Logo image
Salt-mediated self-assembly of thioctic acid on gold nanoparticles
Journal article   Peer reviewed

Salt-mediated self-assembly of thioctic acid on gold nanoparticles

Anna A Volkert, Varuni Subramaniam, Michael R Ivanov, Amanda M Goodman and Amanda J Haes
ACS nano, Vol.5(6), pp.4570-4580
06/28/2011
DOI: 10.1021/nn200276a
PMCID: PMC3125453
PMID: 21524135

View Online

Abstract

Self-assembled monolayer (SAM) modification is a widely used method to improve the functionality and stability of bulk and nanoscale materials. For instance, the chemical compatibility and utility of solution-phase nanoparticles are often improved using covalently bound SAMs. Herein, solution-phase gold nanoparticles are modified with thioctic acid SAMs in the presence and absence of salt. Molecular packing density on the nanoparticle surfaces is estimated using X-ray photoelectron spectroscopy and increases by ∼20% when molecular self-assembly occurs in the presence versus the absence of salt. We hypothesize that as the ionic strength of the solution increases, pinhole and collapsed-site defects in the SAM are more easily accessible as the electrostatic interaction energy between adjacent molecules decreases, thereby facilitating the subsequent assembly of additional thioctic acid molecules. Significantly, increased SAM packing densities increase the stability of functionalized gold nanoparticles by a factor of 2 relative to nanoparticles functionalized in the absence of salt. These results are expected to improve the reproducible functionalization of solution-phase nanomaterials for various applications.
Algorithms Gold - chemistry Spectrometry, X-Ray Emission - methods Magnetic Resonance Spectroscopy - methods Models, Chemical Nanoparticles - chemistry Nanotechnology - methods Metal Nanoparticles - chemistry Ions Models, Statistical Static Electricity Salts - chemistry Solutions Thioctic Acid - chemistry Hydrogen-Ion Concentration

Details

Metrics

Logo image