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Surfactant layering on mixed monolayer-protected gold clusters
Catherine M Goodman1, Benjamin L Frankamp, Beth M Cooper
1Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA.
Colloids and Surfaces. B, Biointerfaces
|November 24, 2004
Summary
Positively-charged gold clusters become soluble in organic solvents at low sodium dodecyl sulfate (SDS) concentrations. Higher SDS levels cause these clusters to aggregate into water-soluble assemblies, revealing their morphology and properties.
Area of Science:
- Materials Science
- Colloid Chemistry
- Nanotechnology
Background:
- Monolayer Protected Gold Clusters (MPCs) are nanomaterials with tunable properties.
- Surfactants like Sodium Dodecyl Sulfate (SDS) are crucial for controlling nanoparticle behavior in solution.
- Understanding nanoparticle solubility and aggregation is key for their application.
Purpose of the Study:
- To investigate the effect of Sodium Dodecyl Sulfate (SDS) concentration on the solubility and aggregation of positively-charged Monolayer Protected Gold Clusters (MPCs).
- To characterize the morphology and properties of the resulting nanoparticle assemblies.
Main Methods:
- Mixing positively-charged Monolayer Protected Gold Clusters (MPCs) with varying concentrations of Sodium Dodecyl Sulfate (SDS).
- Solubility tests in organic solvents and water.
- Characterization using Sodium Cyanide (NaCN) decomposition, Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS).
Main Results:
- At low SDS concentrations, MPCs transitioned from water-soluble to organic-soluble while maintaining discrete particle form.
- At higher SDS concentrations, MPCs aggregated into water-soluble assemblies.
- Characterization techniques confirmed the morphology and properties of these encapsulated assemblies.
Conclusions:
- Sodium Dodecyl Sulfate (SDS) concentration is a critical factor in controlling the solubility and aggregation state of positively-charged Monolayer Protected Gold Clusters (MPCs).
- The study demonstrates a method for tuning nanoparticle behavior for potential applications in different solvent systems.