Nanotechnology

Alkanethiols and alkyl disulphides spontaneously form organised and densely packed monolayers on gold and silver surfaces through the attachment of the sulphur atom to the metal surface. This effect is known as self-assembly and the subsequent thiol layer is thus called a self-assembled monolayer (SAM). The formation of alkanethiol SAM is shown in the figure 1 below. A great deal of research has been carried out on SAMs since their discovery in 1983 and there are a number of potential applications in electronics and diagnostics.

Figure 1: self-assembly of alkanethiols on a gold surface

The self-assembly of alkanethiols can be used to pattern both metal and molecular surfaces. In microcontact printing, or soft lithography, a pattern of thiols can be placed on a metal surface using a molded elastomeric stamp. The stamp is inked with thiols and then printed onto the the metal surface, forming a self-assembled monolayer of thiols. The thiols can then act as a resist, protecting parts of the metal surface during a subsequent etch process to eventually leave a printed and etched pattern on the substrate. This technique can be used to print circuit patterns on thin films, leading to a range of applications from microelectronics to security bar-code tags.

The formation of SAMs on thin films can also be used in diagnostics and chemical sensors. The chemical and physical properties of the monolayer surface can be modified and controlled by varying the terminal functionality of the alkanethiol. Hence, alkanethiol SAMs linked with proteins or DNA can be used as chemical and biological sensors for disease detection, toxicology, forensics and environmental monitoring.

Robinson Brothers offers the following alkanethiols that all have application within nanotechnology: