Electrochemistry at gold nanoparticles deposited on dendrimers assemblies adsorbed onto gold and platinum surfaces

Abstract

Cyclic voltammetry and atomic force microscopy (AFM) were used to investigate the electrochemical communication between gold nanoparticles deposited onto adsorbed dendrimers of 4th generation poly(amido amine) (PAMAM) and gold or platinum electrode surfaces. Combination of these techniques evidenced that adsorption of dendrimers depends on both their chemical structures and the nature of the metallic surface. The adsorption process could be controlled as a function of either the dendrimer concentration or the time during which the electrodes were soaked in the dendrimer containing solution. Accordingly, mono- and multi-layer films of dendrimers could be obtained. The presence of dendrimer multilayer film did not prevent redox species such as ferrocene to reach the electrode surface presumably through pinholes in the dendrimers array. Interestingly, the dendrimer layer did not behave as an insulating film but was "electrochemically transparent" over the time ranges investigated. Thus, depositing gold nanoparticles over the dendrimer layers and constructing a self-assembled monolayer (SAM) consisting of 6-ferrocenyl hexanethiol onto the gold surfaces still allowed electrochemical communication with the ferrocene groups. This opens the future possibility of using dendrimers as anchors for gold nanoparticles so as to construct 2D-arrays of metal nanoparticles for electronic applications. (C) 2011 Elsevier B.V. All rights reserved.