nanoparticles and their arrays are some of the most studied nanomaterials, with promising applications in many fields such as electronics, optoelectronics, catalysis and biology. In order to protect bare gold nanoparticles from aggregation, to manipulate the optical, electronic and catalytic properties of the gold core, as well as to control interfacial properties, the gold nanoparticles are generally capped by an organic layer. Previous studies [C.D. Bain, G.M. Whitesides, J. Am. Chem. Soc. 110 (1988) 3665–3666] have revealed that many phenomena (e.g., wetting, friction and adhesion), are sensitive to the top few angstroms of a surface. The interfacial properties of a gold surface derivatized with a self-assembled monolayer will thus be dictated by the functionalities present on the outer side of the monolayer. The synthesis, functionalization and surface structure of monolayer-protected gold nanoparticles have been intensively studied in recent times [M.-C. Daniel, D. Astruc, Chem. Rev. 104 (2004) 293–346]. In addition, the aggregation and dispersion of colloidal nanoparticles is one of the key issues related to their potential applications. The forces that govern the colloid stability of nanoparticle dispersions, and how to control them, have yet to be fully investigated. Here special attention has been paid to control of colloid stability using external stimuli. In this feature article, the following five areas are reviewed: synthesis and applications of nanostructured particles; formation and structure of self-assembled monolayer protected gold nanoparticles; colloid stability—DLVO and non-DLVO forces; photochemistry, photochromism and pyrimidine; and manipulation of colloid stability with external stimuli.

In recent years, considerable progress has been made in the areas of molecular recognition and surface analysis. These fields meet in the field of sensor development, where the interaction between molecules and a suitably modified surface is of utmost importance. Vibrational spectroscopy is quite useful in these areas of research, as it may reveal the processes taking place at a molecular level. This thesis describes a number of applications of vibrational spectroscopy in the analysis of molecular recognition of molecules in solution, and in the characterisation of self-assembled interfaces. The study of molecular recognition of halide ions by specific hosts is reflected in the chapters 3, 4 and 5. In chapter 3, a new method is proposed for the determination of association constants applying infrared spectroscopy in combination with multivariate regression. This technique was developed to overcome the sensitivity problems arising when strongly associating complexes are investigated ...

The function of amperometric biosensors is related to electron-transfer processes between the active site of an (immobilized) enzyme and an electrode surface which is poised to an appropriate working potential. Problems and specific features of architectures for amperometric biosensors using different electron-transfer pathways such as mediated electron transfer, electron-hopping in redox polymers, electron transfer using mediator-modified enzymes and carbon-paste electrodes, direct electron transfer by means of self-assembled monolayers or via conducting-polymer chains are discussed.

Atomic force microscope images show that self-assembled monolayers of octadecyltrichlorosilane form on mica by nucleating isolated, self-similar domains. With increasing coverage, the fractal dimension of the growing domains evolves from 1.6 to 1.8. At higher coverage, continued growth is limited by adsorption from solution. Monte Carlo simulations that include, for the first time, adsorption as well as surface diffusion qualitatively

We demonstrate that interferometric lithography offers a fast, simple route to nanostructured self-assembled monolayers of alkylphosphonates on the native oxide of titanium. Exposure at 244 nm using a Lloyd's mirror interferometer caused the spatially periodic photocatalytic degradation of the adsorbates, yielding nanopatterns that extended over square centimetre areas. Exposed regions were re-functionalised by a second, contrasting alkylphosphonate, and the resulting patterns were used as templates for the assembly of molecular nanostructures; we demonstrate the fabrication of lines of polymer nanoparticles 46 nm wide. Nanopatterned monolayers were also employed as resists for etching of the metal film. Wires were formed with widths that could be varied between 46 and 126 nm simply by changing the exposure time. Square arrays of Ti dots as small as 35 nm (λ/7) were fabricated using two orthogonal exposures followed by wet etching.