Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

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


Reyes-Hernandez, D. , Mijares, G. , Nablo, B. , Briggman, K. and Gaitan, M. (2011), Trapping and Release of Citrate-Capped Gold Nanoparticles, Applied Surface Science, [online], (Accessed March 3, 2024)
Created August 1, 2011, Updated February 19, 2017