Use of self-assembly monolayers

Callow ME, Callow JA, Ista LK, Coleman SE, Nolasco AC, Lopez GP (2000) Use of self-assembled monolayers of different wettabilities to study surface selection and primary adhesion processes of green algal (Enteromorpha) zoospores. Appl Environ Microbiol 66 3249-3254... 

Pacific Northwest National Laboratory (PNNL) is researching the use of self-assembled monolayers on mesoporous supports (SAMMS) technology for the removal of metals and radionuclides from liquid and gaseous hazardous wastes. SAMMS combines two technologies—mesoporous ceramic material and functionalized monolayers. The ceramic material has pores that increase its surface area. This ceramic material is coated with functionalized monolayers that form stable, covalent bonds with the contaminants. 

The use of self-assembled monolayer formation has been adapted to the deposition of conducting-polymer nanofilms by the chemical polymerization of aniline at an amino-silane surface that acts as the seed layer for polymerization, which led to a more ordered nanofibrous growth than would be seen using bulk chemical polymerization [39]. This was shown to be capable of detection of 0.5 ppm ammonia vapor, with a... 

The use of self-assembled monolayers (SAMs) for Investigating the binding properties of redox-active groups at a surface has been explored over the pact few years by a number of research groups Some... 

A broader range of sensor devices has been developed, where the sensor response is modulated by the presence of an imprinted polymer, or an imprinted surface. Perhaps the simplest way of preparing an imprinted surface is in the use of self-assembled monolayer (SAM) techniques. A cholesterol-specific SAM was prepared by Piletsky et al. [44], in which a gold electrode was treated with a solution of cholesterol and hexadecanethiol in methanol. After the SAM had been established, the template was removed, leaving cholesterol-shaped cavities in the imprinted surface. Amperometric measurements were then used to investigate the sensitivity of the electrode towards cholesterol. It was found that the unmodified electrode, and the imprinted electrode displayed the same peak current. However, exposure of the imprinted electrode to a solution of template caused a decrease in... 

The use of self-assembled monolayers (SAMs) for the analysis of species has not been explored sufficiently. MPc complexes substituted with thiols may be used to form SAMs. SAMs of CoOBTPc or FeOBTPc on gold were used to detect L-cysteine in acid media -The electrodes were very stable and reproducible. Detection limits for cysteine as low as 3.1 x 10 M were obtained. SAMs of FeOBTPc, FeOHETPc, CoOHETPc were used as electrocatalysts for the detection of the thiols L-cysteine (Figure 7.3a), homocysteine and penicillamine (Figure 7.3b) with detection limits in the 10 -10 M range. Lower oxidation potentials for these thiols were observed for the FePc derivatives when compared to CoPc derivatives, Table 7.2. 

As an example, consider the pervasive use of self-assembled monolayers (SAMs) for the surface modification of gold and silver substrates. A recent SERS/SERRS study of the Au film/SAM adsorbate interface demonstrates that thin films of Au(lll) on mica substrates, previously thought to be SERS-inactive, is SERS-active without any additional treatment. This discovery is quite... 

Israelachvili and coworkers [64,69], Tirrell and coworkers [61-63,70], and other researchers employed the SFA to measure molecular level adhesion and deformation of self-assembled monolayers and polymers. The pull-off force (FJ, and the contact radius (a versus P) are measured. The contact radius, the local radius of curvature, and the distance between the surfaces are measured using the optical interferometer in the SFA. The primary advantage of using the SFA is its ability to study the interfacial adhesion between thin films of relatively high... 

Johnson and coworkers [6], in their original paper on the JKR theory, reported the measurements of surface energies and interfacial adhesion of soft elastomeric materials. Israelachvili and coworkers [68,69], and Tirrell and coworkers [62, 63,70,88-90] used the SFA to measure the surface energies of self-assembled monolayers and polymer films, respectively. Chaudhury and coworkers [47-50] adapted the JKR technique to measure the surface energies and interfacial adhesion between self-assembled monolayers. More recently, Mangipudi and coworkers [55] modified the JKR technique to measure the surface energies of glassy polymers. All these measurements are reviewed in this section. 

The most commonly used amphiphiles to build L-B hlms for tribological applications are the straight chain hydrocarbon compounds with simple functional groups such as the fatty acids, including stearic acids, arachidic acids, and behenic acids [32], but other amphiphilic molecules, e.g., 2,4-heneicosanedione and 2-docosylamina-5-nitropyridine, are also applied in some cases. There are two major systems of self-assembled monolayers, namely the alkylsilance derivatives (e.g., OTS, octadecyltrichlorosilane) on hydroxylated surfaces and the alkanethiols on metal substrates, which have been investigated extensively to examine their properties as solid lubricants and protective surface films [31 ]. 

Monolayer films with the alkanethiol-capped ZnS Mn nanoparticles were fabricated on quartz substrates by the layer-by-layer method using a self-assembled monolayer of 1,6-hexanedithiol. 

Roberts C, Chen CS, Mrksich M, Martichonok V, Ingber DE, Whitesides GE (1998) Using mixed self-assembled monolayers presenting RGD and (EG)3OH groups to characterize long-term attachment of bovine capillary endothelial cells to surfaces. J Am Chem Soc 120 6548-6555... 

Another well-represented category was that of self-assembled monolayers (SAMS) and other supramolecular systems. The experiments on the SAMS included studies of the surface pKa of one system (110), the kinetics and thermodynamics of the self-assembly process (111), and the characterization of the SAM surface by study of solution contact angles (112). The experiments on supramolecular systems included studies on chemical equilibria in such systems (113, 114, 115), the kinetics of inclusion phenomena (116), and the use of solvatochromic probes in studying inclusion phenomena (117). 

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