An electrical method to trap and release charged gold nanoparticles on and from the surface of alkanethiol self-assembled-monolayer (SAM) modified gold electrodes is presented. Gold nanoparticle (GNP) coated electrodes were formed by immersing amine-terminated SAM-modified gold electrodes into a solution of negatively-charged citrate-capped gold nanoparticles (GNPs). The electrostatic interactions kept the GNPs trapped on the electrode. The presence of the GNPs decreased the impedance of the SAM-modified electrode, and increased the electrochemical activity at at the electrode as shown through cyclic voltammetry. The application of a subsequent negative bias initiated a partial release of the gold nanoparticles. Impedance spectroscopy, cyclic voltammetry, UV-Vis spectrophotometry and AFM imaging were used to monitor the attraction and release of gold nanoparticles to and from the SAM-modified gold electrodes. This work describes a trapping and release method for citrate-capped gold nanoparticles that could find use in applications such as nanotoxicity studies and other microfluidic assays, and functionalization of gold nanoparticles.
Applied Surface Science
gold nanoparticles, electrostatic interactions, self-assembled monolayers