Evaluating Aggregation of Gold Nanoparticles and Humic Substances Using Fluorescence Spectroscopy

The fate and transport of diagnostic gold nanoparticles in surface waters would significantly depend on their interactions with humic substances, which are ubiquitously found in natural aquatic systems. The current study employs UV−visible absorbance and fluorescence spectroscopy to investigate the...

Full description

Saved in:
Bibliographic Details
Published in:Environmental science & technology 2009-10, Vol.43 (19), p.7531-7535
Main Authors: Pallem, Vasanta L, Stretz, Holly A, Wells, Martha J. M
Format: Article
Language:English
Subjects:
Applied sciences
Chemical compounds
Ecotoxicology and Human Environmental Health
Exact sciences and technology
Fluorescence
Glucose
Gold
Gold - chemistry
Humic Substances - analysis
Metal Nanoparticles - chemistry
Nanoparticles
Pollution
Quenching
Spectrometry, Fluorescence
Spectrum analysis
Water Pollutants, Chemical - chemistry
Water Purification
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The fate and transport of diagnostic gold nanoparticles in surface waters would significantly depend on their interactions with humic substances, which are ubiquitously found in natural aquatic systems. The current study employs UV−visible absorbance and fluorescence spectroscopy to investigate the interactions of commercial humic acid (HA) with gold nanoparticles having a core size of 5 nm and coated with two different stabilizers, β-d-glucose and citrate. Humic substances (HS) are fluorescent in nature, providing a unique probe of nanometer-scale morphological changes for interactions between these natural polyelectrolytes and water-soluble gold nanoparticles. Quenching of fluorescence intensity was observed with β-d-glucose-coated gold nanoparticles, whereas an enhancement effect was noticed with the citrate-coated particles when mixed with HA having concentrations of 2 and 8 ppm (surface waters typically may contain ∼10 ppm HS). Examining the quenching and enhancement of fluorescence provides insight into the structural changes taking place at the coated gold nanoparticle−HA interface. The quenching behavior suggested ligand exchange due to nanometer-scale contact between the HA and β-d-glucose-coated gold nanoparticles, whereas the enhancement effect with citrate particles would indicate overcoating, leading to increased transfer distances for fluorescence resonance energy transfer.
ISSN:0013-936X
1520-5851
DOI:10.1021/es901201z