Claims
- 1. 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.
- 2. The process of claim 1 further comprising the step of:
- (5) forming a fifth dispersion by separating said metal particles and said surfactant from said fourth dispersion.
- 3. The process of claim 2 further comprising the step of:
- (6) freeze drying said fifth dispersion to form said powder.
- 4. The process of claim 3 wherein said step (2) further comprises the step of:
- (7) dialyzing said first dispersion.
- 5. The process of claim 2 wherein said catalytic first metal ions are selected from the group consisting of Pd.sup.+2, Au.sup.+3, Co.sup.+2, Pt.sup.+2, Ni.sup.+2, Rh.sup.+2 and mixtures thereof.
- 6. 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.
- 7. The process of claim 6 wherein the lipid bilayer further includes an uncharged or zwitterionic lipid.
- 8. The process of claim 7 wherein the negatively charged lipid has the structure ##STR11## and wherein the uncharged or zwitterionic lipid is a zwitterionic lipid having the structure having the structure: ##STR12## wherein R, R', R" and R'" are selected from the group consisting of saturated aliphatic, unsaturated aliphatic, haloaliphatic, aromatic, haloaromatic groups and combinations thereof, wherein R'" further comprises a positively charged group.
- 9. The process of claim 8 wherein R, R', and R" are selected from the group consisting of:
- --(CH.sub.2).sub.y Z, ##STR13## --(CH.sub.2).sub.q '--CH.sub.3, --(CH.sub.2).sub.m '--C.tbd.C--C.tbd.C--(CH.sub.2).sub.n '--CH.sub.3, ##STR14## --(CH.sub.2).sub.a --(CH.dbd.CH).sub.b --(CH.sub.2).sub.c --(CH.dbd.CH).sub.d --(CH.sub.2).sub.e .dbd.CH.sub.3
- and combinations thereof, wherein Z is a member selected from the group consisting of a halogen, --H, --OH, --SH, --NH.sub.2, and --NHR"", wherein R"" is selected from the group consisting of aliphatic, substituted aliphatic, olefinic, substituted olefinic, aromatic and substituted aromatic groups, wherein x, y, y', q" and q' are integers between 0-20, wherein a, b, c, d, and e are integers between 0-20,
- wherein n' and n" are integers between 1-27, wherein m' is an integer between about 1-28 and wherein 3.ltoreq.(n'+m').ltoreq.29 and
- wherein R'" is represented by the structure
- --(CH.sub.2).sub.f --N.sup.+ (CH.sub.3).sub.3
- wherein f is an integer between 1-10.
- 10. The process of claim 6 wherein the catalytic first metal ion is selected from the group consisting of Pd.sup.+2, Au.sup.+3, Co.sup.+2, Pt.sup.+2, Ni.sup.+2, Rh.sup.+2 and combinations thereof.
- 11. The process of claim 6 wherein the second metal ions are ions of a metal selected from the group consisting of Group IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIII metals and combinations thereof.
- 12. The process of claim 6 wherein the second metal ions are ions of metals selected from the group consisting of Au, Ag, Pd, Cu, Rh, Ru, Ni, Co, Pt, Fe, W, Cr, Mn, Ti and combinations thereof.
- 13. The process of claim 6 wherein the dispersion of step (a) is formed by the steps of
- (i) combining a negatively charged lipid with a catalytic first metal ion in a polar or aqueous solvent at a temperature above room temperature to form a mixture,
- (ii) allowing the mixture of step (i) to cool to room temperature, and
- (iii) controlling the pH of the mixture of step (ii) to fall within the range of from about 5 to about 7,
- whereby, in steps (ii) and (iii), the negatively charged lipid self-assembles into lipid vesicles, each vesicle comprising at least one lipid bilayer, and whereby the catalytic first metal ion binds to the lipid vesicles by ionic bonding.
- 14. The process of claim 13 wherein, in step (iii) of the formation of the dispersion of step (a), the pH is controlled by dialysis with water.
- 15. The process of claim 6 including the further step (d) of separating the unagglomerated metal nano-particles and the lipid vesicles from the mixture of step (c).
- 16. The process of claim 15 including the further step (e) of lyophilizing the unagglomerated metal nano-particles and lipid vesicles of step (d).
Parent Case Info
This is a division of application Ser. No. 08/603,296, filed Feb. 20, 1996, now U.S. Pat. No. 5,876,480 entitled SYNTHESIS OF UNAGGLOMERATED METAL NANOPARTICLES AT MEMBRANE INTERFACES.
US Referenced Citations (9)
Non-Patent Literature Citations (2)
Entry |
Michael Markowitz, Gan-Moog Chow & Alok Singh, "Polymerized Phospholipid brane Mediated Synthesis of Metal Nanoparticles", Langmuir, Nov. 1994, pp. 4095-4102. |
A. Singh, M. Markowitz, and G.M. Chow, "Materials Fabrication via Polymerizable Self-organized Membranes: an Overview, NanoStructured Materials", vol. 5, No. 2, pp. 141-153 (1995). |
Divisions (1)
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Number |
Date |
Country |
Parent |
603296 |
Feb 1996 |
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