Linker molecular monolayer

Most of the linker molecular monolayers are stable over broad potential ranges, limited by reductive and oxidative desorption and cleavage of the Au-S bond. The adsorption process can be followed in real time through several intermediate phases, such as reported for cysteamine [38] (and 1-propanethiol [155]). The in situ STM images shown in Figure 2.6 thus offer an overall impression of the microenvironment for immobilized redox proteins in voltammetric action. ... 

Most of the linker molecular monolayers are stable over broad potential ranges, limited by reductive and oxidative desorption and cleavage of the... 

Electrochemically controlled SAMs of the alkanethiol class characterized to high voltammetric resolution and to molecular and sub-molecular structural in situ STM resolution have been reviewed recently [60, 151]. We note here first some issues of importance to functionalized alkanethiols as linker molecules for gentle immobilization of fully functional redox metalloprotein monolayers on singlecrystal Au(lll) electrode surfaces. We discuss next specifically the functionalized alkanethiols cysteine (Cys) and homocysteine (Hey). These two molecules represent a core protein building block and a core metabolite, respectively. The former has been used to display unique sub-molecular in situ STM resolution [152]. The latter shows a unique dual surface dynamics pattern that could be followed both by single-molecule in situ STM and by high-resolution capacitive voltammetry. 

Figure 8-10. Overview of small linker molecules recently characterized to molecular resolution by in situ STM on Au(lll)-electrode surfaces in aqueous buffer under potential control. A Bare reconstructed Au(l 11 )-surface. B (2 3 xV3)R30°-4 butanethiol monolayer (hydrophobic). C (2 3 x 6)R30°-6 monolayer of mercaptopropionic acid (negatively charged).D (V3 x 4)R30°-2 monolayer of cysteamine (positively charged). E (3 3 x 6)R30°-6 monolayer of cysteine/cystine (zwitterionic). ...

There are different methods to prevent the nonspecific adsorption of proteins onto surfaces, for example by adding surfactants or bovine serum albumin (BSA) to protein solutions, or by the widely applied method using self-assembled monolayers (SAMs) that are protein-resistant , such as SAMs with oUgo(ethylene glycol), l.e. OEG chains. These SAMs prevent nonspecific interactions due to their loose packing and the weU-hydrated nature. Such molecularly imprinted P-CD polymers, i.e. the P-CD molecular printboards were used as a platform for the immobilization of proteins through small multivalent orthogonal linker molecules. 

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