Modifying layer containing gold clusters on a monolayer of organothiol transfers charge to the redox couple in the solution more efficiently than without nanoclusters [Scheme 1].

The clusters bound to the electrode by means of 1,9-nonanedithiol (NDT) are more uniformly distributed on the monolayer and their efficiency in transferring electrons between the electrode and [Fe(CN)₆]^4-/3- couple in the solution is better than when they are bound by means of weak van der Waals interactions only (as in case of 1-decanethiol (DT)). With increasing adsorption time in the solution of clusters, the capacitance of the cluster decorated electrode significantly increases compared to its constant value after prolonged immersion in pure toluene. This difference is explained assuming that gold clusters adsorb on the monolayer modified surface and act as an array of capacitors increasing in number.

Scheme 1. Structure of electrode modified with gold nanoparticles supported on gold electrode by means of organothiol monolayer.

The 4-hydroxythiophenol monolayer modified gold clusters attached to electrodes by means of dithiol molecules transfer charge to the DOPA (3,4-dihydroxyphenylalanine) and ascorbic acid (AA) molecule in the solution more efficiently than when the same 1,9-nonanedithiol or 4-hydroxythiophenol are assembled in form of a monolayer directly on the gold substrate. Probably, the clusters attached to the monolayer on the electrode surface play here the role of electron accepting units, and charge during the potential scan. This would allow them to act as individual microelectrodes in the process of AA and DOPA oxidation.