Surface enhanced spectroscopy-active composite nanoparticles
Metal nanoparticles associated with a spectroscopy-active (e.g., Raman-active) analyte and surrounded by an encapsulant are useful as sensitive optical tags detectable by surface-enhanced spectroscopy (e.g., surface-enhanced Raman spectroscopy).
1. A method of manufacturing a particle comprising:
a) associating a spectroscopy-active label with a surface-enhanced spectroscopy (SES)-active metal nanoparticle; and
b) coating said label-associated metal nanoparticle with an encapsulant, wherein said spectroscopy-active label has a measurable SES spectrum and wherein said encapsulant comprises a material selected from the group consisting of glass, polymers, metals, metal oxides, and metal sulfides.
2. The method of claim 1 , wherein said metal nanoparticle comprises a metal selected from the group consisting of Au, Ag, Cu, Na, Al, and Cr.
3. The method of claim 2 , wherein said metal nanoparticle comprises Au.
4. The method of claim 2 , wherein said metal nanoparticle comprises Ag.
5. The method of claim 1 , wherein said metal nanoparticle has a diameter less than about 200 nm.
6. The method of claim 5 , wherein said metal nanoparticle has a diameter between about 20 nm and about 200 nm.
7. The method of claim 6 , wherein said metal nanoparticle has a diameter between about 40 nm and about 100 nm.
8. The method of claim 1 , wherein said encapsulant has a thickness less than about 1 micron.
9. The method of claim 8 , wherein said encapsulant has a thickness between about 1 nm and about 40 nm.
10. The method of claim 9 , wherein said encapsulant has a thickness between about 5 nm and about 15 nm.
11. The method of claim 1 , wherein said metal nanoparticle comprises an alloy of metals selected from the group consisting of Au, Ag, Cu, Na, Al, and Cr.
12. The method of claim 1 , wherein said spectroscopy-active label forms a partial monolayer coating on said metal nanoparticle.
13. The method of claim 1 , wherein said spectroscopy-active label forms a monolayer coating on said metal nanoparticle.
14. The method of claim 1 , wherein said spectroscopy-active label forms a multilayer coating on said metal nanoparticle.
15. The method of claim 1 , wherein said encapsulant comprises a plurality of materials selected from the group consisting of glass, polymers, metals, metal oxides, and metal sulfides.
16. The method of claim 1 , wherein said encapsulant comprises glass (SiO x ).
17. The method of claim 1 , wherein said encapsulant comprises TiO x .
18. The method of claim 1 , wherein said measurable SES spectrum is a spectrum obtained by a method selected from the group consisting of surface-enhanced Raman spectroscopy, surface-enhanced resonance Raman spectroscopy, surface-enhanced hyper Raman spectroscopy, surface-enhanced resonance hyper Raman spectroscopy, and surface-enhanced infrared spectroscopy.
19. The method of claim 1 , wherein said surface-enhanced label is an aromatic analyte.
20. The method of claim 1 further comprising the step of functionalizing the surface of the encapsulated particles.
21. The method of claim 1 further comprising the step of separating the encapsulated particles from free particles of encapsulant.
22. The method of claim 21 , wherein said separation is performed by size-exclusion centrifugation.
23. The method of claim 21 further comprising the step of functionalizing the surface of the encapsulated particles.