Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Trapping and Release of Citrate-Capped Gold Nanoparticles



Darwin R. Reyes-Hernandez, Geraldine I. Mijares, Brian J. Nablo, Kimberly A. Briggman, Michael Gaitan


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
Created August 1, 2011, Updated February 19, 2017