Synthesis of unagglomerated metal nano-particles at membrane interfaces
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsMichael Markowitz, Gan Moog Chow, Alok Singh
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Abstract
The present invention relates to a powder of unagglomerated metallic particles. More particularly, the present invention relates to a powder of unagglomerated metallic particles having an average diameter of about 1-100 nm and the process for making the same. Additionally, the powder of unagglomerated metallic particles can be formed into a lyophilized form which upon reconstitution maintains the average diameter of between about 1-100 nm wherein the particles remain unagglomerated.
Claims16
A process for making a powder containing metallic particles, said process comprising the steps of:
- (1) forming a first dispersion of surfactant vesicles in the presence of catalytic first metal ions at a first concentration, said surfactant being
- lipid A or a mixture of lipid A and lipid B at a ratio of lipid A:lipid B, said lipid A having the structure (A):
- ##STR9## said lipid B having the structure (B):
- ##STR10## wherein R, R', R" and R'" are selected from the group consisting of saturated aliphatic, unsaturated aliphatic, haloaliphatic, aromatic, haloaromatic compounds and mixtures thereof, wherein R'" further comprises a positively charged group, said first concentration being not more than about a stoichiometrically sufficient concentration to bind to said lipid (A), said first dispersion having a pH;
- (2) forming a second dispersion by controlling said pH of said first dispersion to between about 5-7;
- (3) forming a third dispersion by mixing a metallization bath containing second metal ions with said second dispersion;
- and
- (4) forming a fourth dispersion by incubating said third dispersion at a temperature sufficient to reduce said second metal ions to metal particles having an average diameter between about 1-100 nm.
A process for creating unagglomerated metal nano-particles, the process comprising the steps of
- (a) forming a dispersion in an aqueous or polar solvent, the dispersion including unpolymerized lipid vesicles, the unpolymerized lipid vesicles each comprising at least one lipid bilayer, the lipid bilayer including a negatively charged lipid that has an anionic binding group, and the lipid vesicles having catalytic first metal ions bound thereto by ionic bonding,
- (b) combining the dispersion of step (a) with a metallization bath containing free second metal ions to form a mixture, and
- (c) incubating the mixture of step (b) at a temperature sufficient to reduce said free second metal ions and to form unagglomerated metal nano-particles having an average diameter between about 1-100 nm.
Dependencies are inferred from the claim text.