Gate sites in surface monolayers

Gate sites may be formed in self-assembled monolayers when the layers are prepared on surfaces in the presence of a template which is subsequently extracted (Fig. 18.7). The principle was first described by Sagiv using visible absorption spectroscopy to determine the uptake of cyanine dyes [106]. Yamamura and co-workers 

Biomimetic electrochemical sensors based on molecular imprinting 

Very recently Lahav et al. [116] used a photochemically cleavable template to introduce gate sites into an alkanethiol self-assembled monolayer on a gold electrode. The electrode showed an enhanced amperometric response to the electroactive template, compared with an electrode with a monolayer without gate sites. 

Gate sites in silane monolayers on tin (IV) oxide electrodes have also been studied for resistometric gas-phase sensing [117]. 

Common to many of these studies is that selectivity, where it has been examined at all, has only been reported between the template and species of quite different charge or polarity. It is difficult in such cases to attribute selectivity to the geometry of the gate sites rather than changes in the bulk properties of the electrode surface. Gate sites in self-assembled monolayers provide a simple method for the modification of sensor surfaces. However, the degree of selectivity obtainable in this way. 

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