Feb 29, 2008
Reversible, reagentless solubility changes in phosphatidylcholine-stabilized gold nanoparticles
This paper describes an approach for preparing gold nanoparticles using an environmentally benign method. This new synthetic route utilizes non-toxic components from soybeans. By using phosphatidylcholine (lecithin) extracted from soy as a ligand, nanoparticles with unique solubility properties were discovered. These lipid-stabilized gold nanoparticles can be synthesized in either aqueous or organic solvents and then can be resuspended in a different solvent without using additional reagents or chemical modification. This reversible solubility change results from the amphiphilic properties of the phosphatidylcholine ligand and can be repeated multiple times without altering the size, shape or optical properties of the nanoparticles.
For practical use, the solubility conversion method allows for modification of a nanoparticle in one solvent prior to use in a second solvent. This will open new avenues to nanoparticle assembly, modification and biofunctionalization. These materials will be useful in several applications including the design of biosensors and in studying membrane–protein interactions. Furthermore, this route has already been shown to be an effective method of preparing water-soluble nanoparticles of narrow-dispersity.
There is an emerging need for synthetic routes that produce non-toxic nanomaterials especially for nanoparticles being considered for use in medical applications. By synthesizing nanoparticles using benign building blocks, the likelihood of toxicity caused by impurities or decomposition products can be reduced. Lipids obtained from inexpensive renewable feedstock are ideal benign building blocks for the synthesis of greener nanomaterials. The toxicity of these and other nanoparticles are being assessed using screens available through the Safer Nanomaterials and Nanomanufacturing Initiative. By learning what properties influence toxicity it will be possible to further improve the syntheses.
About the author
Postdoctoral researcher Marilyn M Mackiewicz and graduate student, Benjamin R Ayres work with the Safer Nanomaterials and Nanomanufacturing Initiative to design new routes for synthesizing nanomaterials with minimal environmental impacts. They work at Portland State University in the lab of Professor Scott M Reed, a member of the Department of Chemistry and the Oregon Nanoscience and Microtechnologies Institute.