Metallic nanoshells on porphyrin-stabilized emulsions
View Patent ↗Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.
1. A nanoparticle comprising:
an emulsion droplet;
a plurality of lipoporphyrin molecules, wherein a hydrophobic substituent of the lipoporphyrin molecule is contained within a surface region of the emulsion droplet;
a metallic seed shell of diameter approximately equal to or greater than a diameter of the emulsion droplet and substantially surrounding the emulsion droplet;
a metallic outer shell atop the metallic seed shell, wherein the metallic seed shell and the metallic outer shell form a hollow nanoshell surrounding the emulsion droplet; and
a second metallic outer shell atop the metallic outer shell, wherein the metallic outer shell has a first metallic composition and the second metallic outer shell has a second metallic composition that is not identical to the first metallic composition.
2. The nanoparticle of claim 1 , wherein the emulsion droplet is substantially thermodynamically stable.
3. The nanoparticle of claim 1 , wherein the emulsion droplet comprises an organic liquid possessing a solubility in water suitable for forming an emulsion that is stable in water for a time required to form the metallic seed shell.
4. The nanoparticle of claim 1 , further comprising an inclusion particle that is solubilized in the emulsion droplet.
5. The nanoparticle of claim 4 , wherein the inclusion particle is selected from the group consisting essentially of Fe 3 O 4 , Fe 2 O 3 , TiO 2 , semiconductor quantum dots, metal particles, metal alloy particles, and solubilized versions thereof made soluble by surface modification with a material that facilitates solubilization.
6. The nanoparticle of claim 1 , wherein the metallic seed shell is Pt.
7. The nanoparticle of claim 1 , wherein the metallic outer shell is selected from the group consisting of Pt, Pd, Au, and Ag.
8. The nanoparticle of claim 1 , wherein the emulsion droplet comprises a material selected from the group consisting of benzene, chloroform, dichloromethane, and an organic oil capable of solubilizing the hydrophobic substituent of the lipoporphyrin molecule.
9. The nanoparticle of claim 1 , wherein the lipoporphyrin molecule comprises a hydrophilic head and a hydrophobic tail.
10. The nanoparticle of claim 9 , wherein the hydrophilic head comprises a hydrophilic segment selected from the group consisting of a hydroxyl group, an amide group, a carboxyl group, a pyridyl group, a sulfonate group, a phosphate group, and an amine group.
11. The nanoparticle of claim 9 , wherein the hydrophobic tail comprises a hydrophobic moiety selected from the group consisting of hydrocarbon units containing between 5 and 20 carbon atoms.
12. The nanoparticle of claim 1 , wherein the lipoporphyrin molecule is a metallo-lipoporphyrin.
13. The nanoparticle of claim 12 , wherein the metallo-lipoporphyrin comprises a photocatalytic metalloporphyrin unit.
14. The nanoparticle of claim 13 , wherein the photocatalytic metalloporphyrin unit is selected from the group consisting of a tin(IV) lipoporphyrin and tin(IV) meso-tetra(N-octadecyl-4-pyridyl)porphyrin chloride.
15. The nanoparticle of claim 1 , where the lipoporphyrin molecule is selected from the group consisting of Sn(IV) meso-tetra(N-octadecyl-4-pyridyl)porphyrin and salts thereof.
16. The nanoparticle of claim 5 , wherein a metal of the metal particles is selected from the group consisting of Au, Ag, Ni, and Co and a metal of the metal alloy particles is FePt.